• HVYSNOW: Probabilistic Heavy Snow And Icing Discussion

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, January 23, 2026 20:57:19
    FOUS11 KWBC 232057
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    357 PM EST Fri Jan 23 2026

    Valid 00Z Sat Jan 24 2026 - 00Z Tue Jan 27 2026


    ...Major winter storm to bring the potential for crippling icing,=20 significant sleet, and heavy snow from the Southern Plains through=20
    the Southeast and up the Atlantic Coast into New England...

    Meteorological Overview...

    A massive winter storm, set to produce a swath of heavy snow and=20
    dangerous ice accumulations, has begun today as tropical East=20
    Pacific moisture streams out ahead of the 500mb closed low near the
    Baja Peninsula. This moisture plume is clashing with the coldest=20
    air-mass of the season, entrenching itself over the Nation's=20
    Heartland. The moisture transport is exceptional with an
    integrated vapor transport (IVT) above the 97.5 climatological=20
    percentile per ECMWF SATs. The rich moisture from the south will=20
    accompany strong 850-700mb WAA that results in classic over-runing=20
    along a developing area of 850-700mb FGEN atop the Southern Plains.
    Meanwhile, the upper trough in the Southwest and an emerging=20
    upper- level shortwave trough over the Dakotas will strengthen a=20
    250mb jet streak over the east-central U.S., placing its thermally-
    direct right-entrance region over the Southern Plains. This=20
    synoptic- scale setup helps to enhance the mesoscale below,=20
    fostering heavy bands of snow and even elevated instability above=20
    the low-level sub-freezing layer over north TX on east into the=20
    Mid-South tonight and into Saturday.

    By Saturday, as the upper low near Baja approaches Texas, its=20
    associated jet streak over Mexico will co-locate its divergent=20
    left-exit region over the Mid-South and maximize upper-level ascent
    over the region. The IVT in advance of the upper trough over=20
    Mexico is both expansive and strong with >90th climatological=20
    percentile IVT values originating south of Mexico and extending all
    the way to the Southern Appalachians by Saturday afternoon. The=20
    remarkable extent of the IVT and the slow progression of the Mexico
    trough is why parts of the South and Mid-Atlantic are likely to=20
    see snow, sleet, and freezing rain for over 24 hours and in some=20
    cases approaching 48 hours. As arctic high pressure slides east, a=20
    cold-air damming (CAD) signature will become well pronounced along=20
    and east of the Appalachians as anomalous Pacific and Gulf moisture
    arrives, leading to precipitation falling into the frigid air-mass
    and supporting heavy snow, sleet, and freezing rain totals from=20
    the southern Appalachians to the Mid-Atlantic.=20

    Saturday night and into Sunday is where most changes in the
    forecast have unfolded of late. It remains unclear just how strong
    the emerging area of low pressure near the Gulf Coast will be and=20
    how far north it gets. It is noteworthy that guidance is in good=20
    agreement on 700mb Q-vector convergence over northern AL and the=20
    southern Appalachians, but the GFS is a little farther south in=20
    positioning while the ECMWF is a littler farther north and=20
    stronger, resulting in the northern shifts over the last couple=20
    days. What they do both agree on is by Sunday, a very pronounced=20
    area of strong 700mb Q-vector convergence will unfold along the=20
    Mid-Atlantic coast, prompting the development of a coastal low=20
    along a strengthening coastal front. With the benefit of the 250mb
    jet streak's divergent right-entrance region aloft and the=20
    strengthening IVT (ECMWF SATs show >99.5 climatological percentile=20
    values over the Southeast Sunday morning), an expansive=20
    precipitation shield will span across the OH Valley, Mid-Atlantic,=20
    and Northeast with excessive amounts of wintry precipitation=20
    falling. While there remains some question on precipitation type,=20
    the ECMWF EFI shows the QPF is >0.8 from the Southern Plains and=20
    Mid-South to the Northeast, implying an unusually high amount of=20
    QPF for this time of year will be at this winter storm's disposal=20
    as it falls into a bitterly cold Arctic air-mass.=20

    Heavy Snow/Sleet...

    The latest forecast calls an astonishingly long swath (over 2,000=20
    mile long in length) of >6" of snowfall that starts in the Sangre=20
    De Cristo and Sacramento mountains of New Mexico all the way to=20
    Downeast Maine. It is worth noting that the snowfall probabilities=20
    being referenced will have snow and sleet. Focusing on the Plains=20
    first, WPC probabilities sport high chances (>70%) for snowfall >8"
    over central OK, southeast KS, southwest MO, and northwest AR.=20
    There is another impressive swath of high chance probabilities=20
    70%) for >8" of snow from southern IN and north-central KY to=20
    eastern Maine. The Central Appalachians, interior Northeast, and=20
    southern New England are likely to see the most snowfall with high=20
    chances (>70%) for over a foot of snow in these areas. In fact, WPC probabilities show low-to-moderate chances (30-50%) for totals=20
    over 18" in the Catskills, Berkshires, and eastern MA. Farther=20
    south, the inclusion of sleet from NY and Long Island southward=20
    along the I-95 corridor will likely cut into snowfall totals.=20 Climatologically speaking, areas west of I-95 where topography=20
    increases are most likely to see more snow than sleet. This is=20
    evident in the >8" for snow and sleet probabilities where they are=20
    high (>70% chances) from northwest VA and north-central MD along=20
    Parrs Ridge to the Lower Susquehanna Valley, but below 50% over=20
    southern NJ, the MD eastern shore, and south of Fredericksburg, VA.
    Still, the WSO shows >50% chances for a warning-level snowfall as=20
    far south as central VA on east through the northern DelMarVa and=20
    into southern NJ due to the strong 850-700mb FGEN Saturday night=20
    and Sunday morning that fosters snowfall rates that could ranges
    between 1-2"/hr. So while snowfall/sleet totals are not quite as=20
    high as their neighbors to the north, the combination of snow,=20
    sleet, and inclusion of some freezing rain still support=20
    significant travel disruptions in these southern areas as well.=20

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the TX
    Panhandle on east to the Ozarks, through the OH Valley, and all the
    way to New England. Every major market along the I-95 metropolitan
    corridor (Washington D.C. to Boston and even as far north as
    Portland, ME) are expecting major impacts due to snow. The=20
    D.C/Baltimore area on north to Philly and NYC are likely to see=20
    some inclusion of sleet, but it will still result in significant=20
    impacts when accounting for heavy snowfall that is expected to
    exceed warning criteria (5-6"). A reminder that bitterly cold=20
    temperatures will follow in wake of this storm Monday and into the=20
    middle of the week throughout the eastern U.S.. The snow/sleet=20
    impacts will linger well into next week with rounds of re-freezing=20
    that keeps surfaces icy and dangerous to both drive and walk on for
    the foreseeable future. Those in the path of this storm should=20
    make final preparations and put plans in place for significant=20
    travel disruptions this weekend and into at least early next week.


    Freezing Rain:

    The most lasting and dangerous impact will come as a result of=20
    significant to locally catastrophic ice accumulations due to=20
    prolonged periods of freezing rain. Just like the swath of >6" of=20
    snowfall, the areal coverage of high chances (>50%) in WPC's ice=20 probabilities exceeding one-quarter inch of ice accumulation is=20
    both impressive and alarming. From east-central TX to southern AR,=20
    northern LA, northern MS, the TN Valley, northern GA, the southern=20 Appalachians, and southern Mid-Atlantic, these regions are all=20
    likely to experience anywhere from one-quarter to one-half inch of=20
    ice. Widespread power outages and tree damage is likely in these=20
    areas, especially from the Lower MS Valley, southern Appalachians,=20
    and central NC where there are also high chances (>70%) for ice=20 accumulations over one-half inch. It is parts of northern AL,=20
    northern MS, south-central TN, far northern GA, the southern=20
    Appalachians, and the NC Piedmont that are of greatest concern.=20
    WPC probabilities show low-to-moderate chances (20-40%) for ice=20 accumulations over 1 inch. These areas are likely to endure a=20
    crippling ice storm that will take days, if not weeks, of clean up=20
    in addition to extended power outages. Residents in these areas=20
    should take final preparations now. Once the freezing rain starts,=20
    dangerous travel will be common not only during the event, but in=20
    the days in wake of the storm due to prolonged sub-freezing=20
    temperatures that cause persistent re-freezing on all untreated=20
    surfaces. The Key Messages for the Extreme Cold are linked below
    (Key Message 1).

    Farther east, freezing rain will reach southern VA, the DelMarVa
    Peninsula, and as far north as southern NJ. The southern VA
    Piedmont, including the Richmond metro area, have moderate chances
    (40-60%) for over one-half inch of ice. The WSSI depicts Major=20
    Impacts from Richmond on south along I-95 into NC, while Moderate=20
    Impacts (hazardous travel conditions) are anticipated as far north=20
    as the northern DelMarVa Peninsula and into the Lower Delaware=20
    Valley. While most areas farther north towards the Lower Delaware=20
    Valley and southern NJ should largely remain sleet, it may=20
    transition to freezing rain for a brief time by Sunday evening. WPC probabilities show low-to-moderate chances (30-50%) for over one-=20
    tench of an inch of ice accumulations Sunday evening.


    Key Messages for this system are linked below (Key Message 2)


    Mullinax



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!8GUWGIKvjpbH7j06LCzf76dgj7wKmpMcynczXffJXXaY-= mNp6L2dr8o-PiAMPcRJ2YyFHPbCmPdKNKW5sTA1hXXuSxM$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!8GUWGIKvjpbH7j06LCzf76dgj7wKmpMcynczXffJXXaY-= mNp6L2dr8o-PiAMPcRJ2YyFHPbCmPdKNKW5sTA1nTFVkNQ$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_3.png__;!!DZ3fjg!8GUWGIKvjpbH7j06LCzf76dgj7wKmpMcynczXffJXXaY-= mNp6L2dr8o-PiAMPcRJ2YyFHPbCmPdKNKW5sTA1sbzsBKw$=20



    $$

    =3D =3D =3D
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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, January 23, 2026 21:03:54
    FOUS11 KWBC 232103
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    403 PM EST Fri Jan 23 2026

    Valid 00Z Sat Jan 24 2026 - 00Z Tue Jan 27 2026


    ...Major winter storm to bring the potential for crippling icing,=20 significant sleet, and heavy snow from the Southern Plains through=20
    the Southeast and up the Atlantic Coast into New England...

    Meteorological Overview...

    A massive winter storm, set to produce a swath of heavy snow and=20
    dangerous ice accumulations, has begun today as tropical East=20
    Pacific moisture streams out ahead of the 500mb closed low near the
    Baja Peninsula. This moisture plume is clashing with the coldest=20
    air-mass of the season, entrenching itself over the Nation's=20
    Heartland. The moisture transport is exceptional with an
    integrated vapor transport (IVT) above the 97.5 climatological=20
    percentile per ECMWF SATs. The rich moisture from the south will=20
    accompany strong 850-700mb WAA that results in classic over-runing=20
    along a developing area of 850-700mb FGEN atop the Southern Plains.
    Meanwhile, the upper trough in the Southwest and an emerging=20
    upper- level shortwave trough over the Dakotas will strengthen a=20
    250mb jet streak over the east-central U.S., placing its thermally-
    direct right-entrance region over the Southern Plains. This=20
    synoptic- scale setup helps to enhance the mesoscale below,=20
    fostering heavy bands of snow and even elevated instability above=20
    the low-level sub-freezing layer over north TX on east into the=20
    Mid-South tonight and into Saturday.

    By Saturday, as the upper low near Baja approaches Texas, its=20
    associated jet streak over Mexico will co-locate its divergent=20
    left-exit region over the Mid-South and maximize upper-level ascent
    over the region. The IVT in advance of the upper trough over=20
    Mexico is both expansive and strong with >90th climatological=20
    percentile IVT values originating south of Mexico and extending all
    the way to the Southern Appalachians by Saturday afternoon. The=20
    remarkable extent of the IVT and the slow progression of the Mexico
    trough is why parts of the South and Mid-Atlantic are likely to=20
    see snow, sleet, and freezing rain for over 24 hours and in some=20
    cases approaching 48 hours. As arctic high pressure slides east, a=20
    cold-air damming (CAD) signature will become well pronounced along=20
    and east of the Appalachians as anomalous Pacific and Gulf moisture
    arrives, leading to precipitation falling into the frigid air-mass
    and supporting heavy snow, sleet, and freezing rain totals from=20
    the southern Appalachians to the Mid-Atlantic.=20

    Saturday night and into Sunday is where most changes in the
    forecast have unfolded of late. It remains unclear just how strong
    the emerging area of low pressure near the Gulf Coast will be and=20
    how far north it gets. It is noteworthy that guidance is in good=20
    agreement on 700mb Q-vector convergence over northern AL and the=20
    southern Appalachians, but the GFS is a little farther south in=20
    positioning while the ECMWF is a littler farther north and=20
    stronger, resulting in the northern shifts over the last couple=20
    days. What they do both agree on is by Sunday, a very pronounced=20
    area of strong 700mb Q-vector convergence will unfold along the=20
    Mid-Atlantic coast, prompting the development of a coastal low=20
    along a strengthening coastal front. With the benefit of the 250mb
    jet streak's divergent right-entrance region aloft and the=20
    strengthening IVT (ECMWF SATs show >99.5 climatological percentile=20
    values over the Southeast Sunday morning), an expansive=20
    precipitation shield will span across the OH Valley, Mid-Atlantic,=20
    and Northeast with excessive amounts of wintry precipitation=20
    falling. While there remains some question on precipitation type,=20
    the ECMWF EFI shows the QPF is >0.8 from the Southern Plains and=20
    Mid-South to the Northeast, implying an unusually high amount of=20
    QPF for this time of year will be at this winter storm's disposal=20
    as it falls into a bitterly cold Arctic air-mass.=20

    Heavy Snow/Sleet...

    The latest forecast calls an astonishingly long swath (over 2,000=20
    mile long in length) of >6" of snowfall that starts in the Sangre=20
    De Cristo and Sacramento mountains of New Mexico all the way to=20
    Downeast Maine. It is worth noting that the snowfall probabilities=20
    being referenced will have snow and sleet. Focusing on the Plains=20
    first, WPC probabilities sport high chances (>70%) for snowfall >8"
    over central OK, southeast KS, southwest MO, and northwest AR.=20
    There is another impressive swath of high chance probabilities=20
    70%) for >8" of snow from southern IN and north-central KY to=20
    eastern Maine. The Central Appalachians, interior Northeast, and=20
    southern New England are likely to see the most snowfall with high=20
    chances (>70%) for over a foot of snow in these areas. In fact, WPC probabilities show low-to-moderate chances (30-50%) for totals=20
    over 18" in the Catskills, Berkshires, and eastern MA. Farther=20
    south, the inclusion of sleet from NY and Long Island southward=20
    along the I-95 corridor will likely cut into snowfall totals.=20 Climatologically speaking, areas west of I-95 where topography=20
    increases are most likely to see more snow than sleet. This is=20
    evident in the >8" for snow and sleet probabilities where they are=20
    high (>70% chances) from northwest VA and north-central MD along=20
    Parrs Ridge to the Lower Susquehanna Valley, but below 50% over=20
    southern NJ, the MD eastern shore, and south of Fredericksburg, VA.
    Still, the WSO shows >50% chances for a warning-level snowfall as=20
    far south as central VA on east through the northern DelMarVa and=20
    into southern NJ due to the strong 850-700mb FGEN Saturday night=20
    and Sunday morning that fosters snowfall rates that could ranges
    between 1-2"/hr. So while snowfall/sleet totals are not quite as=20
    high as their neighbors to the north, the combination of snow,=20
    sleet, and inclusion of some freezing rain still support=20
    significant travel disruptions in these southern areas as well.=20

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the TX
    Panhandle on east to the Ozarks, through the OH Valley, and all the
    way to New England. Every major market along the I-95 metropolitan
    corridor (Washington D.C. to Boston and even as far north as
    Portland, ME) are expecting major impacts due to snow. The=20
    D.C/Baltimore area on north to Philly and NYC are likely to see=20
    some inclusion of sleet, but it will still result in significant=20
    impacts when accounting for heavy snowfall that is expected to
    exceed warning criteria (5-6"). A reminder that bitterly cold=20
    temperatures will follow in wake of this storm Monday and into the=20
    middle of the week throughout the eastern U.S.. The snow/sleet=20
    impacts will linger well into next week with rounds of re-freezing=20
    that keeps surfaces icy and dangerous to both drive and walk on for
    the foreseeable future. Those in the path of this storm should=20
    make final preparations and put plans in place for significant=20
    travel disruptions this weekend and into at least early next week.


    Freezing Rain...

    The most lasting and dangerous impact will come as a result of=20
    significant to locally catastrophic ice accumulations due to=20
    prolonged periods of freezing rain. Just like the swath of >6" of=20
    snowfall, the areal coverage of high chances (>50%) in WPC's ice=20 probabilities exceeding one-quarter inch of ice accumulation is=20
    both impressive and alarming. From east-central TX to southern AR,=20
    northern LA, northern MS, the TN Valley, northern GA, the southern=20 Appalachians, and southern Mid-Atlantic, these regions are all=20
    likely to experience anywhere from one-quarter to one-half inch of=20
    ice. Widespread power outages and tree damage is likely in these=20
    areas, especially from the Lower MS Valley, southern Appalachians,=20
    and central NC where there are also high chances (>70%) for ice=20 accumulations over one-half inch.=20

    It is parts of northern AL, northern MS, south-central TN, far=20
    northern GA, the southern Appalachians, and the NC Piedmont that=20
    are of greatest concern. WPC probabilities show low-to-moderate=20
    chances (20-40%) for ice accumulations over 1 inch. These areas are
    likely to endure a crippling ice storm that will take days, if not
    weeks, of clean up in addition to extended power outages. This is=20 demonstrated in a rare Extreme Impact on the WSSI in parts of
    northern MS, far southern TN, and the Southern Appalachians. The
    WSSI Extreme criteria references the potential for "extensive and=20
    widespread closures, extremely dangerous travel, and life-saving=20
    actions may be needed." Residents in these all referenced regions=20
    above should take final preparations now. Once the freezing rain=20
    starts, dangerous travel will be common not only during the event,=20
    but in the days in wake of the storm due to prolonged sub-freezing=20 temperatures that cause persistent re-freezing on all untreated=20
    surfaces. The Key Messages for the Extreme Cold are linked below=20
    (Key Message 1).

    Farther east, freezing rain will reach southern VA, the DelMarVa
    Peninsula, and as far north as southern NJ. The southern VA
    Piedmont, including the Richmond metro area, have moderate chances
    (40-60%) for over one-half inch of ice. The WSSI depicts Major=20
    Impacts from Richmond on south along I-95 into NC, while Moderate=20
    Impacts (hazardous travel conditions) are anticipated as far north=20
    as the northern DelMarVa Peninsula and into the Lower Delaware=20
    Valley. While most areas farther north towards the Lower Delaware=20
    Valley and southern NJ should largely remain sleet, it may=20
    transition to freezing rain for a brief time by Sunday evening. WPC probabilities show low-to-moderate chances (30-50%) for over one-=20
    tench of an inch of ice accumulations Sunday evening.


    Key Messages for this system are linked below (Key Message 2)


    Mullinax




    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!8yFFARuqbgrlMXfpwPGS4uJRxeJOXQOZNw6H1nZpRTRha= rrS6kEy-awMjMQhdY74aJIFWgelYkKRsYNo7so9y2A1flY$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!8yFFARuqbgrlMXfpwPGS4uJRxeJOXQOZNw6H1nZpRTRha= rrS6kEy-awMjMQhdY74aJIFWgelYkKRsYNo7so9tj5CnIA$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_3.png__;!!DZ3fjg!8yFFARuqbgrlMXfpwPGS4uJRxeJOXQOZNw6H1nZpRTRha= rrS6kEy-awMjMQhdY74aJIFWgelYkKRsYNo7so9VdC50ig$=20



    $$

    =3D =3D =3D
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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, January 24, 2026 08:38:44
    FOUS11 KWBC 240838
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    338 AM EST Sat Jan 24 2026

    Valid 12Z Sat Jan 24 2026 - 12Z Tue Jan 27 2026


    ...Ongoing major winter storm to bring the potential for crippling
    icing, significant sleet, and heavy snow from the Southern
    Rockies/Plains through the Southeast and up the Atlantic Coast=20
    into New England...

    Meteorological Overview...

    Forecast remains on track as a massive winter storm, set to=20
    produce a swath of heavy snow and dangerous ice accumulations, has=20
    begun across the southern Rockies and Plains as tropical East=20
    Pacific moisture streams out ahead of the 500mb closed low near the
    Baja Peninsula. This moisture plume is clashing with the coldest=20
    air- mass of the season, entrenching itself over the Nation's=20
    Heartland. The moisture transport is exceptional with an integrated
    vapor transport (IVT) above the 97.5 climatological percentile per
    ECMWF SATs. The rich moisture from the south will accompany strong
    850-700mb WAA that results in classic over-runing along an area of
    850-700mb FGEN stretching from atop the Southern Plains to the TN=20
    VLY and southern Mid-Atlantic by tonight. Meanwhile, the upper=20
    trough in the Southwest and an emerging upper- level shortwave=20
    trough over the Dakotas will strengthen a zonally oriented 250mb=20
    jet streak over the east- central U.S., placing its thermally-=20
    direct right- entrance region over the Southern Plains and Mid-=20
    South. This synoptic- scale setup helps to enhance the mesoscale=20
    below, fostering heavy bands of snow and even elevated instability=20
    above the low-level sub- freezing layer over north TX on east into=20
    the Mid-South today.

    As the upper low near Baja approaches Texas by tonight, its=20
    associated jet streak over Mexico will co-locate its divergent=20
    left-exit region over the southern Plains and Mid-South, maximizing=20
    upper- level ascent over the region. The IVT in advance of the=20
    upper trough over Mexico is both expansive and strong with >90th=20 climatological percentile IVT values originating south of Mexico=20
    and extending all the way to the Southern Appalachians by Saturday=20 afternoon. The remarkable extent of the IVT and the slow=20
    progression of the Mexico trough is why parts of the South and Mid-
    Atlantic are likely to see snow, sleet, and freezing rain for over
    24 hours and in some cases approaching 48 hours. As arctic high=20
    pressure slides east, a substantial cold- air damming (CAD)=20
    signature will become well pronounced along and east of the=20
    Appalachians as anomalous Pacific and Gulf moisture arrives,=20
    leading to precipitation falling into the frigid air-mass and=20
    supporting heavy snow, sleet, and freezing rain totals from the=20
    southern Appalachians to the Mid-Atlantic.=20

    Saturday night (tonight) into Sunday is when this event truly=20
    starts to peak in expansiveness and magnitude with wintry=20
    precipitation continuously spanning from New Mexico to the=20
    Northeast. Given the event is now well within the short range and=20
    the synoptic pattern is locked into place, uncertainty now mostly=20
    lies within the thermodynamics and both the depth as well as=20
    latitudinal reach of the mid-level warm nose. Depending on which=20
    CAM or global guidance you look at, this warm nose still has about=20
    100 miles of uncertainty. This uncertainty is most notable where=20
    WAA is strongest, throughout the Mid-Atlantic and into the=20
    Northeast Saturday night into Sunday. Here, the NAM3k and RRFS=20
    remain the farthest north and GFS/FV3 farthest south. WPC=20
    preference tonight was in the middle, somewhere between the CMC-=20
    Regional and NAM3k with how far north mixing would reach. What all=20
    models do both agree on is by Sunday, a very pronounced area of=20
    strong 700mb Q-vector convergence will unfold along the Mid-=20
    Atlantic coast, prompting the development of a coastal low along a=20 strengthening coastal front. With the benefit of the 250mb jet=20
    streak's divergent right- entrance region aloft and the=20
    strengthening IVT (ECMWF SATs show >99.5 climatological percentile=20
    values over the Southeast Sunday morning), an expansive=20
    precipitation shield will span across the OH Valley, Mid-Atlantic,=20
    and Northeast with excessive amounts of wintry precipitation=20
    falling. While there remains some question on precipitation type,=20
    NBM probabilities for >1.0" of QPF for the this event are greater=20
    than 70% from the Southern Plains to southern New England, implying
    a high amount of QPF that will be at this winter storm's disposal.


    Heavy Snow/Sleet...

    The latest forecast calls an astonishingly long swath (over 2,000=20
    mile long in length) of >6" of snowfall that starts in the Sangre=20
    De Cristo and Sacramento mountains of New Mexico all the way to=20
    Downeast Maine. It is worth noting that the snowfall probabilities=20
    being referenced will have snow and sleet and not include snowfall
    already fallen prior to 12Z Saturday (this morning). Focusing on=20
    the Plains first, WPC probabilities sport medium chances (50-70%%)
    for snowfall >8" over the TX Panhandle, central OK, southern MO,
    and northern AR. There is another impressive swath of high chance=20 probabilities (>70%) for >8" of snow from southern IL/IN and=20
    north- central KY to eastern Maine. The Central Appalachians,=20
    interior Northeast, and southern New England are likely to see the=20
    most snowfall with high chances (>70%) for over a foot of snow in=20
    these areas. In fact, WPC probabilities show low- to-moderate=20
    chances (30-50%) for totals over 18" in the Catskills, Berkshires,=20
    and eastern MA to the southern coast of ME. Farther south, the=20
    inclusion of sleet from the LI sound southward along the I-95=20
    corridor will likely cut into snowfall totals. Climatologically=20
    speaking, areas west of I-95 where topography increases are most=20
    likely to see more snow than sleet. This is evident in the >8" for=20
    snow and sleet probabilities where they are high (>70% chances)=20
    from northwest VA and north- central MD along Parr's Ridge to the=20
    Lower Susquehanna Valley, but below 50% over southern NJ, the MD=20
    eastern shore, and south of Fredericksburg, VA. Still, the WSO=20
    shows >50% chances for a warning-level snowfall as far south as=20
    central VA on east through the northern DelMarVa and into southern=20
    NJ due to the strong 850-700mb FGEN Saturday night and Sunday=20
    morning that fosters snowfall rates that could ranges between=20
    1-2"/hr just north of the warm nose and changeover to sleet. This=20
    FGEN is so strong in several CAMs as it lifts northward into the=20
    Northeast on Sunday, mostly in part to the extreme thermal=20
    gradient in place, that a few instances of thundersnow shouldn't=20
    be ruled out. Even for areas that don't remain 100 percent snow,=20
    the combination of snow, sleet, and inclusion of some freezing rain
    still support significant travel disruptions in these southern=20
    areas as well.=20

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the TX
    Panhandle on east to the Ozarks, through the OH Valley, and all the
    way to New England. Every major market along the I-95 metropolitan
    corridor (Washington D.C. to Boston and even as far north as
    Portland, ME) are expecting major impacts due to snow. The=20
    D.C/Baltimore area on north to Philly and NYC are likely to see=20
    some inclusion of sleet, but it will still result in significant=20
    impacts when accounting for heavy snowfall that is expected to
    exceed warning criteria (5-6"). Coastal New England, including the
    Boston metro region could also see winds increase to near-blizzard
    conditions as wind gusts increase to 30-40 mph due to the
    strengthening surface low and continued high snowfall rates. A=20
    reminder that bitterly cold temperatures will follow in wake of=20
    this storm Monday and into the middle of the week throughout the=20
    eastern U.S.. The snow/sleet impacts will linger well into next=20
    week with rounds of re-freezing that keeps surfaces icy and=20
    dangerous to both drive and walk on for the foreseeable future.=20
    Those in the path of this storm should follow advice of local
    officials.


    Freezing Rain...

    The most lasting and dangerous impact will come as a result of=20
    significant to locally catastrophic ice accumulations due to=20
    prolonged periods of freezing rain. Just like the swath of >6" of=20
    snowfall, the areal coverage of high chances (>50%) in WPC's ice=20 probabilities exceeding one-quarter inch of ice accumulation is=20
    both impressive and alarming. From east-central TX to southern AR,=20
    northern LA, northern MS, the TN Valley, northern GA, the southern=20 Appalachians, and southern Mid-Atlantic, these regions are all=20
    likely to experience anywhere from one-quarter to one-half inch of=20
    ice. Widespread power outages and tree damage is likely in these=20
    areas, especially from the Lower MS Valley, southern Appalachians,
    central NC, and south-central VA, where there are also medium=20
    chances (>50%) for ice accumulations over one-half inch.=20

    It is parts of northwest AL, northern MS, south-central TN,
    southeast AR, northern LA, far northern GA, the southern=20
    Appalachians, and the NC Piedmont that are of greatest concern. WPC probabilities show low- to- moderate chances (20-40%) for ice=20
    accumulations over 1 inch and higher probabilities (30-60%) across
    parts of northern/northwestern MS. These areas are likely to=20
    endure a crippling ice storm that will take days, if not weeks, of=20
    clean up in addition to extended power outages while bitterly cold
    temperatures linger into next week. This is demonstrated in a rare
    Extreme Impact on the WSSI in parts of northern MS, northeast LA, and
    the Southern Appalachians. The WSSI Extreme criteria references=20
    the potential for "extensive and widespread closures, extremely=20
    dangerous travel, and life- saving actions may be needed." Once=20
    the freezing rain starts, dangerous travel will be common not only=20
    during the event, but in the days in wake of the storm due to=20
    prolonged sub- freezing temperatures that cause persistent re-=20
    freezing on all untreated surfaces. The Key Messages for the=20
    Extreme Cold are linked below (Key Message 1).

    Farther east, freezing rain will reach southern VA, the DelMarVa
    Peninsula, and as far north as the I-95 corridor from Washington
    D.C. to Philadelphia. The southern VA Piedmont, including the=20
    Richmond metro area, have medium chances (40-60%) for over one-=20
    half inch of ice. The WSSI depicts Major Impacts from Richmond on=20
    south along I-95 into NC. While most areas farther north towards=20
    the Lower Delaware Valley, Washington D.C. into southern NJ should
    largely remain sleet, it may transition to freezing rain for a=20
    brief time by Sunday evening. WPC probabilities show low-to-=20
    medium chances (30-60%) for over one- tench of an inch of ice=20
    accumulations Sunday evening.


    Key Messages for this system are linked below (Key Message 2)


    Snell/Mullinax



    ...Extreme Cold & Winter Storm Key Messages are in effect. Please=20
    see current Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_vSUFosL_fNE974CSds0-9HtYtuDLS1ao9damo__bVfhY= Taja5j4kl65r1blGHh-4akoePTGVmNbnc9HyIXEP5PejZs$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_vSUFosL_fNE974CSds0-9HtYtuDLS1ao9damo__bVfhY= Taja5j4kl65r1blGHh-4akoePTGVmNbnc9HyIXELnzOa_o$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, January 24, 2026 20:08:33
    FOUS11 KWBC 242008
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    308 PM EST Sat Jan 24 2026

    Valid 00Z Sun Jan 25 2026 - 00Z Wed Jan 28 2026


    ...Ongoing major winter storm to bring crippling icing,=20
    significant sleet, and heavy snow from the Southern Rockies/Plains=20
    through the Southeast and up the Atlantic Coast into New England...

    Meteorological Overview...
    Forecast remains on track as a massive winter storm, set to=20
    produce a swath of heavy snow, significant sleet, and dangerous ice accumulations, continues across the Southern Plains and begins to=20
    expand into the Ohio and Tennessee Valleys this afternoon. By=20
    tonight, wintry precipitation is expected to lift into the Mid-=20
    Atlantic, and reach New England on Sunday. By the time this event=20
    winds down late Monday, it will leave a trail of more than 2000=20
    miles of wintry precipitation, in a nearly continuous path, from=20
    New Mexico to Maine.

    The driver of this event will be the interaction of a northern
    stream trough diving out of Canada with a southern stream impulse
    ejecting from near Baja California. As these features move eastward
    through the weekend and interact into a more amplified and larger
    trough over the eastern CONUS, impressive subtropical moisture=20
    will spread east/northeast both from the Pacific and the Gulf, with
    IVT exceeding the 97th climatological percentile according to
    NAEFS. The rich moisture from the south will accompany strong=20
    850-700mb WAA that results in classic over-runing along an area of=20
    850-700mb FGEN stretching from atop the Southern Plains to the TN=20
    VLY and southern Mid-Atlantic by tonight, reaching New England
    Sunday, and then finally exiting the Atlantic Coast on Monday. In
    addition to the classic overrunning/WAA precipitation, the
    placement of the upper jet as it strengthens and pivots poleward,
    will support intense bands of snowfall (cross sections suggest a
    high threat for CSI and even potential CI within the strongest WAA)
    which will support snowfall rates of 1-2+"/hr at times where it is
    all snow, and intense sleet/freezing rain rates in mixed zones.

    Farther to the east, an intense CAD (Cold Air Damming) signature=20
    will develop east of the Appalachians, with intense dewpoint
    depressions of 20-30F during precipitation overrunning. While it
    will take a while to saturate this to result in precipitation at
    the surface, the intensity of this high with cold isallobaric
    drainage aided both by mid-level confluence to the north and
    precipitation falling into this wedge will enhance the CAD and
    result in long duration mixed precipitation as the WAA pushes a
    warm nose aloft (generally 800-700mb). This will support heavy
    icing and sleet lifting northward into the Mid-Atlantic on Sunday,
    and potentially as far as the south coast of New England as well.

    With intense IVT pushing PWs to above the 99th percentile, there
    will be plentiful moisture to work with everywhere from Texas
    through New England. This will support heavy precipitation
    accumulations regardless of p-type, so substantial impacts are
    expected for a large swath of the nation. The heaviest snow is
    expected from the Ohio Valley into the Northeast (more outlined
    below), but an impressive jet-forced band of snow is also likely
    from the Texas Panhandle through the Mid-Mississippi Valley.
    Farther south, crippling icing is expected for parts of
    AR/LA/MS/TN, as well as the Carolinas, with exceptional sleet
    accumulations of several inches progged in between the snow and ice
    from Arkansas through Kentucky, and then for portions of the Mid-
    Atlantic as well.\


    Heavy Snow/Sleet...
    Snow will be winding down across the Southern Plains after 00Z=20
    this evening (the start of the forecast period) but remain across=20
    NM and of course farther east into AR/MO. This still supports an=20 astonishingly long swath of >6" of snowfall from NM to ME.=20

    =46rom the Southern Plains through the Ohio Valley, 72-hr WPC
    probabilities (so the entire forecast period although snowfall
    should generally be a 24-hr period, a heavy band of snowfall on the
    NW side of the low and within the strengthening jet streak will
    support 1+"/hr snowfall as reflected by the WPC prototype snowband
    tool. With this band likely translating along its long axis, heavy
    snowfall will have a temporal extent sufficient for more than 8
    inches (30-50% chance from the TX Panhandle through SW MO,
    increasing to 90%+ in the Ohio Valley where more than 12 inches is
    also likely (50-70% chance) before snow wanes from SW to NE on
    Sunday. Locally 15+ inches is possible across southern OH.=20

    The heaviest snow is likely from Pennsylvania through New England
    where p-type changes are not likely. This is also where the longest
    duration of heavy snowfall within both WAA banded structures and
    then potentially a more pivoting/translating band will develop as
    secondary low pressure skirts off the Mid-Atlantic coast and just
    inside the Benchmark (40N/70W). This will support a longer
    duration of 1-2+"/hr snowfall, and WPC 72-hr probabilities reach
    above 70% for 12+ inches, and locally as much as 2 feet is possible
    (especially in the Worcester Hills, Berkshires, and Catskills, as
    well north of Boston along the coastal front) where WPC
    probabilities for 24" are 10-30%. However, this will be a
    widespread 12+" snowfall event for most of southern and central New
    England as well as PA.

    In addition, with the intense WAA, a warm nose aloft (generally
    800-700mb) will gradually create a warm nose above 0C shifting
    through the Mid-Atlantic, with additional warm nose/sleet impacts
    expected from AR and into TN and KY. The cold depth below this warm
    nose appears to be in many places above the 75th-90th percentile
    for freezing rain, indicating primary sleet for these areas as
    p-type transition occurs, with significant sleet accumulations of multiple-inches expected. This will result in tremendous impacts to
    travel in these areas.

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the TX
    Panhandle on east to the Ozarks, through the OH Valley, and all the
    way to New England. Every major market along the I-95 metropolitan
    corridor (Washington D.C. to Boston and even as far north as
    Portland, ME) are expecting major impacts due to snow. The=20
    D.C/Baltimore area on north to Philly and NYC are likely to see=20
    some inclusion of sleet, but it will still result in significant=20
    impacts when accounting for heavy snowfall that is expected to
    exceed warning criteria (5-6"). A reminder that bitterly cold=20
    temperatures will follow in wake of this storm through the middle=20
    of next week throughout the eastern U.S., so snow/sleet impacts=20
    will linger for many days even after precipitation ends.


    Freezing Rain...
    The most lasting impact will come as a result of significant to=20
    locally catastrophic ice accumulations due to prolonged periods of=20
    freezing rain. Just like the swath of >6" of snowfall, the areal=20
    coverage of high chances (>50%) in WPC's ice probabilities=20
    exceeding one-quarter inch of ice accumulation is expansive from=20
    eastern TX through southern KY, with a secondary area east of the=20
    Cumberland Gap from northern GA through southeast VA and including=20
    much of the Carolinas. In these regions, at least 0.25" of ice is=20
    expected to be widespread, with a more narrow corridor embedded=20
    within of at least 0.5" (50-90%), highest in northern MS and=20
    western TN, but some higher potential also exists in GA/SC where=20
    locally more than 1 inch (a catastrophic accumulation for damage=20
    and prolonged impacts of a week or more) is possible (10-30%=20
    chance).

    For LA, MS, TN, this ice accumulation is "additional" beyond what
    will occur before 00Z (6pm CST), so local amounts above 1" are
    actually expected to be more widespread than the updated
    probabilities suggest. This produces a 20-40% chance of Extreme
    impacts (extensive and widespread disruptions to infrastructure)
    and these impacts could linger for a week or more where icing is
    most significant. With very cold weather in place, this will become
    a life-threatening situation, with potentially impossible travel
    due to downed trees and power lines.


    Key Messages for this system are linked below (Key Message 2).
    Key messages for the widespread extreme cold are linked below as
    well (Key Message 1).


    ...Great Lakes...
    Day 3...

    Broad cyclonic flow will persist across the east, but an embedded
    shortwave within this trough will dig out of Alberta Monday night
    and then cross the Great Lakes from northwest to southeast during
    Tuesday. This will enhance CAA, leading to another round of lake
    effect snow (LES), although the duration and intensity of this
    event should be modest overall, some moderate accumulations are
    still expected beginning D3 /00Z Tuesday to 00Z Wednesday/ and
    lingering beyond this forecast period. LES from Lake Erie should be
    minimal as that lake is now ice covered according to GLERL, but
    elsewhere, ***WPC probs...heaviest***


    Snell/Weiss


    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5yyp-eYgnqjdhXbnMGZ5F6MbfMH3V2jDjKFhtuPp72HzG= v1utrZAGBCuWMZw740nbStEiOYlG4pGhUeyanMrSk83qWE$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!5yyp-eYgnqjdhXbnMGZ5F6MbfMH3V2jDjKFhtuPp72HzG= v1utrZAGBCuWMZw740nbStEiOYlG4pGhUeyanMrxvhmuX8$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, January 24, 2026 20:13:12
    FOUS11 KWBC 242013
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    313 PM EST Sat Jan 24 2026

    Valid 00Z Sun Jan 25 2026 - 00Z Wed Jan 28 2026


    ...Ongoing major winter storm to bring crippling icing,=20
    significant sleet, and heavy snow from the Southern Rockies/Plains=20
    through the Southeast and up the Atlantic Coast into New England...

    Meteorological Overview...
    Forecast remains on track as a massive winter storm, set to=20
    produce a swath of heavy snow, significant sleet, and dangerous ice accumulations, continues across the Southern Plains and begins to=20
    expand into the Ohio and Tennessee Valleys this afternoon. By=20
    tonight, wintry precipitation is expected to lift into the Mid-=20
    Atlantic, and reach New England on Sunday. By the time this event=20
    winds down late Monday, it will leave a trail of more than 2000=20
    miles of wintry precipitation, in a nearly continuous path, from=20
    New Mexico to Maine.

    The driver of this event will be the interaction of a northern
    stream trough diving out of Canada with a southern stream impulse
    ejecting from near Baja California. As these features move eastward
    through the weekend and interact into a more amplified and larger
    trough over the eastern CONUS, impressive subtropical moisture=20
    will spread east/northeast both from the Pacific and the Gulf, with
    IVT exceeding the 97th climatological percentile according to
    NAEFS. The rich moisture from the south will accompany strong=20
    850-700mb WAA that results in classic over-runing along an area of=20
    850-700mb FGEN stretching from atop the Southern Plains to the TN=20
    VLY and southern Mid-Atlantic by tonight, reaching New England
    Sunday, and then finally exiting the Atlantic Coast on Monday. In
    addition to the classic overrunning/WAA precipitation, the
    placement of the upper jet as it strengthens and pivots poleward,
    will support intense bands of snowfall (cross sections suggest a
    high threat for CSI and even potential CI within the strongest WAA)
    which will support snowfall rates of 1-2+"/hr at times where it is
    all snow, and intense sleet/freezing rain rates in mixed zones.

    Farther to the east, an intense CAD (Cold Air Damming) signature=20
    will develop east of the Appalachians, with intense dewpoint
    depressions of 20-30F during precipitation overrunning. While it
    will take a while to saturate this to result in precipitation at
    the surface, the intensity of this high with cold isallobaric
    drainage aided both by mid-level confluence to the north and
    precipitation falling into this wedge will enhance the CAD and
    result in long duration mixed precipitation as the WAA pushes a
    warm nose aloft (generally 800-700mb). This will support heavy
    icing and sleet lifting northward into the Mid-Atlantic on Sunday,
    and potentially as far as the south coast of New England as well.

    With intense IVT pushing PWs to above the 99th percentile, there
    will be plentiful moisture to work with everywhere from Texas
    through New England. This will support heavy precipitation
    accumulations regardless of p-type, so substantial impacts are
    expected for a large swath of the nation. The heaviest snow is
    expected from the Ohio Valley into the Northeast (more outlined
    below), but an impressive jet-forced band of snow is also likely
    from the Texas Panhandle through the Mid-Mississippi Valley.
    Farther south, crippling icing is expected for parts of
    AR/LA/MS/TN, as well as the Carolinas, with exceptional sleet
    accumulations of several inches progged in between the snow and ice
    from Arkansas through Kentucky, and then for portions of the Mid-
    Atlantic as well.\


    Heavy Snow/Sleet...
    Snow will be winding down across the Southern Plains after 00Z=20
    this evening (the start of the forecast period) but remain across=20
    NM and of course farther east into AR/MO. This still supports an=20 astonishingly long swath of >6" of snowfall from NM to ME.=20

    =46rom the Southern Plains through the Ohio Valley, 72-hr WPC
    probabilities (so the entire forecast period although snowfall
    should generally be a 24-hr period, a heavy band of snowfall on the
    NW side of the low and within the strengthening jet streak will
    support 1+"/hr snowfall as reflected by the WPC prototype snowband
    tool. With this band likely translating along its long axis, heavy
    snowfall will have a temporal extent sufficient for more than 8
    inches (30-50% chance from the TX Panhandle through SW MO,
    increasing to 90%+ in the Ohio Valley where more than 12 inches is
    also likely (50-70% chance) before snow wanes from SW to NE on
    Sunday. Locally 15+ inches is possible across southern OH.=20

    The heaviest snow is likely from Pennsylvania through New England
    where p-type changes are not likely. This is also where the longest
    duration of heavy snowfall within both WAA banded structures and
    then potentially a more pivoting/translating band will develop as
    secondary low pressure skirts off the Mid-Atlantic coast and just
    inside the Benchmark (40N/70W). This will support a longer
    duration of 1-2+"/hr snowfall, and WPC 72-hr probabilities reach
    above 70% for 12+ inches, and locally as much as 2 feet is possible
    (especially in the Worcester Hills, Berkshires, and Catskills, as
    well north of Boston along the coastal front) where WPC
    probabilities for 24" are 10-30%. However, this will be a
    widespread 12+" snowfall event for most of southern and central New
    England as well as PA.

    In addition, with the intense WAA, a warm nose aloft (generally
    800-700mb) will gradually create a warm nose above 0C shifting
    through the Mid-Atlantic, with additional warm nose/sleet impacts
    expected from AR and into TN and KY. The cold depth below this warm
    nose appears to be in many places above the 75th-90th percentile
    for freezing rain, indicating primary sleet for these areas as
    p-type transition occurs, with significant sleet accumulations of multiple-inches expected. This will result in tremendous impacts to
    travel in these areas.

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the TX
    Panhandle on east to the Ozarks, through the OH Valley, and all the
    way to New England. Every major market along the I-95 metropolitan
    corridor (Washington D.C. to Boston and even as far north as
    Portland, ME) are expecting major impacts due to snow. The=20
    D.C/Baltimore area on north to Philly and NYC are likely to see=20
    some inclusion of sleet, but it will still result in significant=20
    impacts when accounting for heavy snowfall that is expected to
    exceed warning criteria (5-6"). A reminder that bitterly cold=20
    temperatures will follow in wake of this storm through the middle=20
    of next week throughout the eastern U.S., so snow/sleet impacts=20
    will linger for many days even after precipitation ends.


    Freezing Rain...
    The most lasting impact will come as a result of significant to=20
    locally catastrophic ice accumulations due to prolonged periods of=20
    freezing rain. Just like the swath of >6" of snowfall, the areal=20
    coverage of high chances (>50%) in WPC's ice probabilities=20
    exceeding one-quarter inch of ice accumulation is expansive from=20
    eastern TX through southern KY, with a secondary area east of the=20
    Cumberland Gap from northern GA through southeast VA and including=20
    much of the Carolinas. In these regions, at least 0.25" of ice is=20
    expected to be widespread, with a more narrow corridor embedded=20
    within of at least 0.5" (50-90%), highest in northern MS and=20
    western TN, but some higher potential also exists in GA/SC where=20
    locally more than 1 inch (a catastrophic accumulation for damage=20
    and prolonged impacts of a week or more) is possible (10-30%=20
    chance).

    For LA, MS, TN, this ice accumulation is "additional" beyond what
    will occur before 00Z (6pm CST), so local amounts above 1" are
    actually expected to be more widespread than the updated
    probabilities suggest. This produces a 20-40% chance of Extreme
    impacts (extensive and widespread disruptions to infrastructure)
    and these impacts could linger for a week or more where icing is
    most significant. With very cold weather in place, this will become
    a life-threatening situation, with potentially impossible travel
    due to downed trees and power lines.


    Key Messages for this system are linked below (Key Message 2).
    Key messages for the widespread extreme cold are linked below as
    well (Key Message 1).


    ...Great Lakes...
    Day 3...

    Broad cyclonic flow will persist across the east, but an embedded
    shortwave within this trough will dig out of Alberta Monday night
    and then cross the Great Lakes from northwest to southeast during
    Tuesday. This will enhance CAA, leading to another round of lake
    effect snow (LES), although the duration and intensity of this
    event should be modest overall, some moderate accumulations are
    still expected beginning D3 /00Z Tuesday to 00Z Wednesday/ and
    lingering beyond this forecast period. LES from Lake Erie should be
    minimal as that lake is now ice covered according to GLERL, but
    elsewhere, WPC probabilities are moderate for 4+ inches near the
    Tug Hill Plateau, and moderate (10-50%)for 2+ inches along the=20
    western shore of the L.P. of MI as well as parts of the U.P.


    Snell/Weiss



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5W-O6S2TsavdXtQOUAK8oUfK4CWv9hDLB6maEn-RBEC8z= dxGx2_1hRti8HNuSE65ZONdrM6PSUgE9zjorHLbn-2g7N0$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!5W-O6S2TsavdXtQOUAK8oUfK4CWv9hDLB6maEn-RBEC8z= dxGx2_1hRti8HNuSE65ZONdrM6PSUgE9zjorHLbAtBCRDQ$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, January 25, 2026 07:41:52
    FOUS11 KWBC 250741
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    241 AM EST Sun Jan 25 2026

    Valid 12Z Sun Jan 25 2026 - 12Z Wed Jan 28 2026


    ...Ongoing major winter storm to bring crippling icing,=20
    significant sleet, and heavy snow from the Southern Rockies/Plains=20
    through the Southeast and up the Atlantic Coast into New England...

    Meteorological Overview...
    Forecast remains on track as a massive winter storm is underway
    across a significant portion of the country, currently extending=20
    from the southern Rockies to the Mid-Atlantic early this morning.
    By the start of the forecast period (12z Sun), widespread moderate
    to heavy snow, sleet, and freezing rain is expected to span from=20
    New Mexico to New York and continue to primarily impact regions=20
    from the Ohio/Tennessee valleys and Mid-Atlantic to New England
    through the overnight hours tonight. This event is forecast to=20
    gradually wane across New England and the Interior Northeast on=20
    Monday.

    The driver of this winter storm is the interaction of a northern=20
    stream trough diving out of the north-central U.S. this morning
    along with a few southern stream impulses ejecting from the
    southern Rockies and Plains. As these features accelerate eastward
    today and interact into a more amplified and larger trough over=20
    the central CONUS tonight, impressive subtropical moisture will
    continue spreading east/northeast both from the Pacific and the=20
    Gulf, with IVT exceeding the 97.5th climatological percentile=20
    according to NAEFS. The rich moisture from the south will accompany
    strong 850-700mb WAA that results in classic over- running along=20
    an area of 850-700mb FGEN stretching from atop the Mid-MS and OH/TN
    VLY to the Mid- Atlantic this morning, reaching New England this=20
    evening and then finally exiting the Atlantic Coast on Monday. In=20
    addition to the classic overrunning/WAA precipitation, the=20
    placement of the upper jet as it strengthens and pivots poleward,=20
    will support intense bands of snowfall (cross sections suggest a=20
    high threat for CSI and even potential CI within the strongest WAA)
    which will support snowfall rates of 1-2+"/hr at times where it is
    all snow, and intense sleet/freezing rain rates in mixed zones.

    Farther to the east, the intense CAD (Cold Air Damming) signature=20=20
    east of the Appalachians will only slightly retreat through
    tonight. With rapid warming aloft due to increasing southerly 850mb
    winds over 50 kts and subfreezing temperatures remaining in the=20
    low- levels, sleet is expected to be as far north as southern MD by
    12z this morning and continuing marching northward through the day
    as far as the southern New England coastline. This will cut down on
    snowfall totals along I-95 from Washington D.C. to NYC, and will
    also increase the potential for ptype to turn towards dangerous
    freezing rain by late this afternoon.

    With intense IVT pushing PWs to above the 99th percentile, there
    will be plentiful moisture to work with everywhere from the OH VLY
    through New England. This will support heavy precipitation=20
    accumulations regardless of p-type, so substantial impacts are=20
    expected for a large swath of the nation. The heaviest snow is=20
    expected from the Ohio Valley into the Northeast (more outlined=20
    below). Farther south, crippling icing is expected for parts of=20
    AR/LA/MS/TN early today, as well as the Carolinas and Virginia
    through tonight, with exceptional sleet accumulations of several=20
    inches progged in between the snow and ice from Arkansas through=20
    Kentucky, and then for portions of the Mid- Atlantic as well.


    Heavy Snow/Sleet...
    Snow will be winding down across the Southern Plains and Mid-MS VLY
    by 12z this morning, but continues just east through the OH VLY. This
    still supports an long swath of >6" of snowfall from IN to ME and
    an increasing potential for >18" across the Interior Northeast and
    New England.

    48-hr WPC probabilities (most snow occurring within the first=20
    24-hr period), are high (>70%) for an additional 8"+ from central=20
    OH through central ME and most of New England. Probabilities for=20
    18"+ have increased and are 50-80% across Upstate NY through much=20
    of New England as far north as central VT/NH. A heavy band of=20
    snowfall on the NW side of the low and within the strengthening jet
    streak will support 1+"/hr snowfall across the Ohio Valley through
    this afternoon as reflected by the WPC prototype snowband tool.=20
    With this band likely translating along its long axis, heavy=20
    snowfall will have a temporal extent sufficient for more than 8=20
    inches. Locally 15+ inches is possible across southern OH.=20

    The heaviest snow from this event is likely across New England and
    the Interior Northeast where p-type changes are not likely. This=20
    is also where the longest duration of heavy snowfall within both=20
    WAA banded structures and then potentially a more=20
    pivoting/laterally translating band will develop as secondary low=20
    pressure skirts off the Mid- Atlantic coast and just inside the=20
    Benchmark (40N/70W). This will support a longer duration of=20
    2+"/hr snowfall, and WPC 48-hr probabilities reach above 90% for=20
    12+ inches, and locally as much as 2 feet is possible (especially=20
    in the Worcester Hills, Berkshires, and Catskills, as well north of
    Boston along the coastal front) where WPC probabilities for 24"=20
    are 20-40%. WPC's Snowband Probability Tracker (SPT) using the 00z
    HREF is very impressive for 1-2"+/hr rates around 18Z near=20
    northern NJ and eventually across New England beginning around 21Z
    and lasting across eastern New England until 06Z tonight.=20
    Regarding coverage of heavy snow, this will be a widespread 12"+=20
    snowfall event for most of southern and central New England as well
    as central/northern PA.

    In addition, with the intense WAA, a warm nose aloft (generally
    800-700mb) will gradually create a warm nose above 0C shifting
    through the Mid-Atlantic. The cold depth below this warm nose=20
    appears to be in many places above the 75th-90th percentile for=20
    freezing rain, indicating primary sleet for these interior areas=20
    as p-type transition occurs, with significant sleet accumulations=20
    of multiple-inches expected. This will result in tremendous impacts
    to travel in these areas.

    The WSSI shows widespread Major Impacts (considerable disruptions
    to daily life: dangerous to impossible driving conditions,=20
    widespread closures, and disruptions to infrastructure) from the=20
    OH VLY to New England. Every major market along the I-95=20
    metropolitan corridor (Washington D.C. to Boston and even as far=20
    north as Portland, ME) are expecting major impacts due to snow
    amounts. The D.C/Baltimore area on north to Philly and NYC are=20
    likely to see some inclusion of sleet and potentially some freezing
    rain, but it will still result in significant impacts when=20
    accounting for heavy snowfall that is expected to exceed warning=20
    criteria (5-6"). Gusty winds increasing with the developing=20
    surface low off the Mid-Alantic coast may also lead to a brief=20
    period of near-blizzard conditions across eastern New England,=20
    including Boston, late tonight. A reminder that bitterly cold=20
    temperatures will follow in wake of this storm through the middle=20
    of next week throughout the eastern U.S., so snow/sleet impacts=20
    will linger for many days even after precipitation ends.

    Freezing Rain...
    The most lasting impact will come as a result of significant to=20
    locally catastrophic ice accumulations due to prolonged periods of=20
    freezing rain. Just like the swath of >6" of snowfall, the areal=20
    coverage of impactful freezing rain remains expansive across the=20
    Mid- South, where the event concludes by midday today and a=20
    secondary area east of the Cumberland Gap from northern GA through=20
    central VA and southern MD, including much of the Carolinas. In=20
    these regions, at least 0.25" of total ice is expected to be=20
    widespread, with a more narrow corridor embedded within of at least
    an additional 0.5" (30-60%), highest today across the NC Piedmont
    into south-central VA. This amount of freezing rain can create
    widespread power outages and tree damage, as well as treacherous to
    impossible travel at times.

    For LA, MS, TN, ice accumulation is "additional" beyond what will=20
    occur before 12Z (6am CST), so local amounts above 1" are actually
    expected to be much more widespread than the very low=20
    probabilities suggest for solely today's precipitation. The=20
    greatest additional icing after 12Z today is located across the=20
    Mid- Atlantic, where up to 0.5" is possible. With very cold weather
    in place, this will become a life- threatening situation where=20
    freezing rain amounts are highest (including the Lower MS VLY and=20
    Mid-South) with potentially impossible travel due to downed trees=20
    and power lines.


    Key Messages for this system are linked below (Key Message 2).
    Key messages for the widespread extreme cold are linked below as
    well (Key Message 1).


    ...Great Lakes...
    Days 2-3...

    Broad cyclonic flow will persist across the east, but an embedded
    shortwave within this trough will dig out of Alberta Monday night
    and then cross the Great Lakes from northwest to southeast during
    Tuesday. This will enhance CAA, leading to another round of lake
    effect snow (LES), although the duration and intensity of this
    event should be modest overall, some moderate accumulations are
    still expected beginning D2-3 and lingering beyond this forecast=20
    period. LES from Lake Erie should be minimal as that lake is now=20
    ice covered according to GLERL and should continue to see ice
    thicken with very cold temperatures in place, but elsewhere, WPC=20 probabilities are high for 4+ inches near the Tug Hill Plateau.


    Snell/Weiss




    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9sseXzdxj0AGHqtE9PxBDvpaCHTgyf0kBlV0VQClBi97u= cbSjEzZJILpGM3a97dsD08_MPYg2KvCXzcmJFn55hXmNHY$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!9sseXzdxj0AGHqtE9PxBDvpaCHTgyf0kBlV0VQClBi97u= cbSjEzZJILpGM3a97dsD08_MPYg2KvCXzcmJFn5V8ppWtM$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, January 25, 2026 18:20:25
    FOUS11 KWBC 251820
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    120 PM EST Sun Jan 25 2026

    Valid 00Z Mon Jan 26 2026 - 00Z Thu Jan 29 2026


    ...Mid-Atlantic and Northeast...
    Days 1-2...

    The expansive winter storm will wind down across the Central
    Plains and Mid-South today, but significant impacts will persist
    across the Ohio Valley, Mid-Atlantic, and Northeast tonight and
    Monday.

    This morning, the GOES-E water vapor imagery tells the take, with
    an impressive plume of moisture stretching from Texas into southern
    Canada, with a clear baroclinic leaf expanding over the TN/OH
    Valleys. The upper low is spinning over TX and this will lift
    northward into the Ohio Valley today, while secondary low pressure
    development occurs off the Mid-Atlantic coast this afternoon. This
    secondary low pressure will become dominant and strengthen as it
    tracks south of New England, with the most significant winter
    weather and impacts shifting into New England tonight and Monday.
    The trailing upper trough will move across the Great Lakes Monday,
    helping to drive an inverted trough back across New England even as
    the primary low departs, and light although the heaviest snow
    should end Monday night, light snow may persist in this area into
    Tuesday morning.=20

    This evolution will result in impressive additional snow amounts
    (after 00Z this evening) from the higher terrain of WV/PA northeast
    through Upstate NY and all of New England. The heaviest snowfall is
    expected across Upstate NY and New England where WPC probabilities
    indicate a high risk (>90%) for at least 8 inches, with 12-18"
    possible (30-50% chance) for the Greens, Whites, and coastal SW=20
    Maine/far northern MA thanks to a coastal front evolution. Snowfall
    rates will be extreme at times, potentially reaching 2-3"/hr as=20
    progged by the WPC prototype snowband tool due to strong WAA=20
    overlapping fgen which may result in CSI/CI (and possible=20
    thundersnow). The intense WAA in the 850-700mb will drive a warm=20
    nose above 0C as far north as coastal CT/RI/Cape Cod, so some=20
    transition to sleet is likely, but otherwise a very cold airmass=20
    will allow SLRs to be above climo (but dropping during the event)=20
    which will help that efficient snow growth. The DGZ is quite=20
    elevated, so the best ascent will not cross-hatch into the snow=20
    growth region in most areas, but nevertheless, robust moisture on=20
    IVT exceeding the 90th percentile will wring out to this heavy=20
    snow, and it is possible some 48-hr total snowfall will reach more=20
    than 2 feet in parts of New England, with widespread 6-12" covering
    most of the Mid-Atlantic, Ohio Valley, and rest of the Northeast=20
    before this event winds down.

    Although most of the accumulation will occur by 12Z Monday, the
    aforementioned inverted trough linking back to the upper low may
    allow for wrap-around snowfall to linger much of Monday and into
    Monday night adding a few more inches of cold fluffy snow to the
    area, especially New England and Upstate NY. WSSI-P indicates
    continues high probabilities (>80%) for major impacts, and the I-95
    corridor between NYC and Portland, ME will be treacherous through
    Monday.

    Farther south, freezing rain will continue for parts of the Mid-
    Atlantic, especially northern NC, southeast VA, and potentially
    along the I-95 corridor as far north as NYC. While additional
    freezing rain amounts are expected to be modest as precip begins to
    wind down (WPC probabilities suggest a 50-70% chance of at least
    0.1" of ice), this will be on top of prior icing to enhance impacts
    including treacherous travel and power outages. With extremely cold temperatures likely after this storm persisting for many days, any
    power outages will become a life-threatening situation for parts of
    the Mid-Atlantic states.


    ...Great Lakes...
    Days 1-3...

    Broad cyclonic flow will persist across the east, and multiple
    embedded shortwaves will ride through this trough out of Canada,
    each one acting to reinforce cold advection (CAA) across the Great
    Lakes to support rounds of lake effect snow (LES). While GLERL
    indicates that water temperatures are cooling, Lake Erie is
    entirely ice covered, and with the very cold temperatures this week
    continuing, additional ice cover is expected. However, there
    should still be sufficient instability and moisture to support LES
    each day through the forecast period. LES is not expected to be
    extremely intense, although will be efficient downstream of Lake
    Ontario towards the Tug Hill Plateau at times, and it is this area
    that is expected to receive the heaviest LES. WPC probabilities for
    all 3 days indicate a high chance (>70%) for at least 8 inches east
    of Lake Ontario, with lower probabilities for 8+ inches (10-30%
    chance) southeast of Lake Michigan and across the eastern U.P. on
    the south shore of Lake Superior.

    Weiss



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5X0xN7MdHtpiv0Oq5XxTtzmHSf-mjyyl5Z8e4q_9Z6UZb= c44QpuSi4xTywscDvjJby3zed3keoBg7ZLpxNDxroebvd4$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!5X0xN7MdHtpiv0Oq5XxTtzmHSf-mjyyl5Z8e4q_9Z6UZb= c44QpuSi4xTywscDvjJby3zed3keoBg7ZLpxNDxHkG_Cm8$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, January 26, 2026 07:07:50
    FOUS11 KWBC 260707
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    207 AM EST Mon Jan 26 2026

    Valid 12Z Mon Jan 26 2026 - 12Z Thu Jan 29 2026


    ...New England...
    Day 1...

    The major winter storm that swept over the Nation the last few
    days will continue to gradually exit the Northeast today, with
    lingering additional snowfall across parts of New England. By the
    start of the forecast period (12z Mon), the primary surface low
    will be sliding east into the open Atlantic and only provide for
    some favorable ocean-enhanced snow from the south coast of ME to
    eastern MA. Otherwise, mostly light to moderate snow will be
    associated with a weakening 850mb low tracking across northern New
    England. Additional snowfall amounts through tonight are expected
    to range from 3-5", with the highest probabilities (50-80%) for
    greater than 4" extending from the northern coast of MA to eastern
    ME. Storm total snowfall amounts from Sunday through the D1 period
    are expected to exceed 20" across parts of New England.


    ...Great Lakes...
    Days 1-3...

    Broad cyclonic flow will persist across the east, and multiple
    embedded shortwaves will ride through this trough out of Canada,
    each one acting to reinforce cold advection (CAA) across the Great
    Lakes to support rounds of lake effect snow (LES). While GLERL
    indicates that water temperatures are cooling, Lake Erie is
    entirely ice covered, and with the very cold temperatures this week
    continuing, additional ice cover is expected. However, there
    should still be sufficient instability and moisture to support LES
    each day through the forecast period. LES is not expected to be
    extremely intense, although will be efficient downstream of Lake
    Ontario towards the Tug Hill Plateau at times, and it is this area
    that is expected to receive the heaviest LES. WPC probabilities for
    all 3 days indicate a high chance (>80%) for at least 12 inches
    east of Lake Ontario, with lower probabilities for 8+ inches
    (30-60% chance) east of Lake Michigan and across the eastern U.P.
    on the south shore of Lake Superior.


    Snell



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, January 26, 2026 20:22:50
    FOUS11 KWBC 262022
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    322 PM EST Mon Jan 26 2026

    Valid 00Z Tue Jan 27 2026 - 00Z Fri Jan 30 2026


    ...New England...
    Day 1...

    The final bands of the major winter storm shift east from New
    England this evening. A couple additional inches are possible after
    00Z over much of Maine down through the Mass coast.


    ...Great Lakes...
    Days 1-3...

    Broad cyclonic flow and trough passages persist across the Great
    Lakes as low pressure over Hudson Bay shifts south over Ontario
    through Thursday. These will produce rounds of lake effect snow=20
    (LES) particularly starting Tuesday behind a notable upper trough
    passage. According to GLERL, Lake Erie is essentially ice=20
    covered, so available moisture will be limited there while Lakes=20
    Superior and Ontario remain largely. Westerly flow allows Day 2/3=20
    PWPF for >6" are over 50% in the Tug Hill and just Day 2 for the
    eastern U.P. of Michigan.


    ...Cascades...
    Days 2/3...

    The next trough axis shunts the powerful ridge east Tuesday night
    with precip over the WA Cascades then through Thursday. Snow levels
    rise from 4000 to 5000ft over the WA Cascades Wednesday through
    Thursday. PWPF for >6" is 40-70% above the snow level (above pass
    level) by Thursday.


    The probability for significant icing is less than 10 percent.



    Jackson




    ...Extreme Cold Key Messages are linked below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!-0TZxpay_jM8Z4Q34rmMmud52o6t8jkHOE9b3VqfOemR-= ZzRDBrxLmQXLRJn74txeFUITeYsrY6M3nwWigr62iJQsj4$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, January 27, 2026 07:33:44
    FOUS11 KWBC 270733
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    233 AM EST Tue Jan 27 2026

    Valid 12Z Tue Jan 27 2026 - 12Z Fri Jan 30 2026


    ...Great Lakes...
    Days 1-3...

    Broad cyclonic flow and trough passages persist across the Great
    Lakes as low pressure over Hudson Bay shifts south over Ontario
    through Thursday. These will produce rounds of lake effect snow=20
    (LES) beginning today behind a notable upper trough passage. 850mb
    temperatures will remain quite cold during this period, with
    temperatures around -18 to -24C, and below the 10th climatological
    percentile. According to GLERL, Lake Erie is essentially ice=20
    covered, so available moisture will be limited there while Lakes=20
    Superior and Ontario remain largely open. Westerly flow will
    continue across the Lower Great Lakes through Thursday night, with
    northerly flow more likely on Day 3 across the Upper Great Lakes,
    This allows Days 1-3 PWPF for >8" over 50% in the Tug Hill and for
    the eastern U.P. of Michigan. The heaviest snowfall is no doubt
    most likely downwind of Lake Ontario and the Tug Hill, where 50-60% probabilities for >18" reach the shoreline of Oswego county.


    ...Cascades...
    Days 2/3...

    The next trough axis to near the Pacific Northwest shunts the=20
    powerful western ridge eastward Tuesday night, with precip over=20
    the WA Cascades then through Thursday. Snow levels rise from 4000=20
    to 5000ft over the WA Cascades Wednesday through Thursday. PWPF for
    6" is 40-70% above the snow level (above pass level) by Thursday.


    The probability for significant icing is less than 10 percent.



    Snell





    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!8NunqgJMY9ONsq94cDZxgfNTy_qFZpb-PYrxM2rTB5EIS= h2M4WxUege40SO-B-z28uH25Ynjwag2vrjv-7YR7oHbKF4$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, January 27, 2026 19:31:26
    FOUS11 KWBC 271931
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    231 PM EST Tue Jan 27 2026

    Valid 00Z Wed Jan 28 2026 - 00Z Sat Jan 31 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is essentially ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue through Wednesday before the approach
    of a sharp 500mb shortwave pivots through and shifts winds more out
    of the N-NNW by Thursday. Northerly flow continues Friday as high
    pressure builds in over the Northern Plains. 72-hour WPC
    probabilities depict high chances (>70%) for snowfall totals >4"
    over the northern tier of the Michigan U.P. and down wind of Lake=20
    Ontario to the south of an over the Tug Hill. The area with the=20
    best odds of seeing over a foot of snow over the next few days are=20
    near the Oswego, NY area where WPC probabilities for over a foot of
    snow are in the moderate range of probabilities (40-60%).=20


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is high (>70%) around Stevens
    Pass, but lighter accumulations around Snoqualmie are anticipated
    at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 2-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Snow is not
    expected to be overly heavy, although the Black Hills through
    orographic lifting may be able to see snowfall amounts surpass 6".
    This is supported in WPC probabilities which show moderate-to-high
    chances (50-70%) for >4" of snow in the Black Hills, and low
    chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
    on south and east through the Missouri River Valley, most snowfall accumulations are likely to range between 1-3". Some hazardous
    travel is possible, especially where roads temperatures are at or
    below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 3-3.5...

    ...Confidence In Impactful Snowfall Increasing For the Southern=20
    Appalachians and Southern Mid-Atlantic...

    To say there remains a large amount of model spread in the
    potential winter storm beyond Day 3 would be an understatement. In
    the past 24 hours, ensemble guidance have flipped camps to where
    the GEFS are the snowier members, CMCE are more in the middle, and
    the EC-EPS are trending less snowy. It is worth noting that AI=20
    ensemble membership are not as snowy as the GEFS, but show a little
    more snow than the EC-EPS, making this an interesting test in how=20
    the AI ensemble membership performs.=20

    Regarding the setup-- WPC Cluster Analysis shows this potential=20
    winter storm comes down to several factors: 1) strength of the=20
    emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
    trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
    east. 4) Confluence strength near Nova Scotia. They all work=20
    together in an intricate dance that makes for difficulties in=20
    modeling. A stronger/slower shortwave can buy time for confluence=20
    over New England and Nova Scotia to weaken, giving the shortwave=20
    more time to amplify, and allow for closer storm tracks to the=20
    coast that bring heavy snow as far west as the I-95 corridor (some=20
    GEFS members and some CMCE members). Where the shortwave is=20
    stronger but progressive, heavier snowfall occurs but largely=20
    closer to the coast and as far west as the NC Piedmont (CMCE=20
    members, UK ensembles, split EC/GEFS members). If the shortwave=20
    trough is more progressive and cannot separate itself from the=20
    larger TPV to the east there is less amplification, it results in=20
    a flatter and more positively/tilted shortwave trough, and thus the=20
    storm remains largely out at sea (EPS, EC-AIFS ensembles, some=20
    GEFS/CMCE members). It is worth noting that, while the EC-AIFS has=20
    largely performed well inside of 5 days much of the winter season,=20
    the EC-AIFS and ECMWF did suppress the track of the most recent=20
    winter storm too much ~4-5 days out before correcting northward=20
    inside of 72 hours out.

    This setup is highly timing dependent; from the primary shortwave
    trough currently east of Hudson Bay, to the interaction/spacing of
    the 500mb cyclonic gyres in southeast Canada and south of Iceland
    that promote the confluence ahead of the potential storm, to the=20
    incoming Pacific shortwaves that track into western Canada and
    adjust the strength/position of the western North America ridge.=20
    There remain a host of embedded shortwaves that will work together=20
    to create a complex storm evolution off the East Coast. Whatever=20
    the current model solutions show beyond 72 hours out is unlikely to
    be the final product. Expect additional model changes in the=20
    coming days. If there is one thing that has increased in confidence
    in the past 24 hours, it is the opportunity for coastal flooding=20
    and beach erosion along the Mid-Atlantic coast. Please refer to our
    "What We know, What We Don't Know" social media post for=20
    additional information.

    The one thing they do agree on is this upper trough tracks through
    the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
    mean layer moisture to support snow from central KY to the southern Appalachians through Friday evening. WPC probabilities do
    show increasing chances for at least minor accumulations >2" over
    KY and northeast TN, while there are low-chances (10-30%) for
    snowfall totals >4" through early Saturday morning in the TN/NC Smokeys
    and Blue Ridge of NC. Residents and those traveling to the=20
    Carolinas on north up the East Coast will want to continue=20
    following the forecasts from WPC and your local NWS WFO for the=20
    latest regarding this potential winter storm.=20


    The probability for significant icing is less than 10 percent.


    Mullinax




    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!6VI14otitwAAstNrC60qAGwJSrOE6Zf0oLu0MtZRucHys= 6sfDSsnz6A0nRg5hdjsoJ-6sT4HYazaHiiRfGLVWtSFuMg$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, January 27, 2026 20:09:29
    FOUS11 KWBC 272009
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    309 PM EST Tue Jan 27 2026

    Valid 00Z Wed Jan 28 2026 - 00Z Sat Jan 31 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is essentially ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue through Wednesday before the approach
    of a sharp 500mb shortwave pivots through and shifts winds more out
    of the N-NNW by Thursday. Northerly flow continues Friday as high
    pressure builds in over the Northern Plains. 72-hour WPC
    probabilities depict high chances (>70%) for snowfall totals >4"
    over the northern tier of the Michigan U.P. and down wind of Lake=20
    Ontario to the south of an over the Tug Hill. The area with the=20
    best odds of seeing over a foot of snow over the next few days are=20
    near the Oswego, NY area where WPC probabilities for over a foot of
    snow are in the moderate range of probabilities (40-60%).=20


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is high (>70%) around Stevens
    Pass, but lighter accumulations around Snoqualmie are anticipated
    at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 2-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Snow is not
    expected to be overly heavy, although the Black Hills through
    orographic lifting may be able to see snowfall amounts surpass 6".
    This is supported in WPC probabilities which show moderate-to-high
    chances (50-70%) for >4" of snow in the Black Hills, and low
    chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
    on south and east through the Missouri River Valley, most snowfall accumulations are likely to range between 1-3". Some hazardous
    travel is possible, especially where roads temperatures are at or
    below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 3-3.5...

    ...Confidence In Impactful Snowfall Increasing For the Southern=20
    Appalachians and Southern Mid-Atlantic...

    To say there remains a large amount of model spread in the
    potential winter storm beyond Day 3 would be an understatement. In
    the past 24 hours, ensemble guidance have flipped camps to where
    the GEFS are the snowier members, CMCE are more in the middle, and
    the EC-EPS are trending less snowy. It is worth noting that AI=20
    ensemble membership are not as snowy as the GEFS, but show a little
    more snow than the EC-EPS, making this an interesting test in how=20
    the AI ensemble membership performs.=20

    Regarding the setup-- WPC Cluster Analysis shows this potential=20
    winter storm comes down to several factors: 1) strength of the=20
    emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
    trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
    east. 4) Confluence strength near Nova Scotia. They all work=20
    together in an intricate dance that makes for difficulties in=20
    modeling. A stronger/slower shortwave can buy time for confluence=20
    over New England and Nova Scotia to weaken, giving the shortwave=20
    more time to amplify, and allow for closer storm tracks to the=20
    coast that bring heavy snow as far west as the I-95 corridor (some=20
    GEFS members and some CMCE members). Where the shortwave is=20
    stronger but progressive, heavier snowfall occurs but largely=20
    closer to the coast and as far west as the NC Piedmont (CMCE=20
    members, UK ensembles, split EC/GEFS members). If the shortwave=20
    trough is more progressive and cannot separate itself from the=20
    larger TPV to the east there is less amplification, it results in=20
    a flatter and more positively/tilted shortwave trough, and thus the storm remains largely out at sea (EPS, EC-AIFS ensembles, some GEFS/CMCE
    members). It is worth noting that, while the EC-AIFS has largely=20
    performed well inside of 5 days much of the winter season, the EC-=20
    AIFS and ECMWF did suppress the track of the most recent winter=20
    storm too much ~4-5 days out before correcting northward inside of=20
    72 hours out.

    This setup is highly timing dependent; from the primary shortwave
    trough currently east of Hudson Bay, to the interaction/spacing of
    the 500mb cyclonic gyres in southeast Canada and south of Iceland
    that promote the confluence ahead of the potential storm, to the=20
    incoming Pacific shortwaves that track into western Canada and
    adjust the strength/position of the western North America ridge.=20
    There remain a host of embedded shortwaves that will work together=20
    to create a complex storm evolution off the East Coast. Whatever=20
    the current model solutions show beyond 72 hours out is unlikely to
    be the final product. Expect additional model changes in the=20
    coming days. If there is one thing that has increased in confidence
    in the past 24 hours, it is the opportunity for coastal flooding=20
    and beach erosion along the Mid-Atlantic coast. Please refer to our
    "What We know, What We Don't Know" social media post for=20
    additional information.

    The one thing they do agree on is this upper trough tracks through
    the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
    mean layer moisture to support snow from central KY to the southern Appalachians through Friday evening. WPC probabilities do
    show increasing chances for at least minor accumulations >2" over
    KY and northeast TN, while there are low-chances (10-30%) for
    snowfall totals >4" through early Saturday morning in the TN/NC
    Smokeys and Blue Ridge of NC. Residents and those traveling to the
    Carolinas on north up the East Coast will want to continue=20
    following the forecasts from WPC and your local NWS WFO for the=20
    latest regarding this potential winter storm.=20


    The probability for significant icing is less than 10 percent.


    Mullinax





    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!54SB-pOI55Au96P5L94fHwqMmZ5LkWpzYAasipw8QCoDB= HpKat7rnUR9CGCuvaNDYBiVEtFlpNZAFxNTxzAKGVc0XKY$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, January 27, 2026 20:12:57
    FOUS11 KWBC 272012
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    312 PM EST Tue Jan 27 2026

    Valid 00Z Wed Jan 28 2026 - 00Z Sat Jan 31 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is essentially ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue through Wednesday before the approach
    of a sharp 500mb shortwave pivots through and shifts winds more out
    of the N-NNW by Thursday. Northerly flow continues Friday as high
    pressure builds in over the Northern Plains. 72-hour WPC
    probabilities depict high chances (>70%) for snowfall totals >4"
    over the northern tier of the Michigan U.P. and down wind of Lake=20
    Ontario to the south of an over the Tug Hill. The area with the=20
    best odds of seeing over a foot of snow over the next few days are=20
    near the Oswego, NY area where WPC probabilities for over a foot of
    snow are in the moderate range of probabilities (40-60%).=20


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is high (>70%) around Stevens
    Pass, but lighter accumulations around Snoqualmie are anticipated
    at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 2-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Snow is not
    expected to be overly heavy, although the Black Hills through
    orographic lifting may be able to see snowfall amounts surpass 6".
    This is supported in WPC probabilities which show moderate-to-high
    chances (50-70%) for >4" of snow in the Black Hills, and low
    chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
    on south and east through the Missouri River Valley, most snowfall accumulations are likely to range between 1-3". Some hazardous
    travel is possible, especially where roads temperatures are at or
    below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 3-3.5...

    ...Confidence In Impactful Snowfall Increasing For the Southern=20
    Appalachians and Southern Mid-Atlantic...

    To say there remains a large amount of model spread in the
    potential winter storm beyond Day 3 would be an understatement. In
    the past 24 hours, ensemble guidance have flipped camps to where
    the GEFS are the snowier members, CMCE are more in the middle, and
    the EC-EPS are trending less snowy. It is worth noting that AI=20
    ensemble membership are not as snowy as the GEFS, but show a little
    more snow than the EC-EPS, making this an interesting test in how=20
    the AI ensemble membership performs.=20

    Regarding the setup-- WPC Cluster Analysis shows this potential=20
    winter storm comes down to several factors: 1) strength of the=20
    emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
    trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
    east. 4) Confluence strength near Nova Scotia. They all work=20
    together in an intricate dance that makes for difficulties in=20
    modeling. A stronger/slower shortwave can buy time for confluence=20
    over New England and Nova Scotia to weaken, giving the shortwave=20
    more time to amplify, and allow for closer storm tracks to the=20
    coast that bring heavy snow as far west as the I-95 corridor (some=20
    GEFS members and some CMCE members). Where the shortwave is=20
    stronger but progressive, heavier snowfall occurs but largely=20
    closer to the coast and as far west as the NC Piedmont (CMCE=20
    members, UK ensembles, split EC/GEFS members). If the shortwave=20
    trough is more progressive and cannot separate itself from the=20
    larger TPV to the east there is less amplification, it results in=20
    a flatter and more positively/tilted shortwave trough, and thus the
    storm remains largely out at sea (EPS, EC-AIFS ensembles, some=20
    GEFS/CMCE members). It is worth noting that, while the EC-AIFS has=20
    largely performed well inside of 5 days much of the winter season,=20
    the EC- AIFS and ECMWF did suppress the track of the most recent=20
    winter storm too much ~4-5 days out before correcting northward=20
    inside of 72 hours out.

    This setup is highly timing dependent; from the primary shortwave
    trough currently east of Hudson Bay, to the interaction/spacing of
    the 500mb cyclonic gyres in southeast Canada and south of Iceland
    that promote the confluence ahead of the potential storm, to the=20
    incoming Pacific shortwaves that track into western Canada and
    adjust the strength/position of the western North America ridge.=20
    There remain a host of embedded shortwaves that will work together=20
    to create a complex storm evolution off the East Coast. Whatever=20
    the current model solutions show beyond 72 hours out is unlikely to
    be the final product. Expect additional model changes in the=20
    coming days. If there is one thing that has increased in confidence
    in the past 24 hours, it is the opportunity for coastal flooding=20
    and beach erosion along the Mid-Atlantic coast. Please refer to our
    "What We know, What We Don't Know" social media post for=20
    additional information.

    The one thing they do agree on is this upper trough tracks through
    the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
    mean layer moisture to support snow from central KY to the southern Appalachians through Friday evening. WPC probabilities do
    show increasing chances for at least minor accumulations >2" over
    KY and northeast TN, while there are low-chances (10-30%) for
    snowfall totals >4" through early Saturday morning in the TN/NC
    Smokeys and Blue Ridge of NC. Residents and those traveling to the
    Carolinas on north up the East Coast will want to continue=20
    following the forecasts from WPC and your local NWS WFO for the=20
    latest regarding this potential winter storm.=20


    The probability for significant icing is less than 10 percent.


    Mullinax






    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!6n-iHJKs776ZdQQmter1T3bY9tYWwGaL_csVXzv1NZMbv= Z1KeGyQSUWbB1TKYcgb1-m6K7MWiSPxJKNPHtV9eyKYDFI$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, January 28, 2026 08:00:05
    FOUS11 KWBC 280759
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    259 AM EST Wed Jan 28 2026

    Valid 12Z Wed Jan 28 2026 - 12Z Sat Jan 31 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is essentially ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue today before the approach of a sharp
    500mb shortwave pivots through and shifts winds more out of the=20
    N-NNW by Thursday. Northerly flow continues Friday as high pressure
    builds in over the Northern Plains. This northerly flow supports
    the most likely area of heavy snow on Day 3 to be down wind of Lake
    Michigan, potentially into the Chicago metro. 72-hour WPC=20
    probabilities depict high chances (>70%) for snowfall totals >8"=20
    over the eastern shores of Lake Superior in the Michigan U.P. and=20
    down wind of Lake Ontario to the south of an over the Tug Hill. The
    area with the best odds of seeing over a foot of additional snow=20
    (most on Day 1) over the next few days are near the Oswego, NY area
    where WPC probabilities for over a foot of snow are 10-20%. Day 3
    probabilities down wind of Lake Michigan current depict moderate
    probabilities 40-50% for at least 4" across the southwest shores of
    Lake Michigan.


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is moderate (40-70%) around=20
    Stevens Pass, but lighter accumulations around Snoqualmie are=20
    anticipated at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 2-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Snow is not
    expected to be overly heavy, although the Black Hills through
    orographic lifting may be able to see snowfall amounts surpass 6".
    This is supported in WPC probabilities which show moderate-to-high
    chances (50-70%) for >4" of snow in the Black Hills, and low
    chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
    on south and east through the Missouri River Valley, most snowfall accumulations are likely to range between 1-3". Some hazardous
    travel is possible, especially where roads temperatures are at or
    below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 3...

    ...Confidence In Impactful Snowfall Increasing For the Southern=20
    Appalachians and Southern Mid-Atlantic; Key Messages are linked at
    the bottom of the discussion...

    To say there remains a large amount of model spread in the
    potential winter storm beyond Day 3 would be an understatement. In
    the past 36-24 hours, ensemble guidance have flipped camps to=20
    where the GEFS are the snowier members, CMCE are more in the=20
    middle, and the EC-EPS are less snowy. It is worth noting that AI=20
    ensemble membership are not as snowy as the GEFS, but show a little
    more snow than the EC-EPS, making this an interesting test in how=20
    the AI ensemble membership performs. However, within this overall
    "cloud" of uncertainty, guidance is beginning to hone in on higher
    chances for impactful snowfall across the Carolinas and southern
    Virginia by the end of the Day 3 timeframe.

    Regarding the setup-- WPC Cluster Analysis shows this potential=20
    winter storm comes down to several factors: 1) strength of the=20
    emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
    trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
    east. 4) Confluence strength near Nova Scotia. They all work=20
    together in an intricate dance that makes for difficulties in=20
    modeling. A stronger/slower shortwave can buy time for confluence=20
    over New England and Nova Scotia to weaken, giving the shortwave=20
    more time to amplify, and allow for closer storm tracks to the=20
    coast that bring heavy snow as far west as the I-95 corridor (some=20
    GEFS members and some CMCE members). Where the shortwave is=20
    stronger but progressive, heavier snowfall occurs but largely=20
    closer to the coast and as far west as the NC Piedmont (CMCE=20
    members, UK ensembles, split EC/GEFS members). If the shortwave=20
    trough is more progressive and cannot separate itself from the=20
    larger TPV to the east there is less amplification, it results in=20
    a flatter and more positively/tilted shortwave trough, and thus the
    storm remains largely out at sea (EPS, EC-AIFS ensembles, some=20
    GEFS/CMCE members). It is worth noting that, while the EC-AIFS has=20
    largely performed well inside of 5 days much of the winter season,=20
    the EC- AIFS and ECMWF did suppress the track of the most recent=20
    winter storm too much ~4-5 days out before correcting northward=20
    inside of 72 hours out.

    In terms of storm analogs, this upper level setup and TPV=20
    interaction does not appear like a common scenario to get a deep=20
    upper low rapidly deepening near the Southeast/Mid- Atlantic. Most=20
    analog matches seem to get towards the closed upper low in=20
    different ways or suppress the system altogether leaving little in=20
    terms of precipitation. However, the 12z Tuesday CIPS Analogs
    (GFS-based) highlighted the significant winter storm of March 1980
    as an interesting top match. This storm produced very heavy=20
    snowfall across VA and eastern NC and can simply show the ceiling=20
    this type of setup can have. Like what was previously mentioned,=20
    other limited analogs are suppressed and show the very low floor=20
    that is still possible. All ensemble systems GEFS/CMCE/EPS/EC-
    AIFS/AIGEFS show this large spread as well.

    Back to the current forecast. This setup is highly timing=20
    dependent; from the primary shortwave trough currently east of=20
    Hudson Bay, to the interaction/spacing of the 500mb cyclonic gyres=20
    in southeast Canada and south of Iceland that promote the=20
    confluence ahead of the potential storm, to the incoming Pacific=20
    shortwaves that track into western Canada and adjust the=20
    strength/position of the western North America ridge. There remain=20
    a host of embedded shortwaves that will work together to create a=20
    complex storm evolution off the East Coast. Whatever the current=20
    model solutions show beyond 72 hours out is unlikely to be the=20
    final product. Expect additional model changes in the coming days.=20
    If there is an additional aspect to this storm that has increased=20
    in confidence in the past 24 hours, it is the opportunity for=20
    coastal flooding and beach erosion along the Mid-Atlantic coast.

    The one thing they do agree on is this upper trough tracks through
    the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
    mean layer moisture to support snow from central KY to the southern Appalachians through Friday night. Then, the closing off of a 850mb
    low seems plausible across the southern Appalachians Saturday=20
    morning, which should help increase lift into the Carolina=20
    Piedmont. WPC probabilities do show increasing chances for at least
    minor accumulations >4" over eastern KY and northeast TN, while=20
    there are low- chances (10-30%) for snowfall totals >4" through=20
    early Saturday morning in the TN/NC Smokeys and Blue Ridge of NC.=20 Probabilities then begin to increase to 30-50% across central NC by
    12z Saturday. Most snowfall associated with this system is=20
    expected to occur after 12z Saturday, so be sure to check back for=20
    the latest forecast as it enters the short range over the next few=20
    days. Residents and those traveling to the Carolinas on north up=20
    the East Coast will want to continue following the forecasts from=20
    WPC and your local NWS WFO for the latest regarding this potential=20
    winter storm.



    The probability for significant icing is less than 10 percent.


    Snell/Mullinax





    ...Extreme Cold (1) & Winter Storm (2) Key Messages are in effect.
    Please see current Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!77Xu4C4_ejyNPuXJ8gEnnObVKlTXBwG2suWpfLuKOVzPG= BINbP5K5P9TIQ5cCqP2wLS3M1N8_NCpSzZOgD1PInZ4pUQ$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!77Xu4C4_ejyNPuXJ8gEnnObVKlTXBwG2suWpfLuKOVzPG= BINbP5K5P9TIQ5cCqP2wLS3M1N8_NCpSzZOgD1PtfsLqMU$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, January 28, 2026 08:07:45
    FOUS11 KWBC 280807
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    307 AM EST Wed Jan 28 2026

    Valid 12Z Wed Jan 28 2026 - 12Z Sat Jan 31 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is essentially ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue today before the approach of a sharp
    500mb shortwave pivots through and shifts winds more out of the=20
    N-NNW by Thursday. Northerly flow continues Friday as high pressure
    builds in over the Northern Plains. This northerly flow supports
    the most likely area of heavy snow on Day 3 to be down wind of Lake
    Michigan, potentially into the Chicago metro. 72-hour WPC=20
    probabilities depict high chances (>70%) for snowfall totals >8"=20
    over the eastern shores of Lake Superior in the Michigan U.P. and=20
    down wind of Lake Ontario to the south of an over the Tug Hill. The
    area with the best odds of seeing over a foot of additional snow=20
    (most on Day 1) over the next few days are near the Oswego, NY area
    where WPC probabilities for over a foot of snow are 10-20%. Day 3
    probabilities down wind of Lake Michigan current depict moderate
    probabilities 40-50% for at least 4" across the southwest shores of
    Lake Michigan.


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is moderate (40-70%) around=20
    Stevens Pass, but lighter accumulations around Snoqualmie are=20
    anticipated at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 2-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Snow is not
    expected to be overly heavy, although the Black Hills through
    orographic lifting may be able to see snowfall amounts surpass 6".
    This is supported in WPC probabilities which show moderate-to-high
    chances (50-70%) for >4" of snow in the Black Hills, and low
    chances (10-30%) in their peaks for >8". Elsewhere, from eastern MT
    on south and east through the Missouri River Valley, most snowfall accumulations are likely to range between 1-3". Some hazardous
    travel is possible, especially where roads temperatures are at or
    below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 3...

    ...Confidence In Impactful Snowfall Increasing For the Southern=20
    Appalachians and Southern Mid-Atlantic; Key Messages are linked at
    the bottom of the discussion...

    To say there remains a large amount of model spread in the
    potential winter storm beyond Day 3 would be an understatement. In
    the past 36-24 hours, ensemble guidance have flipped camps to=20
    where the GEFS are the snowier members, CMCE are more in the=20
    middle, and the EC-EPS are less snowy. It is worth noting that AI=20
    ensemble membership are not as snowy as the GEFS, but show a little
    more snow than the EC-EPS, making this an interesting test in how=20
    the AI ensemble membership performs. However, within this overall
    "cloud" of uncertainty, guidance is beginning to hone in on higher
    chances for impactful snowfall across the Carolinas and southern
    Virginia by the end of the Day 3 timeframe.

    Regarding the setup-- WPC Cluster Analysis shows this potential=20
    winter storm comes down to several factors: 1) strength of the=20
    emerging Great Lakes shortwave trough. 2) speed of the shortwave=20
    trough. 3) tilt/amplitude of the shortwave trough as it tracks=20
    east. 4) Confluence strength near Nova Scotia. They all work=20
    together in an intricate dance that makes for difficulties in=20
    modeling. A stronger/slower shortwave can buy time for confluence=20
    over New England and Nova Scotia to weaken, giving the shortwave=20
    more time to amplify, and allow for closer storm tracks to the=20
    coast that bring heavy snow as far west as the I-95 corridor (some=20
    GEFS members and some CMCE members). Where the shortwave is=20
    stronger but progressive, heavier snowfall occurs but largely=20
    closer to the coast and as far west as the NC Piedmont (CMCE=20
    members, UK ensembles, split EC/GEFS members). If the shortwave=20
    trough is more progressive and cannot separate itself from the=20
    larger TPV to the east there is less amplification, it results in=20
    a flatter and more positively/tilted shortwave trough, and thus the
    storm remains largely out at sea (EPS, EC-AIFS ensembles, some=20
    GEFS/CMCE members). It is worth noting that, while the EC-AIFS has=20
    largely performed well inside of 5 days much of the winter season,=20
    the EC- AIFS and ECMWF did suppress the track of the most recent=20
    winter storm too much ~4-5 days out before correcting northward=20
    inside of 72 hours out.

    In terms of storm analogs, this upper level setup and TPV=20
    interaction does not appear like a common scenario to get a deep=20
    upper low rapidly strengthening near the Southeast/Mid- Atlantic.=20
    Most analog matches seem to get towards the closed upper low in=20
    different ways or suppress the system altogether leaving little in=20
    terms of precipitation. However, the 12z Tuesday CIPS Analogs (GFS-
    based) highlighted the significant winter storm of March 1980 as=20
    an interesting top match. This storm produced very heavy snowfall=20
    across VA and eastern NC and can simply show the ceiling this type=20
    of setup can have. Like what was previously mentioned, other=20
    limited analogs are suppressed and show the very low floor that is=20
    still possible. All ensemble systems GEFS/CMCE/EPS/EC- AIFS/AIGEFS=20
    show this large spread as well.

    Back to the current forecast. This setup is highly timing=20
    dependent; from the primary shortwave trough currently east of=20
    Hudson Bay, to the interaction/spacing of the 500mb cyclonic gyres=20
    in southeast Canada and south of Iceland that promote the=20
    confluence ahead of the potential storm, to the incoming Pacific=20
    shortwaves that track into western Canada and adjust the=20
    strength/position of the western North America ridge. There remain=20
    a host of embedded shortwaves that will work together to create a=20
    complex storm evolution off the East Coast. Whatever the current=20
    model solutions show beyond 72 hours out is unlikely to be the=20
    final product. Expect additional model changes in the coming days.=20
    If there is an additional aspect to this storm that has increased=20
    in confidence in the past 24 hours, it is the opportunity for=20
    coastal flooding and beach erosion along the Mid-Atlantic coast.

    The one thing they do agree on is this upper trough tracks through
    the OH Valley Friday afternoon with sufficient PVA and 850-500mb=20
    mean layer moisture to support snow from central KY to the southern Appalachians through Friday night. Then, the closing off of a 850mb
    low seems plausible across the southern Appalachians Saturday=20
    morning, which should help increase lift into the Carolina=20
    Piedmont. WPC probabilities do show increasing chances for at least
    minor accumulations >4" over eastern KY and northeast TN, while=20
    there are low- chances (10-30%) for snowfall totals >4" through=20
    early Saturday morning in the TN/NC Smokeys and Blue Ridge of NC.=20 Probabilities then begin to increase to 30-50% across central NC by
    12z Saturday. Most snowfall associated with this system is=20
    expected to occur after 12z Saturday, so be sure to check back for=20
    the latest forecast as it enters the short range over the next few=20
    days. Residents and those traveling to the Carolinas on north up=20
    the East Coast will want to continue following the forecasts from=20
    WPC and your local NWS WFO for the latest regarding this potential=20
    winter storm.



    The probability for significant icing is less than 10 percent.


    Snell/Mullinax





    ...Extreme Cold (1) & Winter Storm (2) Key Messages are in effect.
    Please see current Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!8TANDUoTZL_uMahppCEn7lOgTUVSMGtUDbz_RXsEfHhME= ATsMx_veotJcy8MV2KCSOFvGpr4l7xjG6CeUg9vKvyvDL8$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!8TANDUoTZL_uMahppCEn7lOgTUVSMGtUDbz_RXsEfHhME= ATsMx_veotJcy8MV2KCSOFvGpr4l7xjG6CeUg9vTm6w4sc$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, January 28, 2026 19:47:59
    FOUS11 KWBC 281947
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    247 PM EST Wed Jan 28 2026

    Valid 00Z Thu Jan 29 2026 - 00Z Sun Feb 01 2026


    ...Great Lakes...
    Days 1-3...

    The seemingly endless cyclonic flow that has kept the LES machine=20
    cranking over snow belts of the Great Lakes looks to continue
    through the remainder of the work-week. Frigid 850mb temperatures=20
    will persist with temperatures around -18 to -24C, which are below
    the 10th climatological percentile. According to GLERL, Lake Erie=20
    is effectively ice covered, so available moisture will be limited=20
    there while Lakes Superior and Ontario remain largely open. W-NWrly
    low-level winds will continue today before the approach of a sharp
    500mb shortwave passes through and shifts winds more out of the=20
    north by late Thursday. Northerly flow continues Friday with=20
    shifting NNE flow possible into Saturday, which could place the=20
    Chicagoland area under the presence of a Lake Michigan single-=20
    banded LES streamer late Friday into Saturday. 72-hour WPC=20
    probabilities depict high chances (>70%) for snowfall totals >8"=20
    over the eastern shores of Lake Superior in the Michigan U.P. and=20
    down wind of Lake Ontario to the south of an over the Tug Hill. The
    area with the best odds of seeing over a foot of additional snow=20
    (most on Day 1) over the next few days are near the Oswego, NY area
    where WPC probabilities for over a foot of snow are 10-20%. Day 3=20 probabilities down wind of Lake Michigan current depict moderate-=20
    to-high chances (40-70%) for at least 4" along the southern shores
    of Lake Michigan.


    ...Cascades & Olympics...
    Days 1-3...

    A series of storm systems tracking into the Gulf of Alaska will
    direct rounds of moisture and WAA at western WA through the
    remainder of the week. Strong upslope flow should support locally
    heavy snowfall totals as low as 4,000ft, but most heavy snow will=20
    reside in the more remote areas above 5,000ft. Snow levels rise=20
    from 4000 to 5000ft over the WA Cascades Wednesday through=20
    Thursday. By Friday, snow levels approach 6,000ft by Friday in
    western WA. WPC probabilities for >4" is moderate (40-60%) around=20
    Stevens Pass, but lighter accumulations around Snoqualmie are=20
    anticipated at this moment given the higher snow levels.

    ...Northern & Central Plains...
    Days 1-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a
    nearby 850mb front to support periods of snow from the northern
    High Plains on south in the the central High Plains. Guidance is
    even keying in on an area of 700mb FGEN over the Black Hills on
    south into the Nebraska Sand Hills that could support moderate snow
    bands Friday morning. Snow is not expected to be overly heavy,=20
    although the Black Hills through orographic lifting and some=20
    localized banding may be able to see snowfall amounts surpass 6".=20
    This is supported in WPC probabilities which show moderate-to-high=20
    chances (50-70%) for >4" of snow in the Black Hills, and low-to-=20
    moderate chances (20-50%) in their peaks for >8". Elsewhere, from=20
    eastern MT on south and east through the Missouri River Valley,=20
    most snowfall accumulations are likely to range between 1-3". Even=20
    some localized instances of freezing rain in the northern High=20
    Plains on late Friday into Saturday given the favorable overrunning
    from WAA at low-mid levels and sub-freezing surface temps. Some=20
    hazardous travel is possible, especially where roads temperatures=20
    are at or below freezing in wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 2.5-3.5...

    ...Confidence growing for a major winter storm & heavy snowfall=20
    across the southern Mid-Atlantic...

    WPC cluster analysis continues to show the primary driving factors
    in the development of this impending winter storm are the
    strength/speed/tilt of the approaching shortwave trough in the
    Great Lakes and the spacing between the trough and the TPV over
    southeast Canada. The meteorology is supportive of a significant
    winter storm from the southern Appalachians and Carolinas on north
    and east through the VA Tidewater. Just about all ensemble=20
    guidance now show the shortwave trough over the OH Valley Friday=20
    evening deepening into a powerful and highly anomalous closed low=20
    that tracks into the southern Appalachians Saturday evening. By the
    end of this forecast period (00Z Sun) the ECMWF 500mb heights are=20 approaching record low levels over the FL Panhandle for late Jan-=20
    early Feb. As the 500mb low approaches, exceptional PVA and WAA=20
    over the Mid-Atlantic coast will spawn low pressure along the=20
    strengthening coastal front. This aligns well across the 12Z GFS=20
    and 06Z ECMWF which show increasing 700mb Q-vector convergence near
    the NC Outer Banks that fosters healthy mid-level ascent. This=20
    aligns favorably beneath the diffluent left-exit region of a=20
    100kt 500mb jet streak located a the base of the closed 500mb low.
    As the 700mb low tracks towards the Cape Fear region Saturday=20
    night, the axis of heaviest snowfall will reside on the 700mb low's
    northern and western flank.

    Where guidance still disagrees is the progression of the storm and
    its proximity to the coast. The tilt of the 500mb trough and closed
    low plays a key role in this, as it maximizes vertical ascent and=20
    draws moisture farther north if the system takes on a negative=20
    tilt. The EC-AIFS ensemble mean has been gradually decreasing QPF=20
    largely because the negative tilt takes longer to occur and there=20
    is less time for the developing 850mb low to tap into moisture off
    the Gulf Stream. Most guidance holds off on a negative until=20
    Sunday, which is why there is a "gap" in the snowfall from northern
    VA on up I-95 to the NYC metro area, but heavy snow becomes=20
    possible over southeast New England by Sunday thanks to the region=20
    sticking out eastward into the Atlantic. Note the 12Z GEFS, 06Z=20
    EPS, and 12Z EC-AIFS ensembles are still showing changes in its=20
    mean inside of 72 hours, so exact amounts and the expanse of the=20
    snow shield are still likely to change. In addition, unlike the=20
    last winter storm, wind will have a more profound impact up and=20
    down the Eastern Seaboard. The 00Z ECMWF EFI shows wind speeds that
    are topping 0.8 from the MA Capes on south along the NC Coast.=20
    These anomalous winds also align with climatologically significant=20
    snowfall potential along the coasts, indicating the concern for=20
    blizzard conditions in affected coastal areas.=20

    CIPS Analogs (GFS-based) continue to suggest this storm's=20
    potential ceiling could be exceptional, particularly in the=20
    Carolinas. CIPS is keying in on several past major winter storms=20
    that featured similar 300mb & 500mb evolutions to what the GFS is=20
    showing, just 100-200 miles farther south and east from where those
    events unfolded. While the CIPS analogs are analyzing the GFS, the
    differences in the GFS versus the ECMWF are not all that different
    when it comes to the meteorology involved: powerful closed upper=20
    low, healthy upper-level divergence over a strengthening coastal=20
    front, and tapping into Atlantic moisture revolving around the=20
    closed 700mb low. In summary-- ensembles are beginning to identify
    the floor of this winter storm (disruptive winter storm in the=20
    southern Mid-Atlantic) but based on some of the analogs, there is a
    potentially more significant-ceiling that could be achieved in the
    Carolinas should guidance consolidate on a slower and more intense
    winter storm. Given it is 72 hours out, there remains some caution
    when it comes to expected snowfall totals.

    WPC probabilities through Saturday night currently show moderate-
    to-high chances (50-80%) for snowfall totals >4" from the NC=20
    Piedmont on east to eastern NC and southeast VA. It is worth noting
    some higher end solutions are present with low-to-moderate chances
    (30-50%) for snowfall totals >8" over central NC through 06Z Sunday.
    The Probabilistic Winter Storm Severity Index (WSSI-P) is=20
    depicting >50% chances for Moderate Impacts from the SC/GA border=20
    on north and east to lower DelMarVa Peninsula. The Major Impacts=20
    are >50% in the eastern Charlotte metro, the NC Piedmont right=20
    along NC's I-95 corridor, and into southeast VA. These elevated
    WSSI-P Major probabilities highlight the concern for a highly=20
    impactful winter storm late Saturday and into Sunday for the=20
    southern Mid-Atlantic with more disruptions to travel and=20
    infrastructure anticipated. Residents and those traveling to the=20
    Carolinas on north up the East Coast will want to continue=20
    following the forecasts from WPC and your local NWS WFO for the=20
    latest regarding this potential winter storm.


    The probability for significant icing is less than 10 percent.


    Mullinax




    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5Cj4msK-dv0Kb7_AGDSgu7ZDdEOXNYFYPw2QvpYtmFd6N= CNtmp24XMTtrscfs6fvs4sGCn1UXXix-0GDZBAeT4q-EBM$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!5Cj4msK-dv0Kb7_AGDSgu7ZDdEOXNYFYPw2QvpYtmFd6N= CNtmp24XMTtrscfs6fvs4sGCn1UXXix-0GDZBAeMWJe7mA$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, January 29, 2026 07:46:52
    FOUS11 KWBC 290746
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    246 AM EST Thu Jan 29 2026

    Valid 12Z Thu Jan 29 2026 - 12Z Sun Feb 01 2026


    ...Great Lakes...
    Days 1-2...

    Continued cyclonic flow will continue to favor lake effect snow=20
    across the Great Lakes for another couple of days. Frigid 850mb=20
    temperatures will persist with temperatures around -18 to=20
    -24C, which are below the 10th climatological percentile. WNW flow
    will turn more northerly (or NNE) as the sharp 500mb shortwave
    passes through later today. On Friday, northerly flow continues
    Friday with NNE flow possible into Chicagoland carrying a band
    into the region overnight into Saturday. Most snow winds downs
    late Saturday into early Sunday with a surface high overhead.
    Single band off Lake Ontario will weaken later today but persist
    through Friday.

    For days 1-2, WPC probabilities for at least 6 inches of snow are
    50% over parts of the Michigan U.P. and downwind of Lake Ontario=20
    near Oswego, where over 10 inches is possible. Over Chicago, WPC=20 probabilities for at least 4 inches are not quite 30% but some CAM=20
    guidance shows a farther westward push out of NW Indiana than=20
    others.=20


    ...Cascades & Olympics...
    Days 1-2...

    A series of storm systems tracking into the Gulf of Alaska will=20
    direct rounds of moisture and WAA at western WA through the=20
    remainder of the week. Strong upslope flow should support locally=20
    heavy snowfall totals above 5,000ft. Snow levels approach=20
    6,000-6,500ft by Friday into Saturday in western WA as=20
    precipitation ends.=20


    ...Northern & Central Plains...
    Days 1-3...

    A weak Pacific shortwave trough tracking NW-SE will ride along a=20
    nearby 850mb front to support periods of snow from the northern=20
    High Plains on south in the the central High Plains. Guidance is=20
    even keying in on an area of 700mb FGEN over the Black Hills on=20
    south into the Nebraska Sand Hills that could support moderate snow
    bands Friday morning. Snow is not expected to be overly heavy,=20
    although the Black Hills through orographic lifting and some=20
    localized banding may be able to see snowfall amounts surpass 6".=20
    This is supported in WPC probabilities which show 60-80%=20
    probabilities for >4" of snow in the Black Hills, and low-to-=20
    moderate chances (20-50%) in their peaks for >8". Elsewhere, from=20
    eastern MT on south and east through the Missouri River Valley,=20
    most snowfall accumulations are likely to range between 1-3". Even=20
    some localized instances of freezing rain in the northern High=20
    Plains on late Friday into Saturday given the favorable overrunning
    from WAA at low-mid levels and sub-freezing surface temps. Some=20
    hazardous travel is possible, especially where roads temperatures=20
    are likely below freezing in the wake of the recent extreme cold.


    ...Southern Appalachians & Mid-Atlantic...
    Days 2-3...

    ...Confidence growing for a major winter storm & heavy snowfall=20
    across the southern Mid-Atlantic...

    Models continue to point to an anomalous and impactful event for=20
    the southern Appalachians and especially southern Mid-Atlantic=20
    states this weekend, aided by record cold into the=20
    Southeast/Florida. Though the various models/ensembles have wavered
    in their evolution and track of the system, nearly all show a=20
    powerful ocean storm that will affect the southern Mid-Atlantic as=20 cyclogenesis ensues.=20

    As a very deep 500mb low approaches the region, exceptional PVA=20
    and WAA over the Mid-Atlantic coast will spawn low pressure along=20
    the strengthening coastal front. Increasing 700mb Q-vector=20
    convergence near the NC Outer Banks will foster healthy mid-level=20
    ascent beneath the diffluent left-exit region of a >100kt 500mb jet
    streak located at the base of the closed 500mb low. As the 700mb=20
    low tracks towards the Cape Fear region Saturday night, the axis of
    heaviest snowfall will reside on the 700mb low's northern and=20
    western flank while surface low pressure explosively deepens into=20
    the 970s mb by Sunday morning. Snow will likely fall heavily at=20
    times over eastern NC late Saturday into early Sunday west of the=20
    surface low as the mid-level upper low eventually catches up. In=20
    addition, winds will increase which will create blowing and=20
    drifting snow with possible blizzard conditions. Snow will also=20
    expand northeastward up along the Mid- Atlantic coast into Long=20
    Island and southern/southeastern New England but with a lot of=20
    uncertainty in the expanse of the precipitation shield.

    Through 12Z Sunday, WPC probabilities for at least 8 inches of=20
    snow are >50% over the southern Appalachians, much of central to=20
    eastern NC, as well as southern VA and northeastern SC. Within this
    region, WPC probabilities for at least 12 inches of snow are >40%=20
    over eastern NC. The footprint of impactful snowfall (>2" to the=20
    south) extends into northeastern/eastern GA, through much of SC=20
    (except for the Lowcountry where ptypes/thermals are more=20
    uncertain), and as far north into the DelMarVa and southeastern NJ.


    The Probabilistic Winter Storm Severity Index (WSSI-P) shows >50%=20
    chances for Major impacts from the NC/SC border to southeastern VA.
    These elevated WSSI-P Major probabilities indicate an unusual/rare
    event is increasingly likely.=20


    The probability for significant icing is less than 10 percent.


    Fracasso/Mullinax


    ...Winter Storm Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!4CUOSQKzFnNbuP0ngRlzupRluDzSlOf6XOxWtVIaMamPu= jK5SigKJj5NkEGuj9rswLkOdYSJyPEWhVxQJ46-zwVAXj8$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!4CUOSQKzFnNbuP0ngRlzupRluDzSlOf6XOxWtVIaMamPu= jK5SigKJj5NkEGuj9rswLkOdYSJyPEWhVxQJ46-crIXiPo$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, January 29, 2026 20:15:28
    FOUS11 KWBC 292015
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    315 PM EST Thu Jan 29 2026

    Valid 00Z Fri Jan 30 2026 - 00Z Mon Feb 02 2026


    ...Southern Appalachians, Mid-Atlantic, & Southern New England...=20
    Days 1-3...

    ...A major winter storm is expected to produce heavy snowfall=20
    across the southern Mid-Atlantic, blizzard conditions along the=20
    Mid- Atlantic coasts, & potentially heavy snow in southern New=20
    England...

    Meteorological Overview...

    An arctic air-mass anchored over the eastern U.S. will set the
    stage for an amplifying shortwave trough over the OH Valley to
    produce a major winter storm over the southern Appalachians and=20
    southern Mid-Atlantic beginning Friday afternoon and continuing
    into the weekend. Snow will begin as early as Friday morning=20
    across the TN Valley and east to the southern/central Appalachians=20
    due to low-level WAA, increasing PVA aloft, plus upslope=20
    enhancement into the Appalachians. As the upper trough sharpens=20
    over near the OH/MS Confluence, a robust >100kt 500mb jet streak=20
    will place its divergent left-exit region over the southern Mid-=20
    Atlantic and snow will envelop much of the Appalachians and=20
    Piedmont of the Southeast come early Saturday morning.=20

    By 12Z Saturday, most guidance is in agreement that the 500mb
    shortwave takes on a more neutral tilt (oriented N-S) over the TN
    Valley and becomes a closed low over GA. PVA becomes maximized=20
    over the Southeast while a surface low spawns along a coastal=20
    front east of the Carolinas. As the 850mb low deepens over northern
    GA and heads east into SC, easterly 850mb theta-e advection will=20
    direct low-level moisture around the 850mb low and support a band=20
    of moderate-to-heavy snow from northern GA to central SC. Farther=20
    north, the same tongue of 850mb theta-e is funneling along the=20
    850mb front to the north of the 850mb low track from northern SC=20
    on east through the heart of NC. This is where the deformation zone
    is likely to form, pivoting over central NC and northern SC with=20
    1-2"/hr snowfall rates likely. This band of heavy snow is likely to
    ensue farther east into southeast VA, where 700mb FGEN is more=20
    ideally placed to support strong vertical velocities within a fully
    saturated DGZ. Similar to NC, look for intense bands of heavy snow
    over southeast VA to form late Saturday afternoon and persist into
    Saturday night. These bands of heavy snow in eastern NC and=20
    southeast VA depict 700-500mb lapse rates >6.5C/km Saturday=20
    afternoon and evening. It is here where not only are 2"/hr snowfall
    rates achievable, but so is the likelihood for thundersnow. The
    intense vertical velocities in eastern NC and southeast VA may
    result in some subsidence in north-central NC and south-central VA.
    Snowfall is still likely to reach warning criteria, but these
    regions are potentially susceptible to lesser snowfall amounts as
    they are caught between the influence of the strong upper-low to
    the south, and the strengthening coastal low.

    Speaking of the coastal low, along the coast VA/NC/SC coasts, not=20
    only will the deformation zone of heavy snow pivot through, but the
    explosive deepening of the storm east of Cape Hatteras will=20
    support strong to potentially damaging wind gusts. Latest ECMWF=20
    shows low pressure south of Hatteras is around 1007mb at 12Z=20
    Saturday, then by 12Z Sunday is 972mb east of Hatteras, indicative=20
    of rapid intensification. With strong high pressure to the west, a=20
    strong isallobaric flow will develop in response, creating wind=20
    gusts along the DelMarVa coast on south through the Outer Banks=20
    that could approach hurricane-force at times. These coastal areas=20
    overlap with the ECMWF EFI in >0.8 values for both snow and wind,=20
    making these areas most susceptible to blizzard conditions. Not to=20
    be ignored either, strong wind gusts atop the Smokeys and Blue=20
    Ridge are likely to top 60 mph as well, resulting in possible=20
    blizzard conditions in those higher elevations of the southern=20
    Appalachians. Power outages are likely in some parts of the
    southern Mid-Atlantic, particularly areas at risk for those
    hurricane-force wind gusts along the VA/NC coast.

    While there is still some uncertainty in storm track, most guidance
    (including AIFS ensembles) have continued to trend lower in
    snowfall amounts from northern VA on north and east along I-95 to=20
    the Tri-state area. There remains a high degree of uncertainty over
    southeast MA where the differences in the EPS-AIFS 75th and 25th=20
    percentile snowfall outcomes south of Boston still are quite=20
    striking. The locations that should still contend with periods of=20
    snow are Martha's Vineyard and Nantucket given their closer=20
    proximity to the snow shield.=20

    Snowfall & Impacts...

    WPC probabilities for the duration of the event show moderate-to-
    high chances (50-80%) for snowfall totals >8" in the Blue
    Ridge/Smokeys, west-central NC on east through northern SC,
    southern NC, and along the Tidewater regions of VA/NC. It is
    southeast VA, eastern NC, and southern NC that feature the highest
    odds for snowfall totals >12" at 40-60%. Wilmington, NC has at
    least a 50% chance of receiving >12" of snow. For context, dating=20
    back to 1870, Wilmington, NC has only observed 3 instances where=20
    12" of snowfall occurred: Feb 1896, Feb 1973, and Dec 1989.=20

    The snowfall likely to occur across the Carolinas has a good=20
    chance to be not just significant but historic and highly=20
    disruptive, not just during the event, but for days after it is=20
    long gone. WSSI shows an expansive area of Major Impacts=20
    (considerable disruptions to daily life; dangerous to impossible=20
    travel, widespread closures, disruptions to infrastructure) from=20
    central SC (including Columbia, SC) through the eastern two-thirds=20
    of NC (Charlotte/Raleigh- Durham). The WSSI-P shows low-to-
    moderate chances (20-50%) for Extreme Impacts (per the WSSI=20
    legend: extremely dangerous conditions, life saving actions may be
    needed) in southern NC, including the I-95 corridor from=20
    Fayetteville, NC to Florence, SC. Along the coast, WSSI shows Major
    to locally Extreme conditions along VA Beach on south into the=20
    northern OBX and along the north and east-facing shores facing the
    Pamlico and Albemarle sounds, largely due the blizzard potential=20
    and heavy snow. This speaks to the severity of this major winter=20
    storm in the Carolinas. Lastly, with frigid temperatures in the=20
    storm's wake on Sunday and lasting into Tuesday, the snow will not=20
    melt much following the conclusion of the storm. Any melting that=20
    occurs thanks to daytime heating is likely to cause refreezing on=20
    untreated roads and surfaces. Residents in the Carolinas should=20
    finish preparations as soon as possible, as road conditions will be
    treacherous Saturday and into the first half of next week.

    Elsewhere, travel disruptions are possible as far south and west as
    the Atlanta metro area where the WSSI (as of this discussion's
    issuance) shows Minor Impacts. Look for measurable snow to cause
    hazardous travel as far west as the TN Valley and as far south as
    Savannah where snowfall accumulations up to 1" is possible.
    Moderate Impacts (hazardous travel and some infrastructure
    impacts) are also forecast in Charleston, SC in the Smokeys/Blue=20
    Ridge of western NC/TN, and as far north as the southern Richmond,=20
    VA suburbs. Impacts are still unclear in southeast MA, but expect=20
    blowing snow to cause reduced visibilities in the southeast MA=20
    islands.=20


    ...Great Lakes...
    Days 1-2...

    Cyclonic flow will continue to favor lake effect snow across the=20
    Great Lakes into the first half of the weekend. Frigid 850mb=20
    temperatures will persist with temperatures around -18 to -24C,=20
    which are below the 10th climatological percentile. WNW flow will=20
    turn more northerly (even NNE for a time) as the sharp 500mb=20
    shortwave passes over the Great Lakes tonight. On Friday, northerly
    flow continues Friday with NNE flow possible into Chicagoland=20
    carrying a LES band into the region overnight into Saturday.=20

    Latest guidance has favored the heavier snow over far northwest=20
    IN, although localized totals approaching 4" along the Lake Michigan
    shores in Chicago are possible. Most snowfall winds downs late=20
    Saturday into early Sunday as surface high pressure builds in overhead.
    Single band off Lake Ontario will weaken starting this afternoon=20
    but persist through Friday. For days 1-2, WPC probabilities for at=20
    least 4 inches of snow are >50% over parts of the Michigan U.P. and
    downwind of Lake Ontario near Oswego, where additional snowfall up
    to 8" are possible.

    ...Northern Great Plains & Upper Midwest...
    Days 1-3...

    Two rounds of snow are expected; one this evening and into Friday
    morning, then the other starting late Friday night and continuing
    into the weekend. Weak 850-700mb WAA and FGEN will support light
    snow over the western Dakotas and into the Nebraska Sand Hills
    tonight and Friday AM. Snowfall totals are likely to range between
    1-3" in these areas by the time snow concludes late Friday=20
    morning, with the Black Hills sporting low chances (10-30%) for=20
    snowfall total over 4". By Friday night, a Pacific shortwave trough
    escorts Pacific moisture eastward into the Northern Plains=20
    Saturday morning, then into the Upper Midwest Saturday evening into
    Sunday. Patches of freezing rain in the northern High Plains on=20
    late Friday into Saturday are expected given the favorable=20
    overrunning from WAA at low-mid levels and sub-freezing surface=20
    temps. Farther east, snow is the more likely precip type from the=20
    Red River of the North on south to the Missouri Valley, then east=20
    to the Mississippi river and MN Arrowhead. Snow totals are forecast
    to range between 1-3" in these areas late Saturday into Sunday.=20
    Some hazardous travel is possible, especially where roads=20
    temperatures are likely below freezing in the wake of the recent=20
    extreme cold.


    Mullinax



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9uwfHTIrXu4nB5pX8IiYt7LWwCT8oOZLhh6Q6IBpUX5Qs= 3ag7Wrua_Ul_oXoc_41EI5uC8IA5fYogem_z21P6LZ1O9o$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!9uwfHTIrXu4nB5pX8IiYt7LWwCT8oOZLhh6Q6IBpUX5Qs= 3ag7Wrua_Ul_oXoc_41EI5uC8IA5fYogem_z21PLNrxWmE$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, January 30, 2026 07:40:08
    FOUS11 KWBC 300739
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    239 AM EST Fri Jan 30 2026

    Valid 12Z Fri Jan 30 2026 - 12Z Mon Feb 02 2026


    ...Southern Appalachians, Mid-Atlantic, & Southern New England...=20
    Days 1-3...

    ...A major winter storm is expected to produce heavy snowfall and=20
    blizzard conditions across the southern Mid-Atlantic...

    Meteorological Overview...

    An arctic air mass anchored over the eastern U.S. will set the=20
    stage for an amplifying shortwave trough over the OH Valley to=20
    produce a major winter storm over the southern Appalachians and=20
    southern Mid-Atlantic beginning later this afternoon and continuing
    into the weekend. Snow over the TN Valley this morning will move=20
    into the southern/central Appalachians this afternoon due to low-
    level WAA, increasing PVA aloft, and upslope enhancement. As the=20
    upper trough sharpens over/near the OH/MS Confluence, a robust=20
    100kt 500mb jet streak will place its divergent left-exit region=20
    over the southern Mid-Atlantic and snow will envelop much of the=20 Appalachians and Piedmont of the Southeast early Saturday morning.=20

    On Saturday, the 500mb shortwave will take on a N-S neutral tilt=20
    over the TN Valley and close off as it enters NW GA. PVA becomes=20
    maximized over the Southeast while a surface low spawns along a=20
    coastal front east of the Carolinas (with an additional surface low
    moving out of the Bahamas). As the 850mb low deepens over northern
    GA and heads east into SC, easterly 850mb theta-e advection will=20
    direct low-level moisture around the 850mb low and support a band=20
    of moderate-to-heavy snow from northeastern GA to central SC.=20
    Farther north, the same tongue of 850mb theta-e is funneling along=20
    the 850mb front to the north of the 850mb low track from northern=20
    SC on east through much of NC. This is where the deformation zone=20
    is likely to form, pivoting over central to eastern NC and northern
    SC with 1-2"/hr snowfall rates likely. This band of heavy snow is=20
    likely to reach farther east toward the Outer Banks (HREF=20
    probabilities of >1"/hr at 00Z Sun, the end of the run, are >30%)=20
    where 700mb FGEN is more ideally placed to support strong vertical=20 velocities within a fully saturated DGZ. These bands of heavy snow=20
    in eastern NC and southeast VA depict 700-500mb lapse rates=20
    6.5C/km Saturday afternoon and evening. It is here where not only=20
    2"/hr snowfall rates are achievable, but so is the likelihood for=20 thundersnow. Note that the intense vertical velocities in eastern=20
    NC and extreme southeast VA may result in some subsidence in north-
    central NC and south-central VA. Snowfall is still likely to reach
    warning criteria, but these regions are potentially susceptible to
    lesser snowfall amounts as they are caught between the influence=20
    of the strong upper-low to the south, and the strengthening coastal
    low.

    Speaking of the coastal low, along the VA/NC/SC coasts, not only=20
    will the deformation zone of heavy snow pivot through, but the=20
    explosive deepening of the storm east of Cape Hatteras will support
    strong to potentially damaging wind gusts. ECMWF shows low=20
    pressure south of Hatteras around 1008mb 12Z Saturday dropping to=20
    around 970mb by 12Z Sunday east of Hatteras, indicative of rapid=20 intensification. With strong high pressure to the west, a strong=20
    isallobaric flow will develop in response, creating wind gusts=20
    along the DelMarVa coast on south through the Outer Banks that=20
    could approach hurricane-force at times. These coastal areas=20
    overlap with the ECMWF EFI in >0.8 values for both snow and wind,=20
    making these areas most susceptible to blizzard conditions. Not to=20
    be ignored either, strong wind gusts atop the Smokeys and Blue=20
    Ridge are likely to top 60 mph as well, resulting in possible=20
    blizzard conditions in those higher elevations of the southern=20
    Appalachians. Power outages are likely in some parts of the=20
    southern Mid-Atlantic, particularly areas at risk for those=20
    hurricane-force wind gusts along the VA/NC coast.

    Latest trends nudged the QPF footprint a bit southward but still=20
    focused on NC into SC and grazing southeastern VA. By Sunday, the=20
    trend of the system as it makes its closest pass to New England is=20
    to be a bit farther southeast (away from the coast), and have=20
    trended down the snow there in response. Locations that remain=20
    susceptible are Cape Cod, Martha's Vineyard, and especially=20
    Nantucket where WPC probabilities for at least 4 inches of snow are
    around 50%.


    Snowfall & Impacts...

    For the event, WPC probabilities for at least 8 inches of snow are
    50% from the Blue Ridge/Smokeys eastward across most of NC and=20
    half of SC and along the VA/NC border. Eastern NC has the highest=20
    chances (30-50%) of at least a foot of snow, depending on and band=20 placement. For context, some locations may see snowfall amounts not
    seen since the 1970s/1980s (e.g., Feb. 1973, March 1980, or Dec.=20
    1989) and could be a top ten event snowfall.=20

    The snowfall could also be highly disruptive, not just during the=20
    event, but for days after it is long gone. WSSI shows an expansive=20
    area of Major Impacts (considerable disruptions to daily life;=20
    dangerous to impossible travel, widespread closures, disruptions to infrastructure) from central SC (including Columbia, SC) through=20
    the eastern two-thirds of NC (Charlotte/Raleigh-Durham). Along the=20
    coast, WSSI shows Major to locally Extreme conditions from the=20
    VA/NC border southward into the OBX and along the north and east-=20
    facing shores of the Pamlico and Albemarle sounds, largely due the=20
    blizzard potential and heavy snow. This speaks to the severity of=20
    this major winter storm in the Carolinas. Lastly, with frigid=20
    temperatures in the storm's wake on Sunday and lasting into=20
    Tuesday, the snow will not melt much following the conclusion of=20
    the storm. Any melting that occurs thanks to daytime heating is=20
    likely to cause refreezing on untreated roads and surfaces.=20
    Residents in the Carolinas should finish preparations as soon as=20
    possible, as road conditions will be treacherous Saturday and into=20
    the first half of next week.

    Elsewhere, travel disruptions are possible as far south and west=20
    as the Atlanta metro area where the WSSI shows Minor impacts with a
    chance for an inch or so of snow on Saturday. Measurable snow may=20
    cause hazardous travel as far west as the TN Valley and as far=20
    south as Savannah where snowfall accumulations up to 1" are=20
    possible. Moderate impacts (hazardous travel and some=20
    infrastructure impacts) are also forecast in Charleston (SC), the=20 Smokeys/Blue Ridge of western NC/TN, and as far north as the=20
    southern Richmond, VA suburbs. Impacts are still unclear in=20
    southeast MA, but any snowfall will likely be accompanied by gusty=20
    winds, causing blowing snow and reduced visibilities.=20


    ...Great Lakes...
    Day 1...

    Cyclonic flow will continue to favor lake effect snow across the=20
    Great Lakes for another 36 hours or so. Frigid 850mb temperatures=20
    will persist (around -18 to -24C, which are below the 10th=20
    climatological percentile) over the rapidly freezing lakes. The N-S
    band over Lake Michigan this morning will likely graze the WI/IL=20
    shore before aiming into NW Indiana this evening/overnight as the=20
    elongated vorticity lobe swings through. WPC probabilities for at=20
    least 4 inches of snow are highest (40-60%) around Gary, IN.=20
    Leftover lake snow on northerly flow will relax on Saturday as high
    pressure briefly builds in from the west.=20


    ...Northern Great Plains, Upper Midwest, and western Great Lakes...
    Days 1-3...

    Tonight, a Pacific shortwave trough escorts Pacific moisture=20
    eastward into the Northern Plains by Saturday morning, then into=20
    the Upper Midwest Saturday evening into Sunday. Patches of freezing
    rain in the northern High Plains on late Friday into Saturday are=20
    expected given the favorable overrunning from WAA at low-mid levels
    and sub-freezing surface temps. Farther east, snow is the more=20
    likely precip type from the Red River of the North southward to the
    Missouri Valley, then east to the Mississippi River and MN=20
    Arrowhead/U.P/WI. Snow totals are forecast to range between 1-3" in
    these areas late Saturday through Sunday into early Monday. Some=20
    hazardous travel is possible, especially where roads temperatures=20
    are likely below freezing in the wake of the recent extreme cold.


    Fracasso/Mullinax


    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_3gsfWHd4Rifi_CbV855Uh95BwMUxebkCOtdGLmsOVMQr= 5vQiqjacEqqVbSCNFdjb1Vfzm2V8IUKW9U7ZZxrzndtSh8$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_3gsfWHd4Rifi_CbV855Uh95BwMUxebkCOtdGLmsOVMQr= 5vQiqjacEqqVbSCNFdjb1Vfzm2V8IUKW9U7ZZxr0nsBM1M$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, January 30, 2026 18:35:55
    FOUS11 KWBC 301835
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    135 PM EST Fri Jan 30 2026

    Valid 00Z Sat Jan 31 2026 - 00Z Tue Feb 03 2026


    ...Southern Appalachians, Mid-Atlantic, & Southern New England...=20
    Days 1-2...

    ...A major winter storm is expected to produce heavy snowfall and=20
    blizzard conditions across the southern Mid-Atlantic...

    The synoptic evolution continues to support a major winter storm,
    primarily focused over the Carolinas, but questions about the
    details continue.

    The event begins this evening, as snow breaks out across the
    southern Appalachians of NC/TN. This initial development of snow
    will be in response to increasing synoptic ascent within strong
    mid-level divergence downstream of a pivoting shortwave digging out
    of the Great Lakes. As this shortwave dives southward out of the
    Great Lakes, it will rapidly deepen into an impressive closed low
    by 12Z Saturday over the Tennessee Valley, and then continue to
    dive southeast, reaching the GA/SC coast by 00Z Sunday. This will
    produce extreme anomalies of more than -5 sigma with respect to
    500mb heights according to NAEFS across the Southeast/Gulf Coast,
    indicative of how rare and extreme this setup will be. As the upper
    low deepens and drops southward, forcing will intensify in response
    to not only the mid-level divergence noted above, but additional
    robust height falls, and increasing jet-level diffluence as a
    downstream subtropical jet streaks strengthens across the Gulf and
    then begins to arc poleward along the Southeast coast. This will
    help generate surface cyclogenesis along the coast of the
    Carolinas, with dual low-pressure systems progged, each one
    deepening along the intense baroclinic gradient positioned offshore
    owing to the recent extremely cold air blanketed across the eastern
    CONUS.

    The secondary surface low, which is likely to be the more intense
    feature as it explosively intensifies Saturday night into Sunday
    (maybe reaching into the 960s offshore) is progged to pivot more
    east than northeast along the coast, so the heavy precipitation
    should be generally confined to the Carolinas, southern VA, and
    maybe Cape Cod as it pulls away. While there is continued
    uncertainty into the exact amounts of precipitation due to dry air
    aloft and intense mesoscale ascent that will drive bands of heavy
    snow, there is high confidence in this overall synoptic evolution,
    resulting in high confidence in the most impacted areas.

    The column will be extremely cold, so other than possibly some
    light rain along the coast to start the event, this will be an
    all-snow scenario with above-climo SLRs, a rarity for this part of
    the country. As noted above, the snow begins across the
    Appalachians Friday evening and then expand rapidly to the south
    and east as the upper low dives towards the Gulf and low pressure
    development occurs offshore. This expansion of precipitation will
    be driven primarily by increasing 850mb easterly flow, tapping into
    the growing theta-e ridge offshore, with the resultant WAA leading
    to the expanding snow shield, Some of this WAA could be intense as
    reflected by strengthening 925-700mb fgen, well aligned into the
    deep DGZ (>70% chance of at least 100mb of DGZ depth according to
    the SREF). This will support not only expanding snowfall, but
    intensifying snowfall such that by 00Z/Sunday at least moderate
    snowfall rates should encompass nearly the entirety of the
    Carolinas and into northeast GA and southern VA.=20

    After 00Z Sunday is when the heaviest snow and most notable impacts
    are expected as the low offshore deepens rapidly. This will pivot
    winds to more N/NE across the region, and as a deformation axis
    pivots west of the surface low and the cold conveyor sets up across
    the Atlantic and into the eastern Carolinas, more intense ascent=20
    and greater moisture should result in extreme (for this region)=20
    snow rates. Cross-sections indicate a broad region of favorable=20
    conditions for CSI, or even CI (thundersnow), and the HREF snow-=20
    rate probabilities peak above 50% for 1"/hr suggesting at least a=20
    potential for 2"/hr within a pivoting band somewhere in eastern NC=20
    or SC, and this is additionally supported by the WPC prototype
    snowband tool. These heavy snow rates will be accompanied by=20
    strong winds that may gust 35-50 mph, higher at the coast and in=20
    the mountains, suggesting near blizzard conditions in many areas.=20
    While uncertainty remains into how dry air in the mid- level may=20
    impact snow amounts on the broad scale, locally very significant=20
    snowfall accumulations are likely, especially within these bands,=20
    during D2. By Sunday afternoon the low will pull away bringing an=20
    end to the snowfall and leaving just cold windy conditions in its=20
    wake.

    The exception will be across far southeast Massachusetts and onto=20
    Cape Cod and the Islands where, despite a subtle southeast trend in
    today's model guidance, periods of moderate snow are still expected
    due to onshore flow and sufficient synoptic ascent into the
    moistening column. A period of moderate snowfall is likely, with
    some local enhancement south of Boston and on the Outer Cape due to
    ocean influences, Sunday aftn/eve.

    WPC probabilities for the event are quite robust for both the
    Appalachians and eastern North Carolina, where they are above 50%
    for 8+ inches, and 30-50% for 12+ inches. The greatest potential=20
    for more than 12 inches appears to be eastern NC where the=20
    deformation band may pivot, but a widespread 4-8" snowfall appears=20
    likely from southern VA through northern SC, with impactful=20
    accumulations expected in areas like Richmond, VA, Charlotte and=20
    Raleigh, NC, Columbia, SC, and even into Atlanta, GA. Farther=20
    northeast, WPC probabilities are 30-50% for 4+ inches across the=20
    Cape and Islands.

    Key Messages are in effect for this storm, and are linked below
    (Key Message #2).=20


    ...Great Lakes...
    Day 1...

    Potent shortwave diving southward within broad cyclonic flow into=20
    the Tennessee Valley Saturday morning will rapidly sharpen the
    eastern CONUS trough leaving pronounced CAA on northerly flow in
    its wake. This will result in continued lake effect snow (LES),
    especially in the favored north snow belts south of Lake Ontario
    and especially south of Lake Michigan where the long fetch of the
    lake will be maximized to produce a narrow band of heavy snowfall.
    Although the lakes are cooling and have much higher ice coverage
    than a week or two ago, frigid 850mb temperatures moving overhead
    will create strong delta-Ts to support snowfall rates that have a
    30-40% chance (from the HREF) of exceeding 1"/hr, greatest across
    NW Indiana. While some light accumulations are likely south of Lake
    Ontario, WPC probabilities for 4+ inches are confined to NW IN
    where they reach 30-50%.


    ...Northern Plains through the Upper Midwest and Great Lakes...=20
    Days 1-3...

    A shortwave emerging from the Pacific will crest the ridge over the
    Pacific Northwest and then dive slowly southeast into the Northern
    Plains and then amplify into a deeper trough as it moves into the
    Great Lakes and then elongate towards the Tennessee Valley. This
    feature will generally be of modest amplitude and remain
    progressive, so large scale forcing for ascent will be modest and
    driven by mid-level divergence downstream of the trough overlapping
    modest warm advection/isentropic ascent. The result of this will be
    axes of both light freezing rain and snow in many areas from
    eastern MT through the western Great Lakes. WPC probabilities for
    2"+ of snowfall are as high as 30-50% D2 across central/northern
    MN, and similar for parts of the U.P. and western L.P. of MI D3.
    For freezing rain, WPC probabilities are as high as 30% for 0.1"=20
    in western ND on D1, but are generally less than 10% elsewhere=20
    through the period. However, light freezing rain accreting above=20
    0.01" is possible for much of Montana and the Dakotas.

    Weiss



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_zv2HEUaCxHmrxcjxPpQ_d45hb_EFdwDQXzo01Egj7qkP= UXe0KoqO0O81tc8GJAqH6nRw9ZPdRN7lhhSqjXZph7rlAQ$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_zv2HEUaCxHmrxcjxPpQ_d45hb_EFdwDQXzo01Egj7qkP= UXe0KoqO0O81tc8GJAqH6nRw9ZPdRN7lhhSqjXZerjYTzs$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, January 31, 2026 07:10:33
    FOUS11 KWBC 310710
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    210 AM EST Sat Jan 31 2026

    Valid 12Z Sat Jan 31 2026 - 12Z Tue Feb 03 2026


    ...Southern Appalachians, Mid-Atlantic, & Southern New England...=20
    Days 1-2...

    ...A major winter storm is expected to produce heavy snowfall and=20
    blizzard conditions across the southern Mid-Atlantic...

    Sharp mid-level trough over the mid-MS Valley early this morning=20
    will close off into a potent upper low over Middle TN by 12Z. The=20
    pattern over the East Coast will feature an increasingly amplified=20
    pattern (e.g., strengthening S-shaped upper jet) that will support=20
    explosive cyclogenesis off the Carolina coast this=20
    evening/overnight. With an arctic air mass already in place, nearly
    all of the precipitation will be snow even at onset. The system=20
    will quickly lift up the coast (outside the 40/70 benchmark) and=20
    clip southeastern New England as it races into Atlantic Canada=20
    tomorrow.=20

    First part of the system is underway over the southern=20
    Appalachians with light to modest snow over the Smokeys into SW VA=20
    beneath lower-level FGEN and incoming height falls/PVA. Snow will=20
    expand southward today over WNC and Upstate SC as well as northeast
    GA as the upper low tracks over ATL to CHS by this evening. To its
    north, near the path of the developing 850mb low, the snow could=20
    fall heavy at times today with 1"/hr rates possible (10-40% chance=20
    per the CAM guidance) into the Charlotte metro. As the upper low=20
    reaches the coast around 06Z Sun, banded snow could sink=20
    southeastward into northeastern SC (Myrtle Beach/The Grand Strand).
    By this time, the coastal low will have begun its rapid=20
    intensification, which leads into the other part of the system.=20

    With the coastal low intensifying through the 990s to 970s mb, N=20
    to NE flow at the surface over eastern and northeastern NC into=20
    extreme southeastern VA will increase as snow continues to fall.=20
    The increasing 850mb northeasterly/easterly flow, tapping into the=20
    growing theta-e ridge offshore, coupled with WAA and strengthening=20
    925-700mb FGEN, will support >1"/hr rates over eastern NC after 00Z
    Sun. Deformation axis should pivot west of the surface low and the
    cold conveyor sets up across the Atlantic and into the eastern=20
    Carolinas to support those rates. Cross-sections indicate a broad=20
    region of favorable conditions for CSI, or even CI (thundersnow),=20
    which is not unusual in highly dynamic and rapidly intensifying=20
    systems. The column is quite cold, and SLRs should be well above=20
    climo with a deep DGZ (>13:1 to near 20:1). These heavy snow rates=20
    will be accompanied by strong winds that may gust 35-50 mph, higher
    at the coast, suggesting near-blizzard conditions in many areas.

    One question in the forecast, per the 00Z guidance, is what=20
    happens in between these two main drivers of heavier snow areas;=20
    i.e., in the I-85/95 corridors in NC. Some CAM guidance shows an=20
    extreme min (near zero snow) while other guidance shows at least=20
    several inches. CAM guidance could be overdoing the mesoscale=20
    response of oscillatory subsidence/lift surrounding the system, but
    it certainly is unusual to see this much spread just before the=20
    start of the event. Trimmed down the amounts here from the previous
    forecast but not to the extent of the 00Z CAMs.=20

    By Sunday afternoon the low will pull away bringing an end to the=20
    snowfall and leaving just cold windy conditions in its wake. To the
    northeast, despite a track just outside the 40/70 benchmark, the=20
    expansive system will likely clip far southeast Massachusetts=20
    (southeast of I-95) and Cape Cod and the Islands where periods of=20
    moderate snow are expected due to onshore flow and sufficient=20
    synoptic ascent into the moistening column. A period of moderate=20
    snowfall is likely, with some local enhancement south of Boston and
    on the Outer Cape due to ocean influences, Sunday aftn/eve.

    WPC probabilities for at least 6 inches of snow are >50% over much
    of western NC, across the border to upstate SC, southeastward to=20
    the coast, and the northeastward up the coast into extreme=20
    southeastern VA. Lower probabilities around 30% exist along the VA=20
    border and over southwestern SC. Mesoscale bands will likely=20
    enhance snowfall over some areas resulting in >10-12" snow. A=20
    broader area of light snow is expected surrounding the system, with
    WPC probabilities for at least 1" of snow >50% as far west as=20
    Atlanta, south to near Savannah, and on the north side up to=20
    Richmond, VA and Salisbury, MD on the DelMarVa. In MA, WPC=20
    probabilities for at least 4 inches of snow are >30% over the Cape=20
    and Martha's Vineyard but >50% over Nantucket.=20


    Key Messages are in effect for this storm, and are linked below=20
    (Key Message #2).=20


    ...Northern Plains through the Upper Midwest and Great Lakes...=20
    Days 1-3...

    And advancing warm front over the western High Plains this morning
    will continue eastward, bringing the chance for some snow and=20
    freezing rain as milder Pacific air overruns the cold surface. The=20
    system will continue eastward Sunday into the western Great Lakes=20
    and through MI to the eastern Great Lakes Monday. Amounts will be=20
    light, generally 1-3", as the system remains progressive. WPC=20
    probabilities for at least 4" are around 10% over portions of the=20
    Red River Valley (ND/MN border) and perhaps the Keweenaw Peninsula=20
    wit some lake enhancement after the front moves to the east.=20


    Fracasso/Weiss


    ...Winter Storm Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!4XEwcjZbPCsaopLdDZHr3UrVyP5HfOPX16r-Ffei8ZPsV= DY7_6OXc-aU-DKV2da-bl6n6tCr8zwqm953Cu8HX5EO-2M$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!4XEwcjZbPCsaopLdDZHr3UrVyP5HfOPX16r-Ffei8ZPsV= DY7_6OXc-aU-DKV2da-bl6n6tCr8zwqm953Cu8H32009l4$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, January 31, 2026 19:37:04
    FOUS11 KWBC 311936
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    236 PM EST Sat Jan 31 2026

    Valid 00Z Sun Feb 01 2026 - 00Z Wed Feb 04 2026


    ...Southern Appalachians, Mid-Atlantic, & Southern New England...=20
    Day 1...

    ...A major winter storm will produce heavy snowfall across the
    southern Mid-Atlantiuc and blizzard conditions along the North
    Carolina coast through tonight and into Sunday morning...

    The major winter storm is unfolding with periods of snow, falling=20
    heavily at times, from the southern Appalachians and eastern GA on=20
    east through the Carolinas and into far southern VA. This morning,=20
    the 850mb low has formed and is tracking towards southern SC with a
    tongue of rich 850mb theta-e air rotating around the northern and=20
    western flanks of the low. As the low strengthens, so does the=20
    easterly fetch supplying Atlantic moisture, resulting in a=20
    broadening shield of snow from as far west as the Atlanta metro to=20
    even as far south as Savannah, GA today. As strong 500mb PVA moves
    in aloft, a band of heavy snow is likely to unfold over eastern GA
    that could then pivot over southern SC, including the Charleston=20
    metro area. The heaviest snow rates are likely to occur north of=20
    the 850mb low track where easterly low-level winds are enhanced via
    upslope flow from the hills near Charlotte on west into the=20
    southern Appalachians. Snowfall rates of 1-2" per hour are likely=20
    there, resulting in dangerous to even impossible travel conditions.
    WPC probabilities show moderate chances (40-60%) for additional=20
    snowfall totals >4" from Charlotte on south into central SC and=20
    eastward to northeast SC and the Cape Fear Tidewater region.=20

    Central NC and southern VA are caught between the impressive=20
    dynamics closer to the highly anomalous upper-low to the south and
    west, and the developing coastal low that will rapidly strengthen=20
    east ot the Outer Banks today and into tonight. Guidance has come into
    better agreement on a depression in the expected QPF footprint=20
    around the Raleigh-Durham area on north and east along I-85 into=20 south-central VA. While totals have trended down, it is=20
    exceptionally cold with highs unlikely to get above the mid 20s=20
    today. Plus, occasionally gusty winds this afternoon and evening=20
    will cause reduced visibilities and blowing snow on roads. WPC=20
    probabilities still show moderate-to-high chances (50-80%) for=20
    snowfall totals >2" in these areas, with better odds for >4" on=20
    southward along I- 95 and I-40. Snow will have no trouble sticking=20
    and travel will be hazardous through this evening and into tonight.
    Expect slick roads to persist into Sunday as temperatures will=20
    struggle to get above freezing, and any melting that does occur on=20
    Sunday on roadways has a high chance to refreeze Sunday night and=20
    Monday morning.

    Farther east into eastern NC and southeast VA, the storm system
    along the coast will rapidly strengthen by as much as 40mb in 24
    hours. Not only will a band of 1-2"/hr snowfall rates ensue this
    afternoon and into tonight, but wind will ramp up in intensity
    significantly, especially along the Outer Banks and on north/east
    facings shores of the Pamlico and Albemarle Sounds. Steepening
    lapse rates as the mid-upper level low approaches the warmer shelf
    waters will also support some instability in the 850-500mb layer,=20
    allowing for thundersnow to be a potential phenomenon for those in=20
    eastern NC. Snow will continue over the eastern tidal areas of NC=20
    and southeast VA through early Sunday morning, but snow should=20
    taper off by midday Sunday as the powerful winter storm races east=20
    into the west Atlantic. WPC probabilities show moderate- to-high=20
    chances (50-80%) for snowfall totals >6" from the Myrtle Beach area
    and the Cape Fear region on north through much of eastern NC.=20
    Given the robust 1-2"/hr rates in eastern NC, there is a low-to-
    moderate chances (30-50%) for localized snowfall totals to surpass=20
    12" by the time this event concludes late Sunday morning. As=20
    mentioned above, the bitter cold in wake of the storm will keep=20
    travel on all roadways across eastern and southern NC treacherous=20
    into the start of the work/school week.=20

    Lastly, trends have been to gradually decrease snowfall totals in
    southeast MA, although some measurable snow and blowing snow is
    likely over Martha's Vineyard, Nantucket, and the MA Capes. WPC
    probabilities show low-to-moderate chances (30-60%) for snowfall
    totals >4" here, with Nantucket sporting the highest chances for
    6" given their closer proximity to the winter storm on Sunday.

    Key Messages are in effect for this storm, and are linked below=20
    (Key Message #2).=20


    ...Northern Plains through the Upper Midwest and Great Lakes...=20
    Days 1-3...

    An advancing warm front associated with low pressure over southern
    Canada is tracking across the North Central U.S. today will=20
    continue eastward, producing light snow and minor freezing rain in=20
    the Northern Plains as milder Pacific air overruns the cold=20
    surface. The warm front marches eastward Sunday into the Upper
    Midwest and Great Lakes, then into Michigan and the eastern Great=20
    Lakes Monday. Amounts will be light, generally 1-3", as the system=20
    remains progressive. Another round of light snow arrives in the
    northern High Plains on Monday and ending Monday night, but totals
    are likely to be below 3 inches.


    ...Ohio Valley & Central Appalachians...
    Day 3...=20

    The shortwave trough responsible for light snow in the northern
    High Plains on Monday dives south into the Middle MS Valley early
    Tuesday morning and races into the OH Valley by Tuesday afternoon.
    Weak 850-700mb WAA and a tongue of 700-300mb moisture aloft will be
    available aloft and will allow for snowfall. Most snowfall amounts will
    be generally a coating-2", although the central Appalachians in=20
    eastern WV have low-to-moderate chances (30-50%) for snowfall=20
    amounts >2". This weak feature has a chance to produce light snow=20
    in portions of the Mid-Atlantic on Wednesday.


    Mullinax



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_FsdXoLtiJKgZ9SEV8EVy4DoOUHafubqMkLCzThr-B36g= 9DWF1LlOJ9JGlBYJP21r3EHc_EHIKUVPBZmdQbPfoMGK1g$=20

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_FsdXoLtiJKgZ9SEV8EVy4DoOUHafubqMkLCzThr-B36g= 9DWF1LlOJ9JGlBYJP21r3EHc_EHIKUVPBZmdQbPrJyhzgw$=20



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, February 01, 2026 06:30:42
    FOUS11 KWBC 010630
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    130 AM EST Sun Feb 1 2026

    Valid 12Z Sun Feb 01 2026 - 12Z Wed Feb 04 2026


    ...Southeastern Massachusetts...
    Day 1...

    The powerful winter storm exiting the Carolinas this morning will=20
    graze southeastern New England today with generally light snow but=20
    very gusty winds. WPC probabilities for at least 4 inches of snow=20
    are 10-30% over Nantucket and into parts of Cape Cod (e.g.,=20
    Chatham).=20


    ...Northern Plains through the Upper Midwest and Great Lakes...=20
    Days 1-3...

    A surface front will move out of the Upper Midwest into the=20
    western Great Lakes today then into Michigan and the eastern Great=20
    Lakes Monday. Snow will be light, generally 1-3", as the system=20
    remains progressive. Another round of light snow arrives in the=20
    northern High Plains on Monday and ending Monday night, but totals=20
    are likely to be below 3 inches. Some areas in the U.P. may see=20
    several inches of the three-day period with modest lake effect snow
    behind the front.=20


    ...Ohio Valley & Central Appalachians...
    Day 3...=20

    The shortwave trough responsible for light snow in the northern=20
    High Plains on Monday will dive into the Middle MS Valley early=20
    Tuesday morning and race into the OH Valley by Tuesday afternoon=20
    and the Mid-Atlantic by Wednesday morning. Weak 850-700mb WAA and=20
    mid-level moisture will favor light snowfall in a west-to-east=20
    areas. Most snowfall amounts will be generally a coating-2", but=20
    some upslope enhancement into the central Appalachians may allow=20
    for a bit more. Here, WPC probabilities for at least 4 inches of=20
    snow are low (10-20%). Light snow will extend eastward into the=20
    Mid-Atlantic early Wednesday.


    Fracasso


    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9GBpM9epRWaJGrcPUfEKW7ns0MQShIt24-3aSTYra4iBS= yEc4zdUJy3kS0uC9meUdSdqsB6te8uKUm4NjS4o-T7c-Og$=20


    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, February 01, 2026 18:00:59
    FOUS11 KWBC 011800
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    100 PM EST Sun Feb 1 2026

    Valid 00Z Mon Feb 02 2026 - 00Z Thu Feb 05 2026

    ...Northern Plains through the Great Lakes...=20
    Days 1-2...

    A shortwave on the upstream side of an amplified trough (500mb
    heights below the 1st percentile according to NAEFS) will dig
    southeast from Saskatchewan while a secondary shortwave deepens
    into a closed low over Ontario. Together, these features will drive
    a surface cold front eastward from the Northern Plains to the Great
    Lakes D1 before continuing into the Ohio Valley D2. The overlapping
    ascent between height falls/PVA and low-level convergence, along
    with modest frontogenesis and subtle WAA will result in an axis of
    light to at times moderate snow, with the heaviest likely occurring
    in response to lake enhancement east of Lake Michigan and across
    the U.P. in the NW snow belts. WPC probabilities are modest overall
    as available moisture is limited, but locally as much as 4" of snow
    is possible (10-30%) across the U.P. and far NW L.P., with less
    than 2" expected elsewhere. Additionally, some light freezing rain
    is also possible driven by dryness within the DGZ, and WPC
    probabilities for 0.01+" of ice are 10-30% across portions of the
    Dakotas D1.


    ...Ohio Valley, Central Appalachians, and Mid-Atlantic...=20
    Days 2-3...

    A fast moving shortwave diving out of Alberta will drop southeast
    around the western CONUS high and into the Mid-Mississippi Valley
    Tuesday morning. This shortwave will amplify, at least subtly, as
    it translates to the southeast, maintaining a positive tilt but
    interacting with a cold front digging across the Ohio Valley. At
    the same time, a subtropical jet streak draped along the Gulf Coast
    will gradually intensity in response to the trough amplification,
    and begin to pivot poleward, with the response to this evolution
    being a surge in moisture lifting out of the Gulf noted by a strung
    out theta-e ridge from the FL Panhandle into the Mid-Atlantic. This
    moisture return will be aided by at least modest WAA, and the
    guidance has trended upward just a bit in its QPF potential, and
    has shifted northward somewhat as well.

    The WAA lifting isentropically atop the cold front into the colder
    airmass should result in a swath of light to moderate snowfall,
    although locally heavier rates are possible due focused fgen into
    the deepening DGZ, and this is reflected by significant spread in
    the latest WSE plumes, despite a focus of mostly light snowfall
    amounts. Current WPC probabilities are low (10-30%) D2 for at least
    2 inches across the Central Appalachians of WV (where upslope
    enhancement is likely), and moderate (30-50%) in that same area D3
    suggesting localized totals of 4" are possible. Elsewhere, WPC
    probabilities suggest moderate risk (30-70%) for more than 1 inch=20
    across the lower Ohio Valley and a 10-30% for similar accumulations into
    the Mid- Atlantic states including Washington, D.C.

    Some light freezing rain is also possible with this wave as it
    swings eastward, mostly due to loss of cloud ice vs warm nose
    development, which could result in a swath of ice accretion above
    0.01" (10-30% chance) from western KY/TN into VA/NC. Any ice is
    hazardous, but this could be more problematic than usual due to
    continued recovery efforts from the recent winter storms.


    ...Pacific Northwest...
    Day 1...

    A modest Pacific jet streak will lift northeast atop a west coast
    ridge Monday, bringing with it a brief period of IVT exceeding the
    90th climatological percentile according to NAEFS. A warm front
    will push onshore and lift northeast concurrently with this jet
    streak, leading to a brief period of enhanced WAA/precipitation
    before snow levels climb rapidly into D2. This will result in a
    period of rain and snow across the Washington Cascades, and
    although snow level forecasts are generally above pass level, a few
    inches of snow is possible between 3000-4000 ft before turning to=20
    rain. WPC probabilities for 4+ inches of snow are above 70% only in
    the higher Washington Cascades, but a few slushy inches of=20
    accumulation is forecast at Stevens Pass leading to hazardous
    travel Monday afternoon.

    Weiss


    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9YRGIGSlDRwz1Kt4s7H_JQxQxrQrLi-hlxXkhTcc2PeqV= OUwi_taivHgsFXvEnCrMLHMjTJRc9mduyxC6l5q8VK4ssU$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, February 02, 2026 07:14:06
    FOUS11 KWBC 020713
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    213 AM EST Mon Feb 2 2026

    Valid 12Z Mon Feb 02 2026 - 12Z Thu Feb 05 2026


    ...Pacific Northwest...
    Day 1...

    A weak shortwave and surface warm front will move through the
    region this morning with some light snow for areas mainly above
    4000ft, with snow levels rising sharply later today. WPC
    probabilities for at least 4 inches of snow are >50% above 4000ft
    or so.

    ...Great Lakes...
    Day 1-1.5...

    Weak system will spread slight snow across the Great Lakes (1-2")
    today into Tuesday with some lake effect snow behind it, mostly
    over the U.P. of Michigan. There, WPC probabilities for at least 4
    inches of snow are 20-40%.

    ...Northern Plains...
    Day 1...

    A shortwave in southern Canada will dive southeastward through
    North Dakota this morning, with generally light to locally modest
    snow along a thermal gradient. Some banded snow could develop and
    support a few inches of snow, and WPC probabilities for at least 4
    inches are 30-70% over north central North Dakota.

    ...Ohio Valley, Central Appalachians, and Mid-Atlantic...
    Days 2-3...

    The shortwave over the northern Plains Day 1 (above) will dive
    into the Mid-MS Valley tomorrow morning and through the Ohio Valley
    tomorrow evening. At the same time, Gulf moisture will lit
    northeastward through the Lower MS Valley to yield some light snow
    on the northern side of the precip shield. WAA-driven snow is
    likely along the Ohio River Tuesday morning eastward to the central Appalachians tomorrow evening and into early Wednesday, also
    spreading to the Mid-Atlantic. Amounts will generally be light, but
    some upslope enhancement in eastern WV could yield a few inches of
    snow. WPC probabilities for at least 4 inches of snow are around
    30-40% above 3000ft. 1-3" of snow is possible (>50% chance) from
    around Cincinnati eastward. Lower chances of just 1" are seen along
    the I-95 corridor from DC to PHL, but this could coincide with the
    Tuesday evening rush hour or possibly Wednesday morning depending
    on the speed of the system.

    Some light freezing rain or drizzle is also possible with this
    wave over KY/TN into VA/NC. Any ice is hazardous, but this could be
    more problematic than usual due to the recent winter storm(s).


    Fracasso


    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, February 02, 2026 19:35:30
    FOUS11 KWBC 021935
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    235 PM EST Mon Feb 2 2026

    Valid 00Z Tue Feb 03 2026 - 00Z Fri Feb 06 2026


    ...Great Lakes...
    Days 1-2...

    A weak system will continue to spread light snow showers across
    the Great Lakes tonight into Tuesday with some lake effect snow
    following in its wake. Snowfall accumulations of 1-2" are likely
    across portions of MI and western NY, with localized 20-40%
    probabilities of >4" in the U.P of MI and localized 40-60%
    probabilities downwind of Lake Ontario.


    ...Ohio Valley, Central Appalachians, and Mid-Atlantic...
    Days 1-3...

    A shortwave over the northern Plains will dive into the Mid-MS
    Valley by Tuesday morning before reaching the Ohio Valley by
    Tuesday evening. Ahead of this wave, weak surface low pressure will
    develop over the Lower MS Valley, helping to draw Gulf moisture
    northward. The increasing moisture and warm air advection combined
    with large scale forcing for ascent within the left exit region of
    a strengthening 250mb 100kt+ jet streak will yield a swath of
    banded snow from southeast IN and southern OH Tuesday morning
    eastward to the central Appalachians Tuesday evening into Wednesday
    morning. WPC probabilities for snowfall >2" are 30-60% across a
    fairly narrow corridor from southeast IN eastward along and just
    north of the Ohio River and into WV. Banded snowfall could also
    lead to localized higher amounts, with low but not zero
    probabilities of >4" around 5-10%. Upslope enhancement may also
    push accumulations above 4" in the higher elevations of WV, with
    probabilities of 20-40% mainly above 3000ft.

    Some light snow or flurries could survive the trip over the
    central Appalachians into parts of the Mid-Atlantic late Tuesday
    night into Wednesday morning, but trends for even just 1" of snow
    have been decreasing with probabilities now only 10-20% across
    portions of northern VA, northern MD, DE, and southern NJ. Still,
    any snow combined with the recent cold and timing of early morning
    rush hour could be enough to cause localized travel concerns. What
    could be more interesting and worth monitoring is how much more the
    wave develops as it begins to exit the Mid-Atlantic coast
    Wednesday afternoon and evening. Latest trends have been a bit more
    wintry across parts of southern VA and northern NC, and while poor
    thermals are likely limiting probabilities of accumulating
    snowfall at the moment, a deeper wave and greater dynamic cooling
    could change that in the coming days.

    In between the transition from snow to rain, some light freezing
    rain or drizzle is also possible with this wave over KY/TN into
    VA/NC. Any ice is hazardous, but this could be more problematic
    than usual due to the recent winter storm(s).


    Miller


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, February 03, 2026 08:04:37
    FOUS11 KWBC 030804
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    304 AM EST Tue Feb 3 2026

    Valid 12Z Tue Feb 03 2026 - 12Z Fri Feb 06 2026


    ...Great Lakes...
    Day 1...

    A weak system moving through the Great Lakes this morning will spread
    light snow showers over the region with some lake effect snow
    following in its wake. Snowfall accumulations of 1-3" are likely
    across portions of the U.P. of Michigan and near Watertown, NY. WPC probabilities of >4" are low (10-20%).

    Day 3...

    A 140kt jet over south central Canada Thursday will help push a
    warm front through the western Great Lakes, followed by a strong
    arctic cold front that will cross into the region by Friday
    morning. This will bring a period of snow focused on Michigan which
    will lie near/north of the stronger height falls along the fronts.
    Through 12Z Friday, generally light snow but increasing winds over
    the region will usher in much colder air. WPC probabilities for at
    least 4 inches of snow through 12Z Fri are low (10%) but blowing
    snow could be the bigger hazard, especially near the lake shores.


    ...Ohio Valley, Central Appalachians, Mid-Atlantic, Carolinas...
    Days 1-2...

    A shortwave over the Corn Belt this morning will reach the Ohio
    Valley this evening. Ahead of this wave, weak surface low pressure
    will develop over the Lower MS Valley, helping to draw Gulf
    moisture northward. The increasing moisture and warm air advection
    combined with large-scale forcing for ascent within the left exit
    region of a strengthening 250mb 100kt+ jet streak over the Mid-
    South will yield a swath of banded snow from southeast IN and
    southern OH eastward to the central Appalachians today into tonight.
    Amounts will be light (Minor impacts per the WSSI) and WPC
    probabilities for snowfall >2" are 30-60% across a fairly narrow
    corridor from northern KY (CVG) eastward along and just north of
    the Ohio River and into WV. Banded snowfall could also lead to
    localized higher amounts, with low but non-zero probabilities of
    4" around 5-10%. Upslope enhancement may also push accumulations
    above 4" in the higher elevations of WV, with probabilities of
    20-40% mainly above 3000ft.

    Some light snow should crest the central Appalachians into parts
    of the Mid-Atlantic late Tuesday night into Wednesday morning, but
    this can sometimes dry up east of I-81. WPC probabilities for 1" of
    snow are generally <15% along the I-66/Rt 50 corridor across
    northern VA, DC, MD, and into DE. Still, any snow combined with
    the recent cold could be enough to cause localized travel
    concerns.

    As the front continues southeastward, trailing shortwave energy may
    slow the southern portion of the front over the Southeast, allowing
    a weak area of low pressure to form over the southern Appalachians
    on Wednesday. As the low moves slowly through GA/SC Wednesday
    evening and off the coast early Thursday, moisture will linger over
    southern VA and much of northern/western NC where temperatures are
    marginally supportive of snow. During the overnight hours, dynamic
    cooling could support some light accumulation of 1-2" over
    southwestern VA and northern NC where WPC probabilities of >2" of
    snow are 30-60%.

    At the same time, enough northerly component of the wind could
    drain some sub-freezing boundary layer air into eastern NC and
    support light icing of around 0.01" or so. Any ice is hazardous,
    but this could be more problematic than usual due to the recent
    winter storm(s).


    Fracasso/Miller



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, February 03, 2026 19:00:15
    FOUS11 KWBC 031900
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    200 PM EST Tue Feb 3 2026

    Valid 00Z Wed Feb 04 2026 - 00Z Sat Feb 07 2026


    ...Ohio Valley, Central Appalachians, Mid-Atlantic, Carolinas...=20
    Days 1-2...

    Increasing moisture and warm air advection ahead of a weak surface
    low over the Mid South combined with large-scale forcing for=20
    ascent within the left exit region of a strengthening 100kt+ upper=20
    level jet streak will yield a swath of snow from eastern KY eastward
    to the central Appalachians tonight into early Wednesday. Amounts=20
    will be light (Minor impacts per the WSSI) and WPC probabilities=20
    for snowfall >2" are 30-60% mainly across the higher elevations of=20
    WV and southwest VA.

    Some light snow should also crest the central Appalachians into=20
    parts of the Mid-Atlantic late tonight into Wednesday morning, but
    this can sometimes dry up east of I-81. WPC probabilities for 1"=20
    of snow are generally <15% along the I-66/Rt 50 corridor across=20
    northern VA, DC, MD, and into DE. Still, any snow combined with the
    recent cold could be enough to cause localized travel concerns,
    particularly during the Wednesday morning commute.

    As the front continues southeastward, trailing shortwave energy may
    slow the southern portion of the front over the Southeast, allowing
    another weak area of low pressure to form over the southern=20
    Appalachians on Wednesday. As the low moves slowly through GA/SC=20
    Wednesday evening and off the coast early Thursday, moisture will=20
    linger over southern VA and much of northern/western NC where=20
    temperatures are marginally supportive of snow. During the=20
    overnight hours, dynamic cooling could support some light=20
    accumulations around an inch or so across southern VA and northern
    NC, especially across the higher elevations of southwestern VA and
    northwest NC where WPC probabilities of >2" of snow are 20-40%.

    In the wake of the departing low pressure system, lingering low-=20
    level upslope moisture combined with mid-level drying may lead to a
    period of freezing drizzle across parts of eastern KY, southwest=20
    VA, eastern TN, and western NC late tonight into Wednesday morning.
    Anywhere the freezing drizzle is more persistent could produce a=20
    light glaze of ice. Additionally, enough northerly component of the
    wind could drain some sub-freezing boundary layer air into far=20
    southeastern VA and eastern NC, supporting light icing of around=20
    0.05" or so later Wednesday night into early Thursday morning.=20
    While any ice is hazardous, the icing noted above could be more=20
    problematic than usual due to the recent winter storm(s).


    ...Great Lakes, Central Appalachians, Mid-Atlantic...=20
    Day 3...

    A 140kt upper level jet over south central Canada Thursday will=20
    help push a warm front through the western Great Lakes, followed by
    a strong Arctic cold front that will dive to the south and east across
    the region through the day on Friday. The left exit region of this
    jet combined with a potent vort max will increasingly support=20
    large scale forcing for ascent, with weak surface low development=20
    possible downstream of the western Great Lakes. This will support=20
    widespread snow showers and the potential for snow squalls from
    MI and western NY to OH, PA, and WV starting late Thursday night=20
    and continuing through the day on Friday. Some of the stronger=20
    showers and squalls are looking increasingly likely to spill over=20
    the central Appalachians into parts of the Mid-Atlantic later in
    the afternoon, possibly impacting the evening commute. WPC=20
    probabilities for >2" of snow are 40-70% across parts of MI,=20
    northeast OH, northwest PA, and the higher elevations of southwest=20
    PA and WV. Probabilities for >4" of snow are 10-20% for portions of
    the U.P. of MI, northeast OH, and WV.=20

    In the wake of the Arctic front, a blast of bitterly cold air will
    encompass much of the Northeast heading into the weekend. For more
    details, please reference the Extreme Cold Key Messages in the link
    provided below.


    Miller/Fracasso


    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5j_1Fl9dotMFlsl07RquALPtLY120Rf8RXpm3UvO9h2Aq= WTyEVokCe1dREqejgH5zKFQcTSSV5HeegGtRiqqlHSH2qw$=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, February 04, 2026 07:16:15
    FOUS11 KWBC 040716
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    216 AM EST Wed Feb 4 2026

    Valid 12Z Wed Feb 04 2026 - 12Z Sat Feb 07 2026


    ...Southern Mid-Atlantic...
    Day 1...

    A cold front over the Southeast this morning and area of low=20
    pressure over the southern Appalachians will make a slow march=20
    eastward today with rain over much of the region but some light=20
    snow on the northern side of the precipitation shield. Trailing=20
    shortwave energy from the Lower MS Valley/Mid-South will slow the=20
    front a bit tonight as temperatures cool just enough over southern=20
    VA into northern NC for snow to fall and accumulate. In addition,=20
    lingering moisture over eastern NC tonight combined with mid-level=20
    drying may lead to some freezing rain and freezing drizzle. Though=20 accumulations will be light (0.01-0.05"), any freezing rain is=20
    impactful to untreated surfaces. Precipitation will end from west=20
    to east Thursday.

    WPC probabilities of at least 2 inches of snow are 20-50% over=20
    southwestern VA and barely 10% over northern/northeastern NC.=20


    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-3...

    A warm front will push into the Upper Midwest and western Great=20
    Lakes, aided by a 140kt upper level jet over south central Canada=20
    on Thursday. Light and broad WAA-driven snow is forecast for=20
    northeastern MN and across the Upper and Lower Peninsulas of=20
    Michigan. This will be followed by a strong Arctic cold front that=20
    will dive to the south and east across the region through the day=20
    on Friday. The left exit region of this jet combined with a potent=20
    vort max will support large-scale forcing for ascent across the=20
    Great Lakes in the wake of the lead light snow. With the passage of
    the Arctic front, snow squalls are possible from MI and western NY
    to OH, PA, and WV starting late Thursday night and continuing=20
    through the day on Friday. Some of the stronger showers and squalls
    are looking increasingly likely to spill over the central=20
    Appalachians into parts of the Mid-Atlantic later in the afternoon,
    possibly impacting the evening commute on Friday. Upslope snow in=20
    the central Appalachians should maximize Friday afternoon/evening=20
    as the front moves through.=20

    WPC probabilities for at least 4 inches of snow are low (10-40%)=20
    across the U.P. of Michigan and west of Traverse City. Over western
    NY and NW PA, surface low may move through the region and spur=20
    more widespread snow along/behind the front and as winds turn more=20 northerly, picking up moisture off Lake Ontario. There, WPC=20
    probabilities for at least 4 inches of snow are 20-50%. Finally,=20
    over eastern WV, amounts will likely be the highest in the region=20
    and WPC probabilities for at least 4 inches of snow are >70%,=20
    especially above 2000ft.=20

    In the wake of the Arctic front, a blast of bitterly cold air will
    encompass much of the Northeast heading into the weekend. For more
    details, please reference the Extreme Cold Key Messages in the=20
    link provided below.

    Fracasso


    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!7tsD76lSRVfHX36EwdU0bUH9sv7W5vUQCPqiaIzI-ixFR= Gd4LUnOvsu70q0yzEm9RwTuYw8BtsBuDJVbB7gEJeEI6qI$=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, February 04, 2026 19:42:17
    FOUS11 KWBC 041942
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    242 PM EST Wed Feb 4 2026

    Valid 00Z Thu Feb 05 2026 - 00Z Sun Feb 08 2026


    ...Southern Mid-Atlantic...
    Day 1...

    An area of low pressure riding along a cold front that is tracking
    across the Southeast will bring some wintry precipitation on the
    northern fringe of the precipitation shield along the VA/NC border
    tonight. Rain and a wintry mix will change over to snow, while for
    portions of central and eastern North Carolina, mid-level drying
    with a slow exit of the low level moisture will support a period of
    freezing drizzle, which could accumulate to a few hundredths of an
    inch on untreated surfaces tonight. Both precipitation and
    associated impacts should end within a couple hours of sunrise
    Thursday.=20

    WPC probabilities of 0.01 inches of ice is around 80% for portions
    of North Carolina between Greenville and Fayetteville, and up to
    30% for 0.10 inches of ice. Snow probabilities for an inch of snow
    are between 20-40% along the VA/NC border, and up to 50% along I-81
    southwest of Roanoke, VA.=20



    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-3...

    A warm front will push into the Upper Midwest and western Great=20
    Lakes, aided by a 140kt upper level jet over south central Canada=20
    on Thursday. Light and broad WAA-driven snow is forecast for=20
    northeastern MN and across the Upper and Lower Peninsulas of=20
    Michigan. This will be followed by a strong Arctic cold front that=20
    will dive to the south and east across the region through the day=20
    on Friday. The left exit region of this jet combined with a potent=20
    vort max will support large-scale forcing for ascent across the=20
    Great Lakes in the wake of the lead light snow. With the passage of
    the Arctic front, snow squalls are possible from MI and western NY
    to OH, PA, and WV starting late Thursday night and continuing=20
    through the day on Friday. Some of the stronger showers and squalls
    are looking increasingly likely to spill over the central=20
    Appalachians into parts of the Mid-Atlantic later in the afternoon,
    possibly impacting the evening commute on Friday. Upslope snow in=20
    the central Appalachians should maximize Friday afternoon/evening=20
    as the front moves through.=20

    WPC probabilities for at least 4 inches of snow are low (10-30%)=20
    across the U.P. of Michigan and west of Traverse City. Over western
    NY and NW PA, surface low may move through the region and spur=20
    more widespread snow along/behind the front and as winds turn more=20 northerly, picking up moisture off Lake Ontario. There, WPC=20
    probabilities for at least 4 inches of snow are 20-40%. While there
    is a considerable amount of ice cover on the Great Lakes, just
    under 50% according to the USNIC, there remains enough open water
    on all but Lake Erie to expect there to be at least some
    contribution of lake moisture to the column as the front moves
    through. In addition to upslope into the U.P. of Michigan and
    western New York, higher snow totals can be expected in these
    areas.

    Finally, over eastern WV, amounts will likely be the highest in=20
    the region and WPC probabilities for at least 4 inches of snow are=20
    70%, especially above 2000ft. Considerable upslope flow with
    northwesterly winds orthogonal to the Appalachians should wring out
    the most atmospheric moisture, resulting in the greatest snow
    totals here, hence the highest probabilities.

    In the wake of the Arctic front, a blast of bitterly cold air will
    encompass much of the Northeast heading into the weekend. For more
    details, please reference the Extreme Cold Key Messages in the=20
    link provided below.

    Fracasso/Wegman



    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!-L09wy298h8p0HixTwZRXJh9yemxGI5nIpYl1RfnPrfk3= P4EYhRUXRbBhtoQEcTsBOik16JFMlJIR31mdQRa5gP9iBg$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, February 05, 2026 08:20:01
    FOUS11 KWBC 050819
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    319 AM EST Thu Feb 5 2026

    Valid 12Z Thu Feb 05 2026 - 12Z Sun Feb 08 2026


    ...The Carolinas...=20
    Day 1...

    A deep shortwave trough will track across the northern Gulf and
    then off the Florida coast through this aftn. This will help
    strengthen secondary low pressure off the coast of the Carolinas,
    with some lingering moisture extending back onshore, at least
    through the morning. However, forecast soundings indicate that
    pronounced dry air above the surface will inhibit much in the way
    of precipitation. However, what does fall, will occur in a sub-
    freezing column, leading to a continuation of very light freezing
    rain or freezing drizzle for a few hours after 12Z across the
    eastern Carolinas. This is reflected by WPC probabilities that
    indicate a 10-30% chance (locally 50% chance) of more than 0.01" of
    ice, highest from Cape Fear through the Outer banks.


    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-3...

    A fast moving shortwave diving out of Manitoba will race southeast
    today, reaching the Mid-Atlantic states by Friday morning. This
    lead impulse will be followed almost immediately by a second, more
    strung out, shortwave, with this secondary impulse responsible for
    driving a strong arctic cold front southward beneath it. This
    secondary impulse will help develop a surface wave of low pressure
    across Upstate NY Friday evening, with this low scooting rapidly
    eastward to off the New England coast by the end of D2. The lead
    cold front will trail off this low, with a secondary reinforcing
    surge of arctic air occurring Saturday behind a secondary front.

    Together, these features will result in an extended period of
    moderate ascent, but in an environment with normal to below normal
    PWs on the sharpening NW flow. Although the moisture will be
    modest, the forcing will be sufficient to wring out snowfall across
    the area, although most accumulation will be very light. There may
    be a few exceptions:

    1) Upslope snow into the Central Appalachians. This is expected
    behind the first cold front beginning Friday aftn and then
    intensifying Friday night before waning Saturday evening.
    Intensifying N/NW flow will become quite strong and direct into the
    terrain, with the cooling column providing a deepening DGZ into
    which this ascent will maximize. Although atmospheric moisture is
    modest, this flow will direct at least some Great Lakes enhanced
    moisture to improve the potential for heavy upslope snowfall.
    Initially, Froude numbers Friday and Friday night suggest critical=20
    or blocked flow indicating the heaviest snowfall will be along or=20
    just upwind of the Appalachians crests, but as flow becomes=20
    unblocked on Saturday, more snow may spill over towards the east.=20
    Still, the heaviest accumulations are likely in the higher terrain=20
    and upwind areas, where WPC probabilities for the entire event=20
    suggest a high risk (>70% chance) for at least 8" of snow, with=20
    locally 12+" possible (30% chance).

    The increasing W/NW flow behind the arctic front will also support
    some enhanced lake effect snow (LES), especially in the favored=20
    more N/NW snow belts south of Lake Ontario and Lake Superior. LES
    is not expected to be extremely heavy or prolonged, but WPC
    probabilities indicate a 70-90% chance for at least 4" south of=20
    Lake Ontario, and a 30-50% chance across the eastern U.P. of=20
    Michigan.

    Finally, as a surface low strengthens well offshore and east of=20
    the Mid-Atlantic states, increasing NW flow with a potential=20
    inverted trough will focus some moisture and ascent across eastern=20
    New England from near Portland, ME southward to Cape Cod, MA. The=20 combination of onshore flow and ocean effect snow combined with the
    potential focused inverted trough may enhance snowfall along the=20
    coast. The intensity of this snowfall is still quite uncertain as=20
    most of it is early D3, but these inverted troughs can sometimes=20
    pivot favorably for locally much heavier snowfall. Confidence is=20
    modest at this time range due to wide variations in the models, but
    current WPC probabilities indicate a 50-70% chance for at least 4"
    of accumulation from Cape Ann southward through Cape Cod,=20
    including the Boston metro area.

    Finally, although not expected to be widespread, scattered snow
    squalls are possible along the arctic front as it digs southward
    Friday night into Saturday across the Northeast. Any convective
    snow showers or squalls that develop will contain brief heavy snow
    rates and strong winds, leading to hazardous travel.

    Extremely cold temperatures this weekend have also prompted the
    issuance of Key Messages related to this event. Those are linked
    below.


    Weiss


    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9APqMvp9Avm9tP_63VeqcPXrzpjBn4ND1yCgQrSuQdPno= TECi6gsEfU5JgOPvZFmrGY8NS2tW8VKC-qRNjuSxNNPVTI$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, February 05, 2026 19:18:27
    FOUS11 KWBC 051918
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    218 PM EST Thu Feb 5 2026

    Valid 00Z Fri Feb 06 2026 - 00Z Mon Feb 09 2026


    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-3...

    A deep core low persists north of Hudson Bay through this weekend
    with a focused shortwave trough plunging south from Manitoba
    tonight, crossing the Great Lakes Friday, before deepening as it
    pushes off the Mid-Atlantic Saturday. Rapid surface low development
    is expected well east of New England on Saturday as surface high
    pressure builds over the Upper Midwest, forming an intense pressure
    gradient across the Northeast. A notable surge of Arctic air is
    expected Friday night across the Northeast.

    Extremely cold temperatures this weekend are discussed further in
    Key Messages which are linked below.

    The NW flow behind this shortwave will have ascent, but the
    continental air and mostly ice covered Great Lakes will limit snow
    rates across the Midwest. However, this NW flow will have
    topographic enhancement over the central Appalachians Friday
    afternoon/evening where rates will locally reach 1"/hr. The arctic
    surge over this area is overnight Friday with powerful, potentially
    damaging wind gusts as precip rates decrease. Day 1.5 snow probs
    for >6" are 40-80% from the western edge of MD down the Allegheny
    Highlands into western VA as well as the higher Apps along the
    NC/TN border.

    As the surface low strengthens and the whole system becomes
    develops well off the Mid-Atlantic coast on Saturday, increasing=20
    NW flow over an inverted trough will focus some moisture and=20
    ascent across New England (outside of Maine).=20
    Then on Saturday night there is potential for a focused snow band
    to develop near of over Cape Cod which would have ocean
    enhancements. As of now Day 2 snow probs for >4" are 40-60% for the
    southern shore of Lake Ontario, along the spine of the Green Mtns,
    and generally 30% over eastern Mass down through Long Island.
    Values for >4" then peak around 40% over Cape Cod for Day 2.5.=20

    Finally, although not expected to be widespread, scattered snow
    squalls are possible along the arctic front as it digs southward
    Friday night into Saturday from New York state down through central
    WV. Any convective snow showers or squalls that develop will=20
    contain brief heavy snow rates and strong winds, leading to=20
    hazardous travel.


    ...Northwest...
    Day 3...

    Low pressure pushing northeast into the Gulf of Alaska Saturday
    directs an elevated plume of moisture through the Pacific Northwest
    Saturday afternoon through Sunday. Snow levels on the Cascades=20
    rise to 6000 in WA and 7000ft in OR Saturday afternoon before
    dropping to 5000ft in WA Sunday in moderate precip rates. Day 3
    PWPF for >6" are 40-80% for the Cascade Volcanoes (above key
    mountain passes) and the massif around North Cascades NP.


    Jackson



    ...Cold Key Messages are in effect and linked below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!7KI4dATxiwGQnZk853B_9AzlywkL5ZjkFRAIwG6I2X03r= r6vHEFHnXsemfiTESuFux8NmHZX027MEkGNOGzSd9PYYDg$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, February 06, 2026 08:29:55
    FOUS11 KWBC 060829
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    329 AM EST Fri Feb 6 2026

    Valid 12Z Fri Feb 06 2026 - 12Z Mon Feb 09 2026


    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-2...

    Guidance continues to indicate a period of extreme cold will plague
    the Northeast, Central Appalachians, and Mid-Atlantic states this
    weekend before finally relaxing next week. For this extreme cold,
    Key Messages have been issued which are linked below (Key Messages
    1).

    The driver of this cold will be a sharpening shortwave trough
    digging across the Great Lakes today and then amplifying as it
    pushes off the Mid-Atlantic coast Saturday. This should become a
    closed low south of New England, with the overlap of LFQ diffluence
    in a strengthening downstream jet streak with the strong height
    falls at 500mb leading to a rapidly deepening surface low well
    offshore. While this surface low itself will be too displaced from
    the coast to bring notable weather impacts, its pressure gradient
    will help enhance northerly winds across the region, driving an
    arctic cold front southward, while an inverted trough pivots near
    eastern New England Saturday before moving offshore. This will
    result in three areas of potential heavy snowfall through Saturday.

    1) Central Appalachians: the shortwave itself will cross the
    Central Appalachians Friday morning into the afternoon, pushing the
    strong front southeast beneath it. While some synoptic ascent into
    a modestly moistening column will result in widespread light snow,
    the heaviest accumulations are likely to occur within post-frontal
    upslope ascent. This lift should maximize into the lower portions
    of the deepening DGZ, and as moisture from the Great Lakes gets
    advected southward, this will result in periods of heavy snowfall
    for which the WPC prototype snowband tool suggests will exceed
    1"/hr at times. The heaviest snowfall is expected Friday evening
    through early Saturday morning before the column dries, and WPC
    probabilities indicate a high risk (>70% chance) of at least 6
    inches of snow across the higher terrain of WV, with locally 10+
    inches possible, and at least 4 inches (50-70% chance) extending
    from the Laurel Highlands down into the higher terrain of NC/TN.

    2) Great Lakes: Although ice cover across the Lakes has increased
    dramatically the past few weeks, the intense CAA behind this front
    will still support some lake effect snow (LES) across the open
    waters, especially south of Lake Ontario and Lake Superior D1. The
    intensity of this snowfall should be somewhat muted, but WPC
    probabilities for 4+ inches reach as high as 70-90% south of Lake
    Ontario, with slightly lower probabilities across the eastern U.P.
    and northwest L.P. of MI.

    3) Eastern New England: The most challenging aspect of this
    forecast is what happens across eastern New England, especially
    along the coast from near Portland, ME, through Boston, MA, and
    onto Cape Cod. Strong N/NE winds within the CAA should produce
    ocean enhanced snowfall (OES) especially for Cape Ann and Cape Cod,
    with some enhancement possible anywhere along the coast from Boston
    southward. At the same time, the guidance, while very different in
    its spatial positioning, all show some degree of an inverted trough
    pivoting across the region, with low-level convergence aiding in
    ascent. While there is uncertainty in the placement, and this
    should come into better focus as we get more steadily into the
    high-res windows, there is nearly uniform agreement of this
    occurring, and with some fgen efficiently intersecting the lowering DGZ,
    this will likely result in periods of heavy snowfall. Despite the=20 uncertainty, WPC probabilities have crept upwards to above 50% for
    4+ inches from near Portsmouth, NH south to Boston and Plymouth,
    MA,but some locally higher amounts are probable as reflected by a=20
    lot of spread in the WSE plumes for coastal areas.

    Finally, although not expected to be widespread, scattered snow=20
    squalls are possible along the arctic front as it digs southward=20
    Friday night into Saturday from New York state down through central
    WV and into New England. Any convective snow showers or squalls=20
    that develop will contain brief heavy snow rates and strong winds,=20
    leading to hazardous travel.


    ...Pacific Northwest and Northern Rockies...=20
    Day 3...

    A shortwave emerging from the Northern Pacific will track eastward,
    moving onshore WA/OR Sunday night and then deamplifying as it
    approaches the Northern Rockies by the end of the forecast period.
    Downstream of this impulse, a period of enhanced moisture advection
    will occur, both in response to modest WAA as well as a weak upper
    jet streak pivoting into Canada. Together, this will drive IVT
    onshore in a corridor from OR through the Northern Rockies, which
    has a high probabilities (>80%) of exceeding 250 kg/m/s. The
    duration of this IVT is likely to be limited, and the corresponding
    WAA will surge snow levels up to 5000-6000 ft before falling the
    latter half of D3 (due to CAA behind an accompanying cold front)
    back down to 2000-3000 ft. However, most of the precipitation
    should occur within the warm plume, and this is reflected by WPC
    probabilities indicating a high risk (>70% chance) for at least 4
    inches of snow for the higher terrain of the Cascades and into=20
    parts of the Northern Rockies near Glacier NP, and into the=20
    Sawtooth/Salmon River ranges.

    Weiss



    ...Winter Storm Key Messages are in effect. Please see current=20
    Key Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!7nWiQeLPwPN72vtw9t41hN6JrVIti4KCD6SQD2TX7WWPP= ZZgrW4eB3_Vk4vl1tNvlEpBd3HXuZLoyLL7HuFiyW4fumA$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, February 06, 2026 19:33:41
    FOUS11 KWBC 061933
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    233 PM EST Fri Feb 6 2026

    Valid 00Z Sat Feb 07 2026 - 00Z Tue Feb 10 2026


    ...Great Lakes, Central Appalachians, Northeast, Mid-Atlantic...=20
    Days 1-2...

    Extreme cold and dangerous wind chills overspreads the Northeast=20
    tonight with Key Messages in effect and linked below.

    An upper low currently over James Bay gets sheared southeast over
    the Northeast tonight on account of a strengthening NWly jet below
    a stationary parent low north of Hudson Bay. Surface low pressure
    develops early Saturday outside of the 70W/40N Benchmark with an
    inverted trough extending from that low up through eastern New=20
    England. This movement results in three notable areas of snow.

    1) Central/Southern Appalachians: Ongoing upslope snow for the=20 central/southern Apps through this evening with powerful winds
    overnight behind the cold front. Not much additional snow is
    expected, particularly due to the Great Lakes being mostly ice=20
    covered, but blowing snow is certainly a concern.

    2) Great Lakes: Spotty lake effect snow will continue into Saturday
    for parts of northern MI downwind of open portions of Lake=20
    Superior and Michigan.

    3) Eastern New England: Strong N/NE winds within the CAA should=20
    produce ocean enhanced snowfall (OES) in eastern Mass. At the same
    time, the inverted trough pivots across the region with low- level
    convergence aiding in ascent. Fgen efficiently intersecting the=20
    lowering DGZ will result in narrow corridors of heavy snowfall.=20
    Day 1 snow probs for >4" are 40-70% for southern NH down through
    Rhode Island.

    Snow Squalls: the greatest snow squall threat is this evening over
    Ohio and West Virginia west of the Allegheny Front where high=20
    winds coincide with frontal banding. This area has had the most=20
    notable snow squall parameter values in recent days. Any convective
    snow showers or squalls that develop will contain brief heavy snow
    rates and strong winds, leading to hazardous travel.
    More general snowfall can be expected with the front tonight across
    NY state and the Green Mtns.=20


    ...Pacific Northwest and Northern Rockies...=20
    Days 1-3...

    A shortwave trough axis crosses the Pacific Northwest Saturday/=20
    Saturday night with a second trough crossing late Sunday into
    Monday. Enhanced moisture advection spreads inland ahead of these
    waves with increasing snow over the Cascades and Northern Rockies.=20=20
    Snow levels rise to 6000/7000ft tonight for the WA/OR Cascades with
    levels over WA dropping up to 4000ft Saturday night under height
    falls. Day 1 snow probs for >4" are 40-70% for the North Cascades
    and WA Volcanoes above 6000ft. Day 2 snow probs for >6" are 40-70%
    for the higher WA/OR Cascades and the highest northwest MT ranges.
    Much of the Northwest gets moderate precip with the second wave,
    Day 3 snow probs for >6" are 50-80% for the WA/OR Cascades above
    4000ft and across western MT/central and northern ID and northwest
    WY ranges.


    Jackson



    ...Cold Key Messages are in effect and linked below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!6KUdSlc3x9gxIvJgJ8CClYrdLr-MkgN3h8WhznNitWZ-i= rLKGoqcAEia_Z2pz_5BOuh2Xqg3C0gJPFrlj7Ux-nuxS00$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, February 07, 2026 07:06:46
    FOUS11 KWBC 070706
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    206 AM EST Sat Feb 7 2026

    Valid 12Z Sat Feb 07 2026 - 12Z Tue Feb 10 2026


    ...Northeast & Mid-Atlantic...=20
    Day 1...

    Extreme cold and dangerous wind chills overspread the Northeast=20
    tonight and continue through Sunday with Key Messages in effect=20
    and linked below.

    The combination of an arctic cold front current racing through the
    Ohio Valley/Interior Mid-Atlantic will combine with a strengthening
    low pressure well offshore to produce extremely cold temperatures
    and damaging winds for much of the region, with heavy snow for=20
    parts of the area as well.

    A shortwave driving the cold front southward will help generate
    widespread light snow across New England and Long Island, but total
    snowfall amounts are expected to be rather modest. Despite that,
    briefly heavy snow rates combined with the rapidly increasing winds
    will still result in impacts, especially to travel due to snow-
    covered roads and low visibility. The greatest impacts, and likely
    more substantial snowfall, is expected from far SW Maine, SE New
    Hampshire, and along the eastern Coast of Massachusetts from Cape
    Ann to Cape Cod where low-level convergence, onshore flow and
    resulting ocean effect snow (OES) and an inverted trough will all
    interact to enhance snowfall. There continues to be uncertainty as
    to where the heaviest snowfall will occur. However, intense=20
    snowfall rates of 1-2"/hr are possible (30-60% chance) thanks to=20
    intense ascent into a lowering DGZ within the presence of some=20
    instability. WPC probabilities are moderate (50-70%) for 4+ inches=20
    from the Seacoast of NH through the Boston metro area, with locally
    more than 8 inches possible (10-30% chance) and as reflected by=20
    significant spread amongst the WSE plumes.


    ...Pacific Northwest and Northern Rockies...=20
    Days 1-3...

    Mid-level trough positioned off the Pacific coast will slowly track
    eastward today and Sunday, with the primary trough axis finally
    pushing onshore Sunday night as a shortwave lifts onshore near the
    CA/OR coast. This shortwave will then continue to track east while deamplifying, reaching the northern High Plains by the end of the
    forecast period.

    This trough evolution will be accompanied by a modest subtropical
    jet streak arcing meridionally downstream to provide overlapping
    synoptic ascent. This lift will occur into a moistening column as
    persistent SW flow ahead of the shortwave/trough axis will provide
    a long duration of IVT exceeding 250 kg/m/s, with IVT max
    potentially exceeding 500 kg/m/s (50-60% chance) which will lead to
    two rounds of heavy precipitation extending from Oregon through=20
    the Northern Rockies. Snow levels within the strongest IVT plume
    will be 6000-7000 ft thanks to pronounced WAA, but will steadily
    fall to 3000-4000 ft Monday as a cold front, driven by the
    aforementioned trough, progresses southeast. This will allow for
    heavier and more impactful snow across the Northern Rockies than
    what is anticipated in the Cascades due to lower snow levels. 2-day
    WPC probabilities indicate the heaviest snow is expected in the
    vicinity of Glacier NP in the Northern Rockies where they exceed
    70% for 12+ inches, and locally as much as 2 feet is possible in
    the highest terrain. Elsewhere, WPC probabilities are high (>70%)
    for 8+ inches across the Absarokas and Tetons near Yellowstone NP,
    the Blue Mountains of OR, and across the highest peaks of the WA=20
    and OR Cascades.



    Weiss


    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!4Xa2oHMmm6KfYz7unG9Agh0MhfUQ7fqpY9sRHyH0zmenP= 8OIT453zr1s2_i_RtderGizZjFyR5DPVZVOSXZzX8SPp3g$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, February 07, 2026 19:04:28
    FOUS11 KWBC 071904
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    204 PM EST Sat Feb 7 2026

    Valid 00Z Sun Feb 08 2026 - 00Z Wed Feb 11 2026


    ...Southeast New England...=20
    Day 1...

    Ongoing convergent banding over southeast New England will continue
    to shunt east as it gets further undercut by the Arctic cold front
    which will shift offshore late evening. Remaining snow should taper
    off this evening.


    ...Pacific Northwest and Northern Rockies...=20
    Days 1-2...

    A trough axis pushes across western WA this evening with the
    leading moisture axis maintaining moderate precip rates until the
    overnight when they are shunted south. Snow levels on the WA
    Cascades decrease from 6000ft to 4000ft tonight under height falls.=20
    The primary trough axis pushes onshore the PacNW Sunday evening. This
    wave will then continue to track east while deamplifying, reaching
    the northern High Plains Monday.

    This trough evolution will be accompanied by a modest subtropical
    jet streak arcing meridionally downstream to provide overlapping
    synoptic ascent. This lift will occur into a moistening column as
    persistent SW flow ahead of the shortwave/trough axis will provide
    a long duration of moisture advection with two rounds of heavy=20
    precipitation extending from Oregon through the Northern Rockies.=20
    Day 1 snow probs for >6" are 40-80% for the WA/OR Cascades above
    about 5000ft and over the northern Rockies. Day 2 snow probs for
    6" are similar to Day 1 for the Cascades, but much greater across
    the northern Rockies including 50-90% for the Tetons, Absarokas,
    Sawtooths, Bitterroots, and through Glacier NP. Snow tapers off
    Monday as the trough axis shifts onto the Plains.


    ...Sierra Nevada and Great Basin...=20
    Day 3...

    The next shortwave trough from the Pacific shifts farther south
    than more recent ones, reaching the central/northern CA coast late
    Monday night, crossing the Great Basin Tuesday night. Snow levels
    of 6000 to 7000ft can be expected on the Sierra Nevada with the
    early snow Monday night and 5000 to 6000ft Tuesday as the trough
    axis approaches. Day 3 snow probs for >6" are 50-80% over the
    length of the Sierra Nevada. A welcome sight for skiers and those
    with Sierra hydrology interests.


    Jackson



    ...Extreme Cold Key Messages are in effect and linked below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!-BeRRGW9T0baCl--AvirbLAP2kstK75nNVKBxmBURQ_C9= uocuM5i-gTcobPUFZa9ROYAvgzvZ3UZTtfsdeDhIKBI4LY$=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, February 08, 2026 07:20:09
    FOUS11 KWBC 080719
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    219 AM EST Sun Feb 8 2026

    Valid 12Z Sun Feb 08 2026 - 12Z Wed Feb 11 2026


    ...Pacific Northwest and Northern Rockies...=20
    Days 1-2...

    A surface cold front will be draped NE to SW from Montana through
    Oregon to start the period, lingering from a wave of low pressure
    moving across Canada. As this cold front wavers Sunday, a
    shortwave trough will emerge from the Pacific and cross northeast
    into the Pacific Northwest, reaching the Northern Rockies Monday
    evening while deamplifying and shearing out into the westerlies.
    This will result in a secondary wave of low pressure developing
    along the front which will finally kick the front southeast and out
    of the region.

    Forcing for ascent will intensify as this shortwave lifts
    northeast, as mid-level divergence and heights falls interact atop
    the boundary, and work in tandem with a zonally oriented but
    intensifying jet streak arcing into the Northern Plains. This
    synoptic lift atop the corresponding moisture (via strengthening
    but still modest IVT) will result in a stripe of precipitation,
    with snowfall expected in the higher terrain. Snow levels will be
    falling through the period as the cold front and height falls
    progress E/SE, reaching as low as 3000-4000 ft before precip winds
    down by Tuesday morning. 2-day WPC probabilities indicate a high
    potential (>70% chance) for at least 8 inches in the higher terrain
    of the Cascades, as well as across the Blue Mountains, and much of
    the terrain of the Northern Rockies of ID/western MT/northwest WY.
    Locally 1-2 feet is possible.


    ...Sierra Nevada and Great Basin...=20
    Days 2-3...

    A closed mid-level low west of California will gradually translate
    eastward, potentially coming onshore northern California by the end
    of the forecast period. The progression of this low will result in
    increasing ascent through height falls/mid-level divergence into
    CA. At the same time, a subtropical jet streak will intensify
    downstream of this trough axis, strengthening to 130 kts and
    placing the favorable LFQ diffluent region over CA and into the
    Great Basin, aligning with the strongest height falls. Moisture
    advection will spread onshore beneath modest IVT (40-60% chance of
    at least 250 kg/m/s) but this will be sufficient to spread heavy
    precipitation into the region. With snow levels expected to be
    generally 6000-7000 ft, the heavy snow should be confined to the
    Sierra and higher terrain farther east (Ruby mountains of NV and
    into the Uintas, but at least light snow will spread across much of
    the Great Basin above 6000 ft, rare for what has been an
    exceptionally dry winter so far, and likely welcome for most of the
    region. Current WPC probabilities indicate a high chance (>70%) for
    more than 8 inches in the high Sierra, with locally more than 12
    inches possible (30-50% chance). Farther east, WPC probabilities
    indicate a low risk (30%) for 6+ inches in the Ruby Mountains and
    parts of the Uintas.


    ...Northeast...
    Day 3...

    A clipper-type low will drop out of Ontario and cross Upstate New
    York and New England Tuesday evening/Tuesday night. The clipper
    itself is not impressively strong, but will be preceded by a period
    of moderate WAA which will help expand a shield of snowfall with
    moderate snow rates from NY through central/northern New England.
    As the clipper dives through the area after 00Z Wednesday, it will
    be followed additionally by some upslope ascent into the
    Adirondacks and Greens to enhance snowfall potential. Most of the
    snow should be of moderate intensity and limited duration (6-12
    hours), but where the WAA snow combined with post-system upslope
    snow, a few inches of accumulation is likely. This is reflected by
    WPC probabilities that indicate a 50-70% chance of at least 4
    inches in the Adirondacks and Greens.


    Weiss



    ...Extreme Cold Key Messages are in effect. Please see current Key
    Messages below...

    https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!8eF8W36sZqTxakcMe0UhPFhNgT5PYu0eE845MF0JBX84Q= a-TSjewl7qNUuyG1gEbVE4ah4GKia6xdYgvnsASn-AS6ng$=20



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, February 08, 2026 20:35:10
    FOUS11 KWBC 082034
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    334 PM EST Sun Feb 8 2026

    Valid 00Z Mon Feb 09 2026 - 00Z Thu Feb 12 2026


    ...Pacific Northwest through Northern Rockies...
    Day 1...

    A shortwave trough crosses the Pacific Northwest this evening and
    the northern Rockies Monday. Much of the moisture is ahead of this
    trough axis with moderate to heavy rates stretches from far
    northern CA through OR and western MT. Snow levels are initially
    high, around 7000ft, over northern CA through ID/southern
    MT, with a gradient down to 4000ft just a couple hundred miles
    north. Height falls from the trough axis will lower tonight to
    around 4000ft across the snow zone (3000ft where the 4000ft levels
    currently are). Day 1 snow probs are 50-80% for >6" across the
    Sawtooths through Bitterroots, and all western MT and northwest WY
    ranges. These values are generally 30-70% for the WA/OR Cascades
    above about 5000ft. Ridging behind the trough axis will provide a
    fairly clean cut off for this mountain snow fall by late Monday.


    ...Sierra Nevada to Wyoming...
    Days 2-3...

    A closed mid-level low will approach central California from the
    west on Tuesday before stalling over northern CA through much of
    Wednesday as a reinforcing trough digs around it well offshore.
    Strengthening left exit jet dynamics through this time will enhance
    lift for the onshore flow that rises over the Sierra Nevada. Energy
    sheds east from the upper low Tuesday night bringing much needed
    precip to the Great Basin and central Rockies through midweek.

    Snow levels will be at or just below 7000ft along the Sierra Nevada
    on Tuesday in the onshore flow, dropping to around 6000ft Tuesday
    night under height falls. Great Basin/Rockies snow levels will
    generally remain 6000-7000ft through midweek.

    Day 2 snow probs for >6" are generally 30-60% along the Sierra
    Nevada (and Lassen Peak) for the initial snow on Tuesday. The bulk
    of Sierra snow falls Tuesday night/Wednesday with Day 3 snow probs
    for >12" generally 30-60% between 6500ft and 8000ft (and 80%
    above). High-end advisories are raised for the Sierra Nevada. There
    is risk for localized enhanced snowfall that would warrant targeted
    warnings, particularly if rates can pick up around 7000ft
    elevation. Farther east, Day 3 snow probs for >6" are 30-70% on the
    highest NV ranges (such as Ruby), the highest Uinta, and
    particularly for the Tetons and Wind Rivers.


    ...Northern Great Lakes and Northeast...
    Days 2/3...

    The shortwave trough crossing the Pacific Northwest tonight reaches
    the northern Great Lakes Monday night where it could merge with
    northern stream energy over Ontario and promote decent
    development/warm air advection precip over the northern Great
    Lakes. This would be a wintry mix on the southern end with some
    snow banding potential either over Lake Superior or possibly into
    the eastern U.P. Day 2 snow probs for >4" are 20-50% over the far
    northern L.P. and eastern U.P. while there are 40-70% probs for
    0.01" ice from the WI/MI border ESE across the L.P.

    By Tuesday afternoon the warm air advection plume shifts through
    Upstate NY with the warm nose great enough for a wintry mix which
    should tend toward freezing rain given how cold it has been there
    lately. Day 2.5 snow probs for >4" are 30-70% over the Tug Hill,
    Adirondacks, and Greens while 0.01" ice probs are 30 to 50% for
    northern PA through southern NY and east through greater NYC.

    Coastal low development aids snow banding into eastern Maine on
    Tuesday night into Wednesday. Day 3 snow probs for >4" are 30-50%
    along the entire Maine Coast.


    Jackson



    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, February 09, 2026 07:35:02
    FOUS11 KWBC 090734
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    234 AM EST Mon Feb 9 2026

    Valid 12Z Mon Feb 09 2026 - 12Z Thu Feb 12 2026


    ...Pacific Northwest through Northern Rockies...
    Day 1...

    A shortwave trough crossing the area will be positioned atop the
    interior Northwest to start the period, and then translate rapidly
    eastward through D1. This feature will likely shear out into the
    westerlies as it advects into the High Plains in response to rapid
    ridging building in its wake, but there has been a subtle trend of
    increased amplitude of this feature tonight. This shortwave will
    work effectively with an intensifying upper jet streak to overlap
    mid-level height falls with LFQ diffluence, leading to sufficient
    ascent to produce a wave of low pressure along a cold front south
    of the region.

    Additionally, this jet streak will result in increasing mid-level frontogenesis, especially within the 700-500mb layer, which will
    produce impressive omega directly into the DGZ. Although ascent
    will be temporally modest, cross-sections indicate a high threat
    for CSI within any snow bands that develop, and this could (30-60%
    chance) produce 1-2"/hr snowfall rates. The heaviest snowfall is
    likely in the terrain of the Absarokas and near Yellowstone NP due
    to upslope enhancement, but anywhere across southern MT and
    northern WY could see bands of heavy snowfall which will accumulate
    rapidly despite marginal thermals in the low- levels. The high-res
    guidance has trended upward significantly, as have many of the
    globals, so confidence has increased in significant snowfall
    accumulations, which is now reflected by WPC probabilities that
    indicate a high risk (>70% chance) for at least 4 inches, with more
    than 12 inches possible in the higher terrain including the Lewis
    Range and Tetons.


    ...Sierra Nevada to the Central Rockies...
    Days 2-3...

    A closed mid-level low will approach central California from the
    west on Tuesday before slowly filling into an open, positively
    tilted trough Wednesday as secondary vorticity energy digs towards
    Baja. This slow evolution will result in pronounced S/SW flow
    aloft, which will combine with a strengthening jet streak to spread
    moisture onshore CA and then expand eastward towards the Central
    Rockies by late Wednesday. This prolonged, albeit relatively
    modest, moisture plume/IVT will bring much needed precip to the
    Great Basin and central Rockies through midweek.

    Snow levels will be at or just below 7000ft along the Sierra Nevada
    on Tuesday in the onshore flow, dropping to around 6000ft Tuesday
    night under height falls. Great Basin/Rockies snow levels will
    generally remain 6000-7000ft through midweek.

    2-day snow probabilities from WPC suggest a near certainty (>90%)
    of at least 8 inches across much of the Sierra with locally as much
    as 2 feet possible (30% chance) in the higher Sierra. Additional
    snowfall totals exceeding 8 inches are possible (50-70%) for parts
    of the Uintas, Colorado Rockies, and northern CA ranges.


    ...Northern Great Lakes and Northeast...
    Days 1-3...

    A closed mid-level low will elongate and track from the Northern
    Great Lakes to across New England mid-week, exiting to the Gulf of
    Maine by Thursday morning. This upper feature will be accompanied
    by an extended vorticity lobe on its south side, helping to produce
    strong ascent through height falls/PVA across the region. As this
    develops, pronounced warm air advection (WAA) will develop to its
    south as a surface low /clipper type/ races southeast beneath the
    upper trough. This will produce two rounds of ascent: first with
    the intensifying WAA south of the surface low, and then second with post-clipper CAA/upslope flow.

    While the ascent within the WAA will be impressive, it will also be
    of short duration, generally 6-12 hours, so although snowfall rates
    will likely be intense (50-70% chance of 1+"/hr), the total
    snowfall accumulations will be tempered as reflected by WPC
    probabilities that are around 30% for 4+ inches across the U.P. of
    MI D1, and then 30-70% on D2 for Upstate NY and northern/central
    New England. Despite that, some more significant snowfall
    accumulations are likely across the Tug Hill Plateau, the
    Adirondacks, and the Greens where a combination of CAA for lake
    effect snow (in the Tug Hill) and upslope snow (Adirondacks and
    Greens) will lengthen the duration of accumulating snowfall. In
    these areas, locally more than 8 inches of snow is possible
    (10-30%, highest across the Tug Hill Plateau).

    Finally, as the closed low moves into the Gulf of Maine, a surface
    low will deepen offshore in response. While direct impacts from
    this surface low are not expected to be significant, the guidance
    is hinting at a lingering inverted trough pivoting back across
    coastal Maine Wednesday. These inverted troughs can sometimes lead
    to sneaky-heavy snowfall accumulations, so although current WPC
    probabilities are around 50-70% for 4+ inches of snow, this will
    need to be monitored for any upticks as the event gets closer.


    Weiss


    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, February 09, 2026 19:52:10
    FOUS11 KWBC 091952
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    252 PM EST Mon Feb 9 2026

    Valid 00Z Tue Feb 10 2026 - 00Z Fri Feb 13 2026


    ...Sierra Nevada to the Central Rockies...
    Days 1-3...

    A mid-level low in the northeast Pacific just north of a 150kt jet
    streak this evening will move southeastward then eastward into
    NorCal tomorrow night. This will direct a modest plume of moisture
    into the Sierra with snow levels initially around 7000ft then
    dropping to around 6000ft. Snow could fall at >1"/hr tomorrow night
    in the higher Sierra (>8000ft) then subside through Wednesday. WPC probabilities for at least 8 inches of snow are >50% above 6000ft
    or so with >18" likely (<80%) above 8000ft.

    The system will continue eastward as the upper jet strengthens
    over the Great Basin to central Rockies as the upper trough remains positively-tilted. Moisture will continue to funnel from the sub-
    tropics into the Four Corners region (>90th percentile) on
    southwesterly flow. Snow levels will waver around 6000-7000ft with
    modest amounts expected in an area that has seen very little snow
    this season. WPC probabilities for at least 8 inches of snow are
    50% above 7000ft or so in UT and 8000ft in WY. Snow will linger
    longest over the CO Rockies through Thursday as the moisture plume
    stalls there as a result of a second shortwave trailing the lead
    system, maintaining SW flow through the end of this period. WPC
    probabilities for at least 8 inches of snow are >50% above 10,000ft
    or so in CO.


    ...Northern Great Lakes and Northeast...
    Days 1-3...

    A progressive closed mid-level low will elongate and track from
    the Northern Great Lakes to across New England mid-week,
    translating into the Gulf of Maine on Wednesday. This upper feature
    will be accompanied by an extended vorticity lobe on its south
    side along the occlusion, helping to produce strong ascent through
    height falls/PVA across the region. As this develops, pronounced
    warm air advection (WAA) will develop to its south up and over a
    surface warm front across the Mid-Atlantic. Lead WAA- drive
    precipitation will arrive over northern NY/New England tomorrow
    evening followed by the frontal passage. CAA will ensue with some
    lake effect and upslope snow across the region Wednesday through
    Thursday.

    Quasi-zonal flow will limit precipitation duration, but CAM
    guidance still indicates a window of >1"/hr rates (50-80% chance)
    over the Adirondacks, northern and central VT/NH, and into
    southwest Maine between 21Z Tue and 04Z Wed (from west to east)
    ahead of the occlusion and as it translates into the Gulf of Maine.
    Behind the front, NW flow will support widespread multi-banded
    lake effect snow downwind of all Great Lakes (less from mostly all-
    frozen Erie) that will be enhanced at times from trailing vort
    maxes streaming in from the NW.

    WPC probabilities for at least 4 inches of snow for the event are
    50% over southwestern NY, central NY into the Adirondacks/North
    Country, northern VT/NH and across much of Maine except for far
    northern areas (removed from the higher QPF). Some favored upslope
    areas could see in excess of 8 inches of snow, especially over the
    Tug Hill into the Green Mountains.

    Finally, as the closed low moves into the Gulf of Maine, a new
    surface low down the occlusion will deepen offshore in response.
    While direct impacts from this surface low are not expected to be
    significant, the guidance (e.g., NAMnest, CMCreg) is hinting at a
    lingering inverted trough pivoting back across coastal Maine
    Wednesday afternoon/evening. These inverted troughs can sometimes
    lead to sneaky-heavy snowfall accumulations. WPC probabilities for
    at least 8 inches of snow between Bangor and Eastport are 25-45%
    right now, and may change pending more hi-res guidance.


    Fracasso/Weiss


    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, February 10, 2026 07:16:10
    FOUS11 KWBC 100716
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    216 AM EST Tue Feb 10 2026

    Valid 12Z Tue Feb 10 2026 - 12Z Fri Feb 13 2026


    ...Sierra Nevada to the Central Rockies...
    Days 1-3...

    Mid-level low over the Pacific will gradually pivot eastward
    towards northern CA through Wednesday, lingering across the state
    as it slowly fills. Immediately downstream of this feature, a
    subtropical jet streak will intensify, especially late this evening
    into Wednesday morning, reaching towards 150 kts as it pivots over
    central CA. This upper jet will provide favorable LFQ diffluence
    overlapping the most significant height falls for pronounced
    synoptic ascent, while additionally transporting Pacific moisture
    onshore CA before spreading into the Great Basin and Central
    Rockies. The evolution of this synoptic pattern suggests that SW
    flow downstream of the primary trough axis will support prolonged
    moisture advection, which is reflected by IVT probabilities from
    both the GEFS and ECENS exceeding 90% for 250 kg/m/s for around 24
    today into Wednesday. This moisture will be wrung out by the
    significant deep layer ascent (aided by upslope flow especially
    across the Sierra) to produce heavy snowfall above generally
    6000-7000 ft, with the most intense snowfall rates (2+"/hr
    according to the WPC prototype snowband tool) occurring across the
    Sierra tonight into Wednesday. WPC probabilities across the Sierra
    are high (>70%, 2-day totals) for more than 12 inches in the high
    SIerra, but widespread 8+ inches is likely (>70%) for the breadth
    of the Sierra and into parts of the northern California terrain.

    As the system continues eastward and the upper jet strengthens
    over the Great Basin to central Rockies, moisture will continue to
    funnel from the sub-tropics into the Four Corners region on
    southwesterly flow. Snow levels will waver around 6000-7000ft with
    modest amounts expected in an area that has seen very little snow
    this season. WPC probabilities for at least 8 inches of snow are
    50% above 7000ft or so in UT and 8000ft in WY, highest over the
    Uintas and Wind Rivers/Tetons. Snow will linger longest over the
    CO Rockies through Thursday as the moisture plume stalls there as a
    result of a second shortwave trailing the lead system, maintaining
    SW flow through the end of this period. WPC probabilities for at
    least 8 inches are high for 8+ inches across much of the highest
    terrain of the Colorado Rockies, with a local maximum above 12
    inches expected across the Park Range.


    ...Eastern Great Lakes and Northeast...
    Days 1-2...

    A clipper-type low will dig southeast from Ontario through New
    England today, exiting into the Gulf of Maine late tonight. This
    clipper will be driven primarily by a closed, but weakening, mid-
    level low tracking atop it, with elongated vorticity to its south
    producing additional ascent. As this upper low shifts off New
    England, it will interact with an occlusion well off the coast,
    helping to rapidly deepen a surface low over the Atlantic. This
    synoptic evolution will result in 3 areas of moderate to heavy
    snowfall:

    1) Pronounced warm-air-advection (WAA) developing south of the
    clipper will surge northeast atop a warm front across the Mid-
    Atlantic and into the Northeast. This will create an expanding
    shield of precipitation, and although some light mixed
    rain/snow/freezing rain is expected over the northern Mid-Atlantic,
    much of this precipitation should fall as snow across New England
    and Upstate New York. The snow that occurs will likely be heavy at
    times within a WAA band, likely exceeding 1"/hr (60-90% chance),
    with the short temporal duration limiting the total snowfall.
    Still, impactful snow is likely this evening and tonight spreading
    from west to east.

    2) Post-clipper cold-air-advection (CAA) will become impressive in
    the wake of the low. This will create increasing lake effect snow
    (LES) despite significant ice cover now over the Great Lakes, as
    well as intensifying upslope snow into the terrain of the
    Adirondacks and Greens. Very dry air beneath the subsidence
    inversion will impinge into the DGZ from above during this time, so
    that will act to limit snowfall intensity within the upslope
    regime, but additional accumulations are likely. LES will also be
    somewhat modest, and focused east of Lake Ontario into the Tug Hill
    and then southeast towards the Finger Lakes region, as well as far
    SW NY east of Lake Erie.

    WPC probabilities for 2+ inches of snow are high (>70%) for much
    of northern Upstate NY, as well as central/northern New England.
    However, the more substantial snowfall is likely in the higher
    elevations where WPC probabilities suggest a high risk (>70%) for
    at least 4 inches in the Adirondacks, Greens, and Whites, with
    locally as much as 8 inches possible. For the LES areas, WPC
    probabilities are moderate (50-70%) for least 4 inches. For the
    freezing rain, a swath of moderate probabilities (>50%) exists for
    0.01+" of ice from the Finger Lakes through the Poconos and into
    southern New England and Long Island. Although amounts should be
    less than 0.1"

    3) Finally, as the surface low deepens rapidly offshore and near
    Nova Scotia Wednesday, the guidance continues to suggest a
    lingering inverted trough will pivot near the coast of Maine. Where
    this occurs, additional ascent will be locally impressive, leading
    to the potential for several inches of additional snowfall. These
    inverted troughs can sometimes lead to sneaky-heavy snowfall
    accumulations, so while WPC probabilities are moderate for 6+
    inches (50-70%), locally higher totals are possible as reflected by
    significant spread in the WSE plumes along the coast of Maine.

    Weiss


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, February 10, 2026 19:45:33
    FOUS11 KWBC 101945
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    245 PM EST Tue Feb 10 2026

    Valid 00Z Wed Feb 11 2026 - 00Z Sat Feb 14 2026


    ...Sierra Nevada to the Central/Southern Rockies...
    Days 1-3...

    Closed low just west of NorCal will push eastward tonight as a
    surface cold front moves toward/into the Sierra. A trailing upper
    low to its northwest will take a longer route along its southwest
    side and eventually move into the Southwest/northeastern Mexico
    late in the forecast period. The trough axis will remain
    positively-tilted as the two entities act to slow the overall
    progress of the flow resulting in an unsettled period but bounded
    by two periods of modest to perhaps heavier precipitation. Moisture
    amounts and flux anomalies are modest, but accumulations will be
    aided by favorable upslope SW flow. Snow levels will vary between
    6000-7000ft over the Sierra and snow rates will likely be >1-2"/hr
    at times tonight/early Wednesday per the 12Z CAM guidance. WPC
    probabilities for at least 12 inches of snow are >50% above 6500ft
    or so. Two-day totals may exceed 2ft in the highest elevations.

    Farther downstream, moisture tied back to the subtropics will
    continue to increase over the Great Basin to the central Rockies
    tonight as the upper jet accelerates over the region and PVA
    increases. Snow levels around 6000-7000ft will favor mountain snow
    to areas that have seen very little this season. WPC probabilities
    for at least 8 inches of snow are >50% above 7000ft or so in UT and
    8000ft in WY, highest over the Uintas and Wind Rivers/Tetons, but
    with modest totals overall. Snow will linger longest over the CO
    Rockies through Thursday as the moisture plume stalls due to the
    trailing upper low. WPC probabilities for at least 8 inches of snow
    are >70% above 10,000ft or so in CO. By Friday, as that system
    finally moves over northeastern Mexico, moisture and height falls
    will lead to snow over the southern Rockies (southwestern CO and
    northern NM) as well as into AZ (Mogollon Rim/White Mountains).
    Amounts will be light except for the highest elevations, generally
    above 10,000ft.


    ...Eastern Great Lakes and Northeast...
    Days 1-2...

    A strong clipper-type low will move through New England tonight
    and stretch out to the Gulf of Maine by tomorrow morning. This
    clipper will be driven primarily by a closed, but weakening, mid-
    level low tracking atop it, with elongated vorticity to its south
    producing additional ascent. The elongated vorticity will favor a
    jump in the surface low down the occlusion and into the Gulf of
    Maine by 12Z Wed which will then start to rapidly deepen as it
    pulls away into Atlantic Canada. The storm will come in three
    distinct parts related to winter weather:

    1) Pronounced warm-air-advection (WAA) developing south of the
    clipper this evening will surge northeastward atop a warm front
    across the Mid-Atlantic and into the Northeast. This will create an
    expanding shield of precipitation, and although some light mixed rain/snow/freezing rain is expected over the northern Mid- Atlantic
    into the NYC metro area, much of this precipitation should fall as
    snow across New England (esp north of I-90) and Upstate New York.
    The snow that occurs will likely be heavy at times within a WAA
    band, likely exceeding 1"/hr (60-90% chance per the 12Z HREF), with
    the short temporal duration limiting the total snowfall. Still,
    impactful snow is likely this evening and tonight spreading from
    west to east with the highest totals over the Adirondacks and
    central/northern New England.

    2) Post-clipper cold-air-advection (CAA) will become impressive in
    the wake of the low. This will create increasing lake effect snow
    (LES) despite significant ice cover now over the Great Lakes, as
    well as intensifying upslope snow into the terrain of the
    Adirondacks and Greens. Very dry air beneath the subsidence
    inversion will impinge into the DGZ from above during this time, so
    that will act to limit snowfall intensity within the upslope
    regime, but additional accumulations are likely. LES will also be
    somewhat modest and multi-banded, focused east of Lake Ontario into
    the Tug Hill and then southeast through the Finger Lakes region
    into far SW NY east of mostly frozen Lake Erie (likely aided from
    Lake Huron and/or Georgian Bay).

    WPC probabilities for at least 4 inches of snow are >50% for the
    western Adirondacks as well as central/northern New England and
    much of Maine, especially outside the lower elevations. For the
    higher elevations, WPC probabilities for at least 6 inches of snow
    are >50% over the Greens, Whites, and the Central Highlands in
    Maine with locally as much as 8 inches possible. For the LES areas
    in NY, WPC probabilities are moderate (40-70%) for least 4 inches
    with higher local accumulations. For the freezing rain, a swath of
    moderate probabilities (40-70%) exists for 0.01+" of ice from the
    Finger Lakes/Southern Tier down I-88/81 through the Poconos
    eastward along I-80 through northern NJ and into southern New
    England and perhaps Long Island. Amounts should be less than 0.10"
    but any freezing rain can be hazardous to travel, especially
    overnight.

    3) Finally, as the surface low deepens rapidly offshore and near
    Nova Scotia Wednesday, the guidance continues to suggest a
    lingering inverted trough that will pivot near the coast of eastern
    Maine. Where this occurs, additional ascent will be locally
    impressive, leading to the potential for several inches of
    additional snowfall. These inverted troughs can sometimes lead to
    sneaky-heavy snowfall accumulations, but WPC probabilities for at
    least 8 inches of snow are moderate (40-70%) around Eastport.
    Locally higher totals are possible as reflected in some rather
    robust 12Z CAM members along the coast of Maine.

    The probability of significant icing across the CONUS is less than
    10 percent.


    Fracasso/Weiss


    $$

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