ACUS01 KWNS 221251
SWODY1
SPC AC 221250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Fri Aug 22 2025

Valid 221300Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS TO THE UPPER MIDWEST AS WELL AS ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms are possible from parts of
the central and northern High Plains to the Upper Midwest, and
across parts of Arizona.

...Upper Midwest/Upper Great Lakes...
Upper trough amplification will continue to occur over
Manitoba/northern Ontario through tonight, with consequential height
falls over the upper Great Lakes. A cold front will continue to
advance southeastward regionally, with a semi-moist air mass
preceding it. A consequential factor for portions of the region will
be an MCS centered across far eastern South Dakota early this
morning, which will continue to disturb the frontal zone and nearby
warm sector for the first part of the day. This may especially be
the case across southern Minnesota and vicinity.

But on the periphery of the MCS-influenced corridor, potential
severe storm development could occur by late afternoon, perhaps most
likely across eastern Nebraska and western Iowa, but also across
northwest Wisconsin/Upper Michigan where vertical shear will be
stronger but with more modest buoyancy. Hail and damaging winds
would be possible in both scenarios, but likely on a relatively
isolated basis.

...Wyoming/Colorado and central High Plains...
A subtle ridge-peripheral disturbance noted in water vapor imagery,
along with strong surface heating, should aid thunderstorm
development initially across Wyoming/Colorado. This activity should
propagate east-southeast toward lower elevations in the presence of
moist low-level upslope flow. Hail and wind are possible with this
activity, especially within a corridor across interior/southeast
Wyoming into northeast/east-central Colorado.

...Arizona...
The upper high will shift west-northwestward through tonight,
maintaining and potentially strengthening easterly mid-level winds
across southern Arizona, in addition to the possibility of slightly
cooler (degree or two C) mid-level temperatures. Lingering morning
cloud cover should gradually abate into the afternoon, with a very hot/residually moist boundary layer contributing to widely scattered thunderstorm development, initially over higher terrain.
West/southwestward spreading storms will pose the potential for
strong wind gusts/blowing dust onto the desert floor.

..Guyer/Kerr.. 08/22/2025

$$

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ACUS01 KWNS 221632
SWODY1
SPC AC 221630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Fri Aug 22 2025

Valid 221630Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS TO THE UPPER MIDWEST/GREAT
LAKES...AND PORTIONS OF SOUTHERN/CENTRAL ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms may occur today from parts of
the northern and central High Plains to the Upper Midwest/Great
Lakes, and separately across parts of Arizona. Damaging winds and
occasional hail should be the main threats.

...Synopsis...
A mid/upper-level trough/low centered over Manitoba late this
morning will move east-southeastward across Ontario and the Upper
Midwest/Great Lakes through the period. At the surface, a weak cold
front is forecast to develop southeastward across the
northern/central High Plains and Upper Midwest this afternoon and
evening. This boundary should serve as a focus for additional
thunderstorm development later today, some of which could become
strong to severe. A mid/upper-level anticyclone will remain anchored
over the Four Corners region today, with modest easterly mid-level
flow persisting over parts of AZ.

...Northern/Central High Plains to the Upper Midwest/Great Lakes...
A broad zone of isolated strong to severe thunderstorm potential
remains evident today, generally along/near a convectively
reinforced cold front extending from the central High Plains
east-northeastward to the Upper Midwest/Great Lakes. Within this
broad zone, three somewhat separate regimes of severe potential are
apparent.

Thunderstorms have recently developed across parts of
central/eastern MN and far northwest WI ahead of a remnant
MCV/subtle mid-level shortwave trough. The airmass downstream from
this activity across northern WI into the U.P. of MI is only weakly
unstable, with scattered to broken mid/upper-level clouds present.
Stronger mid-level flow is also forecast to generally lag behind the
surface cold front across this region. Still, a small cluster or two
may eventually evolve from the ongoing convection in MN, and spread
eastward through the afternoon/early evening. Occasional damaging
winds should be the main threat, but some hail may also occur with
the stronger cores given cool mid-level temperatures and around
25-35 kt of deep-layer shear aiding updraft organization. Considered
adding a Slight Risk for severe/damaging winds across parts of
northern WI and vicinity, but confidence in more robust
destabilization occurring remains low. Trends will be monitored for
a possible upgrade at 20Z, if needed.

Outflow from earlier thunderstorms continues to advance southward
across parts of eastern NE and northwest IA per recent surface
observations and visible satellite imagery. The effect of this
outflow surge on additional thunderstorm development this afternoon
remains unclear, as the primary cold front lags the outflow by a
considerable extent. Some guidance suggests that a couple of
supercells or perhaps a small cluster may develop over far southeast
SD into eastern NE and western IA later today as the airmass across
these areas gradually destabilizes. At least an isolated risk for
severe hail and damaging winds will exist if this occurs. But, the
overall severe threat remains too uncertain for a categorical
upgrade with this outlook update.

Farther west, a subtle mid-level ridge-peripheral disturbance noted
in water vapor imagery across southern WY and northwest CO, along
with strong daytime heating, should aid thunderstorm development
initially across the higher terrain of the central Rockies later
this afternoon. This activity should propagate east-southeastward
toward lower elevations in the presence of moist, post-frontal
low-level upslope flow. Isolated severe hail and winds are possible
with this activity, especially within a corridor across
interior/southeast WY into northeast/east-central CO.

...Arizona...
A fair amount of convective cloud debris is present today across
parts of AZ per recent visible satellite imagery. This may tend to
delay diurnal heating and related steepening of low-level lapse
rates to some extent. But, eventual airmass recovery is still
expected by late afternoon/early evening, with seasonably moist
low-levels still noted on the 12Z observed PHX sounding.
Thunderstorms should once again form initially along the higher
terrain of the Mogollon Rim and southeastern AZ before spreading west-southwestward across the lower elevations of central/southern
AZ through the evening. Sufficient instability, a very well-mixed
boundary layer, and modest easterly mid-level flow should all
support an isolated threat for severe/damaging winds with this
activity.

..Gleason/Moore.. 08/22/2025

$$

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ACUS01 KWNS 222003
SWODY1
SPC AC 222001

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Fri Aug 22 2025

Valid 222000Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS TO THE UPPER MIDWEST/GREAT
LAKES...AND PORTIONS OF SOUTHERN/CENTRAL ARIZONA...

...SUMMARY...
Strong to locally severe thunderstorms may occur today from parts of
the northern and central High Plains to the Upper Midwest/Great
Lakes, and separately across parts of Arizona. Damaging winds and
occasional hail should be the main threats.

...20z Update...
Minor adjustments were made to remove thunder chances and the
Marginal Risk behind ongoing convection from Iowa to Wisconsin.
Otherwise, the forecast remains on track. See previous discussion
below for more information.

..Thornton.. 08/22/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 22 2025/

...Synopsis...
A mid/upper-level trough/low centered over Manitoba late this
morning will move east-southeastward across Ontario and the Upper
Midwest/Great Lakes through the period. At the surface, a weak cold
front is forecast to develop southeastward across the
northern/central High Plains and Upper Midwest this afternoon and
evening. This boundary should serve as a focus for additional
thunderstorm development later today, some of which could become
strong to severe. A mid/upper-level anticyclone will remain anchored
over the Four Corners region today, with modest easterly mid-level
flow persisting over parts of AZ.

...Northern/Central High Plains to the Upper Midwest/Great Lakes...
A broad zone of isolated strong to severe thunderstorm potential
remains evident today, generally along/near a convectively
reinforced cold front extending from the central High Plains
east-northeastward to the Upper Midwest/Great Lakes. Within this
broad zone, three somewhat separate regimes of severe potential are
apparent.

Thunderstorms have recently developed across parts of
central/eastern MN and far northwest WI ahead of a remnant
MCV/subtle mid-level shortwave trough. The airmass downstream from
this activity across northern WI into the U.P. of MI is only weakly
unstable, with scattered to broken mid/upper-level clouds present.
Stronger mid-level flow is also forecast to generally lag behind the
surface cold front across this region. Still, a small cluster or two
may eventually evolve from the ongoing convection in MN, and spread
eastward through the afternoon/early evening. Occasional damaging
winds should be the main threat, but some hail may also occur with
the stronger cores given cool mid-level temperatures and around
25-35 kt of deep-layer shear aiding updraft organization. Considered
adding a Slight Risk for severe/damaging winds across parts of
northern WI and vicinity, but confidence in more robust
destabilization occurring remains low. Trends will be monitored for
a possible upgrade at 20Z, if needed.

Outflow from earlier thunderstorms continues to advance southward
across parts of eastern NE and northwest IA per recent surface
observations and visible satellite imagery. The effect of this
outflow surge on additional thunderstorm development this afternoon
remains unclear, as the primary cold front lags the outflow by a
considerable extent. Some guidance suggests that a couple of
supercells or perhaps a small cluster may develop over far southeast
SD into eastern NE and western IA later today as the airmass across
these areas gradually destabilizes. At least an isolated risk for
severe hail and damaging winds will exist if this occurs. But, the
overall severe threat remains too uncertain for a categorical
upgrade with this outlook update.

Farther west, a subtle mid-level ridge-peripheral disturbance noted
in water vapor imagery across southern WY and northwest CO, along
with strong daytime heating, should aid thunderstorm development
initially across the higher terrain of the central Rockies later
this afternoon. This activity should propagate east-southeastward
toward lower elevations in the presence of moist, post-frontal
low-level upslope flow. Isolated severe hail and winds are possible
with this activity, especially within a corridor across
interior/southeast WY into northeast/east-central CO.

...Arizona...
A fair amount of convective cloud debris is present today across
parts of AZ per recent visible satellite imagery. This may tend to
delay diurnal heating and related steepening of low-level lapse
rates to some extent. But, eventual airmass recovery is still
expected by late afternoon/early evening, with seasonably moist
low-levels still noted on the 12Z observed PHX sounding.
Thunderstorms should once again form initially along the higher
terrain of the Mogollon Rim and southeastern AZ before spreading west-southwestward across the lower elevations of central/southern
AZ through the evening. Sufficient instability, a very well-mixed
boundary layer, and modest easterly mid-level flow should all
support an isolated threat for severe/damaging winds with this
activity.

$$

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ACUS01 KWNS 230059
SWODY1
SPC AC 230057

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0757 PM CDT Fri Aug 22 2025

Valid 230100Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE UPPER MIDWEST...

...SUMMARY...
Isolated strong to locally severe thunderstorms may occur this
evening and into tonight from parts of the northern and central High
Plains to the Upper Midwest/Great Lakes, and separately across parts
of Arizona. Damaging winds and occasional hail should be the main
threats.

...Upper Midwest...
A cluster of storms across northern Wisconsin and the UP has now
moved into Canada and is weakening on the eastern periphery of the
better instability. In the wake of this activity, a few storms have
developed along a cold front moving through northern Minnesota with
a few isolated showers/storms developing ahead of it. Have adjusted
the thunder line west to account for these storms and will keep the
marginal across southeast Minnesota and northwest Wisconsin where
instability remains. This threat will likely only continue for a few
more hours before a cooling boundary layer stabilizes the area.

...Central Plains into the central High Plains...
The earlier cluster of storms across eastern Nebraska moved south
and weakened as it moved into a more stable airmass across southern
Nebraska. However, an additional storm developed across east-central
Nebraska where 2000 J/kg MLCAPE is present. This threat may remain
for a few more hours before eventual nocturnal stabilization ends
the threat.

Storms across Wyoming and northeast Colorado have been relatively
weak thus far. However, as heights continue to fall across the
region, expect these storms to maintain with additional storm
development also possible. Weak to moderate instability with 30 to
35 knots of shear will support the potential for isolated strong
storms capable of large hail or severe wind gusts this evening and
into the early overnight hours.

..Bentley.. 08/23/2025

$$

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ACUS01 KWNS 230546
SWODY1
SPC AC 230544

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Sat Aug 23 2025

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL HIGH PLAINS....

...SUMMARY...
Strong to isolated severe storms are possible in the central High
Plains today.

...Synopsis...
A mid-level trough will amplify across the Great Lakes today with
strengthening mid-level flow across the Northern Plains. Surface
high pressure building into the northern Plains this morning will
advance into the central Plains by this afternoon and push a cold
front south across the Plains and Upper Midwest. Farther east, a
cold front, associated with the mid-level trough across the northern
Great Lakes, will move across the Great Lakes and Ohio Valley.

...Central High Plains...
Upslope flow in the wake of the cold front across the central High
Plains may provide an environment favorable for a few isolated
strong to severe storms this afternoon/evening. Terrain driven
storms are anticipated across much of the central Rockies. A few
storms are expected to move off of the higher terrain, and with
support from low-level upslope flow, maintain themselves along the
Front Range as they move south. Steep mid-level lapse rates and
around 35 to 40 knots of mid-level flow will support the potential
for isolated supercell structures capable of isolated large hail and
severe wind gusts. Storm motions around 350 degrees and storm
formation expected along the mountains and immediate foothills will
result in a very narrow area of risk along the Front Range from
southeast Wyoming to central Colorado. Slightly stronger instability
across southeast Colorado and the potential for some clustering of
storms supports a slightly wider marginal extending into this
region.

...Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes this afternoon. Warm 700mb temperatures in the presence of only low 60s dewpoints will limit
overall buoyancy and updraft strength. Therefore, no severe
thunderstorms are expected.

..Bentley/Weinman.. 08/23/2025

$$

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ACUS01 KWNS 231247
SWODY1
SPC AC 231246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Aug 23 2025

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FRONT RANGE/CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe storms are possible near the Colorado/Wyoming Front
Range and central High Plains this afternoon and evening.

...Front Range/Central High Plains...
Multiple subtle upper ridge-peripheral impulses and a belt of
moderately strong northwesterly winds aloft will influence the
region as low-level upslope flow increases late today within the
post-frontal environment. At least widely scattered thunderstorm
development is expected initially over the mountains, with
subsequent intensification as storms develop east-southeastward into
a moderately unstable air mass, with buoyancy maximized
near/immediately east of the urban corridor/I-25. Steep mid-level
lapse rates and 40+ kt effective shear will support the possibility
of isolated supercells capable of large hail and some locally
stronger wind gusts through early evening.

...Midwest/Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes/Midwest this afternoon.
Warm 700mb temperatures in the presence of only low 60s dewpoints
will limit overall buoyancy and updraft strength, likely keeping
severe-storm potential minimal.

..Guyer/Kerr.. 08/23/2025

$$

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ACUS01 KWNS 231624
SWODY1
SPC AC 231622

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Sat Aug 23 2025

Valid 231630Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE COLORADO/WYOMING FRONT RANGE AND ADJACENT CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms appear possible near the
Colorado/Wyoming Front Range and central High Plains this afternoon
and evening.

...Front Range/Central High Plains...
A mid/upper-level anticyclone centered over the Southwest and Four
Corners regions will move little today, with ridging extending
northward across much of the Great Basin and Northwest. Modestly
enhanced northwesterly mid-level flow will exist today across the
central Rockies and adjacent High Plains. A moist post-frontal
airmass will remain in place across these areas, with surface
dewpoints generally in the mid to upper 50s. Low cloud cover remains
prevalent across the central High Plains late this morning, which
should continue to hinder destabilization to some extent. Even so,
gradual thunderstorm development should eventually occur over the
higher terrain by late afternoon as persistent low-level upslope
flow aids parcels in reaching their LFCs. This activity should
spread generally south-southeastward through the evening along/near
the I-25 corridor, while posing an isolated threat for mainly hail
due to a combination of modestly steepened lapse rates aloft,
sufficient deep-layer shear, and weak to moderate MLCAPE. Occasional strong/gusty winds may also occur.

...Great Lakes/Midwest...
Isolated thunderstorms should develop along a cold front this
afternoon as it advances eastward across part of the Great
Lakes/Midwest. Warm low/mid-level temperatures in the presence of
generally low/mid 60s surface dewpoints should limit buoyancy and
updraft strength, likely keeping the overall severe potential low.

..Gleason/Moore.. 08/23/2025

$$

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ACUS01 KWNS 231930
SWODY1
SPC AC 231928

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 PM CDT Sat Aug 23 2025

Valid 232000Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE COLORADO/WYOMING FRONT RANGE AND ADJACENT CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms appear possible near the
Colorado/Wyoming Front Range and central High Plains this afternoon
and evening.

...20z Update...
No changes are needed to the current D1 Convective Outlook. See
previous discussion below for more information.

..Thornton.. 08/23/2025

.PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Aug 23 2025/

...Front Range/Central High Plains...
A mid/upper-level anticyclone centered over the Southwest and Four
Corners regions will move little today, with ridging extending
northward across much of the Great Basin and Northwest. Modestly
enhanced northwesterly mid-level flow will exist today across the
central Rockies and adjacent High Plains. A moist post-frontal
airmass will remain in place across these areas, with surface
dewpoints generally in the mid to upper 50s. Low cloud cover remains
prevalent across the central High Plains late this morning, which
should continue to hinder destabilization to some extent. Even so,
gradual thunderstorm development should eventually occur over the
higher terrain by late afternoon as persistent low-level upslope
flow aids parcels in reaching their LFCs. This activity should
spread generally south-southeastward through the evening along/near
the I-25 corridor, while posing an isolated threat for mainly hail
due to a combination of modestly steepened lapse rates aloft,
sufficient deep-layer shear, and weak to moderate MLCAPE. Occasional strong/gusty winds may also occur.

...Great Lakes/Midwest...
Isolated thunderstorms should develop along a cold front this
afternoon as it advances eastward across part of the Great
Lakes/Midwest. Warm low/mid-level temperatures in the presence of
generally low/mid 60s surface dewpoints should limit buoyancy and
updraft strength, likely keeping the overall severe potential low.

$$

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ACUS01 KWNS 240041
SWODY1
SPC AC 240040

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 PM CDT Sat Aug 23 2025

Valid 240100Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG THE
CENTRAL ROCKIES FRONT RANGE...

...SUMMARY...
Isolated severe thunderstorms remain possible near the
Colorado/Wyoming Front Range and central High Plains this evening.

...01z Update...

Great Basin upper ridge is gradually building north across the
Interior West early this evening. As a result, northwesterly flow
remains firmly established across eastern WY/CO. Scattered
convection has developed beneath this feature with the eastern-most thunderstorms noted along the CO Front Range. Latest diagnostic data
continues to depict a narrow corridor of modest instability along
the Front Range from southeast WY into northeast NM. A few robust
thunderstorms are noted along this corridor but MRMS data suggests
any hail with this activity is likely marginally severe at best.
Will maintain MRGL Risk for isolated-scattered thunderstorms this
evening as cloud-layer shear is more than strong enough for
organized updrafts.

Southeast Lower Michigan: Scattered thunderstorms have developed
along the cold front across southern ON into southeast MI. While
gusty winds, and perhaps some marginally severe hail, may be noted
with these storms for the next hour or so, this activity will
quickly shift into ON. Severe probabilities will not be introduced
for these reasons.

..Darrow.. 08/24/2025

$$

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ACUS01 KWNS 240542
SWODY1
SPC AC 240540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Sun Aug 24 2025

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NEW YORK/PENNSYLVANIA AND FROM EASTERN COLORADO TO WESTERN
OKLAHOMA...

...SUMMARY...
A few storms may reach severe thresholds from eastern Colorado into
western Oklahoma this afternoon and evening. Scattered strong-severe
storms are possible across portions of Pennsylvania and New York.
Hail or wind are the expected risks.

...NY/PA...

Early-morning satellite imagery depicts a strong upper trough over
ON/Great Lakes, shifting east-southeast in line with latest model
guidance. Associated surface front is forecast to advance into
western NY/PA by early afternoon before shifting into central
portions of these states by 25/00z. Modest boundary-layer heating is
expected to aid destabilization ahead of the front and convective
temperatures are expected to be breached around 20-21z; although,
deep-layer lapse rates are not expected to be particularly steep
(0-6km values around 6.5 C/km). While CAMs support this with
scattered frontal convection developing around mid afternoon. This
activity could generate locally strong winds, and perhaps some hail.
Main risk will be during the mid afternoon into early evening before
the boundary layer cools after sunset.

...Eastern CO to western OK...

Eastern periphery of Great Basin high will flatten as northwesterly
flow becomes firmly established along the back side of Great
Lakes/OH Valley trough. At the surface, pronounced surface
anticyclone will settle into the northern Plains, ultimately forcing
the leading edge of more continental air into the southern Plains by
the end of the period. Net take is a corridor of low-level warm
advection will become established from southern WY into western OK -
coincident with northwest-southeast frontal orientation. It appears
a few weak disturbances will top the ridge and dig southeast toward
the southern Plains. Each of these features should encourage a
response in the LLJ, which will aid convective development. Elevated
convection may be ongoing at the start of the period across western
NE into northwest KS. A substantial cluster/MCS should propagate
southeast with renewed development later in the period. Rain-cooled
boundary layer will ensure stronger heating is focused across
southeast CO into western OK. Primary concern for isolated severe
will be near this zone of stronger heating/instability. Hail and
wind may accompany this more robust convection.

..Darrow/Weinman.. 08/24/2025

$$

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ACUS01 KWNS 241125
SWODY1
SPC AC 241124

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0624 AM CDT Sun Aug 24 2025

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND NORTHEAST...

...SUMMARY...
A few severe storms are expected this afternoon and evening across
the south-central High Plains spanning eastern Colorado into western
Oklahoma. Scattered strong to severe storms are also possible across
portions of Pennsylvania and New York.

...South-central High Plains..
Within an amplified upper flow regime, a moderately strong belt of northwesterly winds aloft will exist over the region, with one or
more low-amplitude ridge-peripheral disturbances expected to pivot
eastward later today over the central Rockies. A pronounced surface
anticyclone will settle into the northern Plains, forcing the
leading edge of more continental air into the southern Plains by the
end of the period. A corridor of low-level warm advection will
become established from southern Wyoming into western Oklahoma
coincident with the northwest/southeast-oriented front.

Widely scattered generally non-severe elevated storms will probably
persist this morning across western Kansas, with some potential that
the storms may help focus some renewed/increasing convective
potential later today from southwest Kansas into western
Oklahoma/eastern Texas Panhandle. Aided by increasing low-level
upslope flow, other potentially severe storms are expected to
develop across the Colorado Front Range vicinity by late afternoon
and drift southeastward through early/mid-evening. A couple of
supercells will initially be possible, before storms tend to cluster
by evening. Large hail and damaging winds are the primary concerns
regionally, although current thinking is that overall potential
should remain relatively isolated.

...Northeast including New York/Pennsylvania...
A prominent upper-level trough over Ontario/Quebec and Great Lakes
will shift eastward today. An associated surface front is forecast
to advance into western portions of New York/Pennsylvania by early
afternoon. Modest boundary-layer heating is expected to aid
destabilization ahead of the front and convective temperatures
should be breached by around 20-21z; although, deep-layer lapse
rates are not expected to be particularly steep (0-6 km values
around 6.5 C/km). These storms could generate locally strong winds,
and perhaps some hail, with the main risk from mid-afternoon into
early evening.

..Guyer/Kerr.. 08/24/2025

$$

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ACUS01 KWNS 241132
SWODY1
SPC AC 241131

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0631 AM CDT Sun Aug 24 2025

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND NORTHEAST...

...SUMMARY...
A few severe storms are expected this afternoon and evening across
the south-central High Plains spanning eastern Colorado into western
Oklahoma. Scattered strong to severe storms are also possible across
portions of Pennsylvania and New York.

...South-central High Plains..
Within an amplified upper flow regime, a moderately strong belt of northwesterly winds aloft will exist over the region, with one or
more low-amplitude ridge-peripheral disturbances expected to pivot
eastward later today over the central Rockies. A pronounced surface
anticyclone will settle into the northern Plains, forcing the
leading edge of more continental air into the southern Plains by the
end of the period. A corridor of low-level warm advection will
become established from southern Wyoming into western Oklahoma
coincident with the northwest/southeast-oriented front.

Widely scattered generally non-severe elevated storms will probably
persist this morning across western Kansas, with some potential that
the storms may help focus some renewed/increasing convective
potential later today from southwest Kansas into western
Oklahoma/eastern Texas Panhandle. Aided by increasing low-level
upslope flow, other potentially severe storms are expected to
develop across the Colorado Front Range vicinity by late afternoon
and drift southeastward through early/mid-evening. A couple of
supercells will initially be possible, before storms tend to cluster
by evening. Large hail and damaging winds are the primary concerns
regionally, although current thinking is that overall potential
should remain relatively isolated.

...Northeast including New York/Pennsylvania...
A prominent upper-level trough over Ontario/Quebec and Great Lakes
will shift eastward today. An associated surface front is forecast
to advance into western portions of New York/Pennsylvania by early
afternoon. Modest boundary-layer heating is expected to aid
destabilization ahead of the front and convective temperatures
should be breached by around 20-21z; although, deep-layer lapse
rates are not expected to be particularly steep (0-6 km values
around 6.5 C/km). These storms could generate locally strong winds,
and perhaps some hail, with the main risk from mid-afternoon into
early evening.

..Guyer/Kerr.. 08/24/2025

$$

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ACUS01 KWNS 241632
SWODY1
SPC AC 241630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Aug 24 2025

Valid 241630Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL HIGH PLAINS...AND PORTIONS OF NEW YORK AND
PENNSYLVANIA...

...SUMMARY...
A few severe thunderstorms should develop this afternoon and evening
across the southern/central High Plains spanning from eastern
Colorado into western Oklahoma. Scattered strong to severe
thunderstorms are also possible across portions of Pennsylvania and
New York.

...Southern/Central High Plains...
Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This
activity has generally remained sub-severe, but the stronger cores
could be capable of producing occasional hail as they track
southeastward this afternoon given the presence of sufficient MUCAPE
and deep-layer shear. Modestly enhanced mid-level flow is expected
to remain over parts of the central into southern Plains today,
generally from eastern WY/CO into western KS/OK and vicinity,
between a mid/upper-level anticyclone over the Southwest and
mid/upper-level troughing across the Upper Midwest. A surface front
extends from northern CO into western KS. This boundary, along with
outflow from ongoing convection, may serve as foci for robust
thunderstorm development later today.

There is still a fair amount of uncertainty regarding convective
development and evolution this afternoon/evening across the
southern/central High Plains given weak forcing aloft. Modest
low-level upslope flow and orographic effects should encourage at
least isolated thunderstorms to initially develop over the higher
terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The
front/outflow boundary draped from northeast CO into southwest KS
could also serve as a forcing mechanism to aid parcels in reaching
their LFCs. The environment along/south of the front should become
moderately unstable with continued daytime heating, with greater
low-level moisture present across western KS into the OK/TX
Panhandles and western OK.

Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally
enhance 0-1 km SRH. It appears possible that a supercell or two
could develop near the front later today and track
south-southeastward in a favorable northwesterly mid-level flow
regime. Isolated large hail would probably be the main threat if a
supercell can be sustained, with perhaps a tornado also possible
where low-level flow can remain backed to southeasterly near the
front. Some guidance suggests a cluster or two may eventually emerge
this evening across eastern CO and/or southwest KS, but this
potential remains highly uncertain. Mesoscale trends will be
monitored for a zone of more focused severe potential and possible
outlook upgrade.

...New York/Pennsylvania...
An amplified upper trough/low over Ontario and extending southward
into the Great Lakes/Midwest is forecast to gradually shift eastward
today. A related surface cold front will also advance
east-southeastward through the period across parts of the Northeast
and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly
moist low-level airmass ahead of the front will promote weak to
locally moderate instability this afternoon, especially across parts
of PA/NY. Current expectations are for thunderstorms to develop
along/near the front through the afternoon across western PA/NY.
While mid-level lapse rates are forecast to remain poor, which will
likely limit updraft strength, sufficient deep-layer shear should be
present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and
perhaps marginally severe hail as they spread eastward across
central PA and central/northern NY through early evening. This
activity should weaken with eastward extent as it encounters a less
unstable airmass.

..Gleason/Moore.. 08/24/2025

$$

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ACUS01 KWNS 242000
SWODY1
SPC AC 241959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun Aug 24 2025

Valid 242000Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO
INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA
PANHANDLE...

...SUMMARY...
A few severe thunderstorms are expected this afternoon and evening
across the southern/central High Plains spanning from eastern
Colorado into western Oklahoma. Scattered strong to severe
thunderstorms are also possible across portions of Pennsylvania and
New York.

...20z Update...
An upgrade to Slight was made with this update in eastern
Colorado/western Kansas. Thermodynamics and shear profiles are
favorable for supercell development. Recent development on radar
suggests attempts are ongoing across portions of eastern Colorado
near the Palmer Divide and near Colorado Springs. Any more discrete
supercells that can be maintained will pose a risk for large hail,
and as such a 15% was added with this update. See MCD#2009 for more information.

..Thornton.. 08/24/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/

...Southern/Central High Plains...
Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This
activity has generally remained sub-severe, but the stronger cores
could be capable of producing occasional hail as they track
southeastward this afternoon given the presence of sufficient MUCAPE
and deep-layer shear. Modestly enhanced mid-level flow is expected
to remain over parts of the central into southern Plains today,
generally from eastern WY/CO into western KS/OK and vicinity,
between a mid/upper-level anticyclone over the Southwest and
mid/upper-level troughing across the Upper Midwest. A surface front
extends from northern CO into western KS. This boundary, along with
outflow from ongoing convection, may serve as foci for robust
thunderstorm development later today.

There is still a fair amount of uncertainty regarding convective
development and evolution this afternoon/evening across the
southern/central High Plains given weak forcing aloft. Modest
low-level upslope flow and orographic effects should encourage at
least isolated thunderstorms to initially develop over the higher
terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The
front/outflow boundary draped from northeast CO into southwest KS
could also serve as a forcing mechanism to aid parcels in reaching
their LFCs. The environment along/south of the front should become
moderately unstable with continued daytime heating, with greater
low-level moisture present across western KS into the OK/TX
Panhandles and western OK.

Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally
enhance 0-1 km SRH. It appears possible that a supercell or two
could develop near the front later today and track
south-southeastward in a favorable northwesterly mid-level flow
regime. Isolated large hail would probably be the main threat if a
supercell can be sustained, with perhaps a tornado also possible
where low-level flow can remain backed to southeasterly near the
front. Some guidance suggests a cluster or two may eventually emerge
this evening across eastern CO and/or southwest KS, but this
potential remains highly uncertain. Mesoscale trends will be
monitored for a zone of more focused severe potential and possible
outlook upgrade.

...New York/Pennsylvania...
An amplified upper trough/low over Ontario and extending southward
into the Great Lakes/Midwest is forecast to gradually shift eastward
today. A related surface cold front will also advance
east-southeastward through the period across parts of the Northeast
and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly
moist low-level airmass ahead of the front will promote weak to
locally moderate instability this afternoon, especially across parts
of PA/NY. Current expectations are for thunderstorms to develop
along/near the front through the afternoon across western PA/NY.
While mid-level lapse rates are forecast to remain poor, which will
likely limit updraft strength, sufficient deep-layer shear should be
present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and
perhaps marginally severe hail as they spread eastward across
central PA and central/northern NY through early evening. This
activity should weaken with eastward extent as it encounters a less
unstable airmass.

$$

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ACUS01 KWNS 250101
SWODY1
SPC AC 250100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Aug 24 2025

Valid 250100Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
COLORADO TO THE TX/OK PANHANDLE AND WESTERN OKLAHOMA...

...SUMMARY...
A few severe thunderstorms are expected to continue evening across
the southern/central High Plains spanning from eastern Colorado into
western Oklahoma. Scattered strong to severe thunderstorms are also
possible for a few more hours across portions of Pennsylvania and
New York.

...Discussion...
Several thunderstorms are ongoing across southeast Colorado where a
few hail and wind reports have been received. These storms are
expected to congeal into larger clusters. However, the severe threat
should only last for a few more hours while moderate instability
remains. However, decreasing instability and increasing inhibition
should limit the overall threat by later this evening. See MCD 2012
for additional discussion of this threat area.

A few severe storms have developed across western Oklahoma this
evening where 1000 to 1500 J/kg MLCAPE and moderate shear is
present. These storms should persist for at least a few more hours
with a threat for large hail and severe wind gusts. Increasing
inhibition should reduce the threat by later this evening. See MCD
2011 for additional discussion of the near-term threat across this
area.

..Bentley.. 08/25/2025

$$

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ACUS01 KWNS 250601
SWODY1
SPC AC 250559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Mon Aug 25 2025

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN ARIZONA...

...SUMMARY...
Isolated severe gusts are possible over parts of south-central
Arizona this afternoon. Otherwise, potential for severe storms is
low across the remainder of the continental U.S.

...Synopsis...
A large upper-level trough will continue to amplify across the
eastern CONUS today. High pressure, currently analyzed across the
northern Plains early this morning will expand slowly southward
through the day which will push the polar front off the Atlantic
coast and perhaps into the Gulf. A persistent upper-level ridge will
exist across the Southwest and into the Great Basin/Rocky Mountains.
Beneath this ridge, a continued monsoon push will result in
widespread thunderstorm activity this afternoon/evening.

...Southern Arizona...
Monsoon thunderstorms are forecast to develop this afternoon/evening
across much of the Southwest amid weak to moderate instability
(1000-1500 J/kg MLCAPE) as temperatures cool aloft. A belt of
stronger mid-level southeasterly flow (20 to 25 knots) is forecast
to overspread the region and provide ample shear for some multicell
storm clusters. Initial storms which are expected to form across the
higher terrain in southeast Arizona may result in congealing outflow
with a damaging wind threat as storms move generally northwestward
through the evening.

..Bentley/Weinman.. 08/25/2025

$$

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ACUS01 KWNS 251240
SWODY1
SPC AC 251238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Mon Aug 25 2025

Valid 251300Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

..Synopsis...
A large upper-level trough will continue to amplify across the
eastern CONUS today. High pressure, currently analyzed across the
northern Plains early this morning will expand slowly southward
through the day which will push the polar front off the Atlantic
coast and perhaps into the Gulf. A persistent upper-level ridge will
exist across the Southwest and into the Great Basin/Rocky Mountains.
Beneath this ridge, a continued monsoon push will result in
widespread thunderstorm activity this afternoon/evening.

...Southern Arizona...
Thunderstorms are forecast to develop this afternoon/evening across
much of the Southwest amid weak to moderate instability (1000-1500
J/kg MLCAPE) as temperatures cool aloft. A belt of stronger
mid-level southeasterly flow (20-25 kt) is forecast to overspread
the region and provide ample shear for some multicell storm
clusters. Initial storms which are expected to form across the
higher terrain in southeast Arizona may result in congealing outflow
with a damaging wind threat as storms move generally
west-northwestward through the evening.

..Guyer/Kerr.. 08/25/2025

$$

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ACUS01 KWNS 251632
SWODY1
SPC AC 251631

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Mon Aug 25 2025

Valid 251630Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

...Synopsis...
A large upper trough will remain over the eastern CONUS today, as
several embedded shortwave troughs progress within its southern
periphery. Extensive upper ridging that currently extends from the
southern Plains into the northern Intermountain West is forecast to
remain largely in place. Some dampening may occur along the
northwestern periphery of this ridging as a slow-moving vorticity
maximum continues northeastward from the CO/OR/NV border vicinity
into more of eastern OR. Ample monsoonal moisture exists beneath
this ridging, contributing to scattered to numerous thunderstorms
from the southern/central Rockies westward across the Southwest and
much of the Great Basin. Limited vertical shear and weak buoyancy
will mitigate the severe potential across the majority of the
region. The only exceptions are across central Rockies and immediate
foothills, and portions of southern AZ.

...Southern AZ...
Ample monsoonal moisture is in place across the region, evidenced by
PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z
soundings, respectively. Filtered diurnal heating within this moist
airmass will support modest buoyancy and afternoon thunderstorm
development. A belt of stronger mid-level southeasterly flow (20-25
kt) is forecast to overspread the region this afternoon, providing
ample shear for some multicell storm clusters. Initial storms which
are expected to form across the higher terrain in southeast Arizona
may result in congealing outflow with a damaging wind threat as
storms move generally west-northwestward through the evening.

...Central Rockies...
Thunderstorm development is expected across the high terrain by the
early afternoon. Poor lapse rates and cooler temperatures will keep
buoyancy will be modest, likely limiting overall updraft strength
and tempering the severe potential. Even so, moderate northwesterly
flow aloft will support long hodographs and the potential for some
storm organization if updrafts can become sufficiently deep. An
instance or two of hail is possible with any stronger, more
long-lived storms.

..Mosier/Moore.. 08/25/2025

$$

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ACUS01 KWNS 251959
SWODY1
SPC AC 251957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Mon Aug 25 2025

Valid 252000Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
ARIZONA...

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.

...20z Update...
Scattered storms are currently developing over parts of southern AZ
and MX ahead of a weak MCV. Additional development is expected the
remainder of the afternoon into this evening. Limited buoyancy
(MLCAPE ~1000 J/kg) will support multicell updrafts atop fairly dry
low-levels. A few of the semi-organized storm clusters could support
stronger downdrafts with damaging gust potential. Minor changes were
made to the edges of MRGL risk area, see MCD #2014 for short-term
information. Elsewhere, scattered storms are expected over the
central and western CONUS today/tonight. Limited buoyancy and
vertical shear will keep the severe risk low. See the previous
discussion.

..Lyons.. 08/25/2025

.PREV DISCUSSION... /ISSUED 1131 AM CDT Mon Aug 25 2025/

...Synopsis...
A large upper trough will remain over the eastern CONUS today, as
several embedded shortwave troughs progress within its southern
periphery. Extensive upper ridging that currently extends from the
southern Plains into the northern Intermountain West is forecast to
remain largely in place. Some dampening may occur along the
northwestern periphery of this ridging as a slow-moving vorticity
maximum continues northeastward from the CO/OR/NV border vicinity
into more of eastern OR. Ample monsoonal moisture exists beneath
this ridging, contributing to scattered to numerous thunderstorms
from the southern/central Rockies westward across the Southwest and
much of the Great Basin. Limited vertical shear and weak buoyancy
will mitigate the severe potential across the majority of the
region. The only exceptions are across central Rockies and immediate
foothills, and portions of southern AZ.

...Southern AZ...
Ample monsoonal moisture is in place across the region, evidenced by
PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z
soundings, respectively. Filtered diurnal heating within this moist
airmass will support modest buoyancy and afternoon thunderstorm
development. A belt of stronger mid-level southeasterly flow (20-25
kt) is forecast to overspread the region this afternoon, providing
ample shear for some multicell storm clusters. Initial storms which
are expected to form across the higher terrain in southeast Arizona
may result in congealing outflow with a damaging wind threat as
storms move generally west-northwestward through the evening.

...Central Rockies...
Thunderstorm development is expected across the high terrain by the
early afternoon. Poor lapse rates and cooler temperatures will keep
buoyancy will be modest, likely limiting overall updraft strength
and tempering the severe potential. Even so, moderate northwesterly
flow aloft will support long hodographs and the potential for some
storm organization if updrafts can become sufficiently deep. An
instance or two of hail is possible with any stronger, more
long-lived storms.

$$

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ACUS01 KWNS 260047
SWODY1
SPC AC 260045

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Mon Aug 25 2025

Valid 260100Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL
PORTION OF SOUTH-CENTRAL ARIZONA....

...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona for a few more hours this evening. Otherwise, the potential
for severe storms is low across the remainder of the continental
U.S.

...Discussion...
A cluster of storms has produced some damaging winds across
south-central Arizona. As the boundary layer cools this evening,
expect these storms to weaken. However, the threat for isolated
damaging winds will persist for a few more hours amid 1000+ J/kg
DCAPE and steep low/mid level lapse rates.

Elsewhere, diurnal thunderstorms across the western CONUS will wane
this evening. Additional storms are expected to develop from the TX
Panhandle to western Oklahoma tonight, but weak instability should
limit any severe weather potential from this activity.

..Bentley.. 08/26/2025

$$

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ACUS01 KWNS 260559
SWODY1
SPC AC 260557

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Tue Aug 26 2025

Valid 261200Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe storms are not expected across the continental U.S. on
Tuesday.

...Synopsis...
An expansive upper-level trough will be present across the eastern
CONUS today. At the surface, a cool, dry airmass and high pressure
will dominate most of the eastern CONUS, limiting thunderstorm
potential. Widespread monsoonal thunderstorm activity will occur
across much of the western CONUS.

...Southern Arizona...
Weak instability is forecast across southern Arizona with sufficient
heating for thunderstorm development this afternoon. Mid-level flow
around 20 knots Tuesday morning will weaken slightly by the
afternoon. This belt of enhanced flow may provide enough shear for a
stronger multicell thunderstorm with an isolated damaging wind
threat. However, overall, expect storm organization to be limited
with mostly sub-severe convection due to weaker instability and
shear than Monday.

Given the number of storms across the western CONUS today, isolated
damaging wind gusts may be possible. However, a more organized
region/threat is not apparent.

..Bentley/Weinman.. 08/26/2025

$$

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ACUS01 KWNS 261249
SWODY1
SPC AC 261248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Tue Aug 26 2025

Valid 261300Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe storms are not expected across the continental U.S.
today.

...Synopsis...
An expansive upper-level trough will persist across the eastern
CONUS today, where a cool, dry airmass and high pressure
will be prevalent and limit thunderstorm potential aside from
Florida. Monsoon-related scattered thunderstorms will be common
across much of the non-coastal West.

...Southern Arizona/Lower Colorado River Valley...
A northward-moving mid-level impulse/MCV will spread from the Lower
Colorado River Valley/northern Arizona this morning into Utah,
allowing for subsequent clearing/heating across southern Arizona
toward the Lower Colorado River Valley. Thunderstorms will again
develop and increase this afternoon especially in vicinity of higher
terrain. A few instances of strong thunderstorm winds/wet
microbursts could occur regionally this afternoon into evening, but
the overall potential is expected to remain quite isolated and
marginal overall.

..Guyer/Kerr.. 08/26/2025

$$

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ACUS01 KWNS 261622
SWODY1
SPC AC 261620

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1120 AM CDT Tue Aug 26 2025

Valid 261630Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...Synopsis and Discussion...
Large-scale upper troughing will remain over the eastern CONUS
today, with surface high pressure dominating much of the
central/eastern CONUS. Isolated thunderstorms may occur this
afternoon and evening along/south of a surface cold front across
parts of the FL Peninsula and central/south TX. However, weak flow
aloft and related deep-layer shear should preclude an organized
severe threat across these regions with this activity.

Scattered to numerous thunderstorms are expected to develop today
across much of the interior western CONUS, as upper ridging weakens
over the Southwest and multiple weak mid-level perturbations move north-northeastward across the Sierras and Great Basin. Ongoing
thunderstorms this morning across the Central Valley in CA will be
in a relatively more favorable thermodynamic environment, with
modestly steepened mid-level lapse rates compared to locations
farther east over the Great Basin potentially supporting small hail
with the stronger cores. Still, shear is expected to remain modest
at best with westward extent, which should limit updraft
organization and overall severe potential.

Isolated strong/gusty winds may also occur with any convection that
can develop over parts of interior southern CA into the lower CO
River Valley, particularly where steepened low-level lapse rates can
develop with daytime heating/mixing of the boundary layer away from
ongoing cloud cover. The potential for a more concentrated corridor
of severe winds still appears low across this area, as it will be in
a generally subsident regime behind a weak mid-level shortwave
trough advancing northward from southern NV across the Great Basin
this afternoon.

Finally, an occasional/very isolated strong to severe gust cannot be
ruled out across the Four Corners region this afternoon, as
convection develops along the Mogollon Rim in northern AZ and
subsequently spreads north-northeastward in tandem with a weak
mid-level shortwave trough. Even so, deep-layer shear appears too
marginal to include low severe wind probabilities with this update.

..Gleason/Moore.. 08/26/2025

$$

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ACUS01 KWNS 261958
SWODY1
SPC AC 261956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Aug 26 2025

Valid 262000Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...20Z Update...
Isolated strong storms remain possible in the Four Corners vicinity
this afternoon. Observed 18Z soundings from Tucson and Flagstaff
indicate relatively poor mid-level lapse rates and marginal
effective shear. Areas of stronger surface heating could promote
stronger outflow winds, but organized severe storms are still
unlikely. Only minor modifications were made to the general thunder
area based on current observations. Additional forecast details are
in the previous discussion below.

..Wendt.. 08/26/2025

.PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 26 2025/

...Synopsis and Discussion...
Large-scale upper troughing will remain over the eastern CONUS
today, with surface high pressure dominating much of the
central/eastern CONUS. Isolated thunderstorms may occur this
afternoon and evening along/south of a surface cold front across
parts of the FL Peninsula and central/south TX. However, weak flow
aloft and related deep-layer shear should preclude an organized
severe threat across these regions with this activity.

Scattered to numerous thunderstorms are expected to develop today
across much of the interior western CONUS, as upper ridging weakens
over the Southwest and multiple weak mid-level perturbations move north-northeastward across the Sierras and Great Basin. Ongoing
thunderstorms this morning across the Central Valley in CA will be
in a relatively more favorable thermodynamic environment, with
modestly steepened mid-level lapse rates compared to locations
farther east over the Great Basin potentially supporting small hail
with the stronger cores. Still, shear is expected to remain modest
at best with westward extent, which should limit updraft
organization and overall severe potential.

Isolated strong/gusty winds may also occur with any convection that
can develop over parts of interior southern CA into the lower CO
River Valley, particularly where steepened low-level lapse rates can
develop with daytime heating/mixing of the boundary layer away from
ongoing cloud cover. The potential for a more concentrated corridor
of severe winds still appears low across this area, as it will be in
a generally subsident regime behind a weak mid-level shortwave
trough advancing northward from southern NV across the Great Basin
this afternoon.

Finally, an occasional/very isolated strong to severe gust cannot be
ruled out across the Four Corners region this afternoon, as
convection develops along the Mogollon Rim in northern AZ and
subsequently spreads north-northeastward in tandem with a weak
mid-level shortwave trough. Even so, deep-layer shear appears too
marginal to include low severe wind probabilities with this update.

$$

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ACUS01 KWNS 270050
SWODY1
SPC AC 270049

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 PM CDT Tue Aug 26 2025

Valid 270100Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.

...Discussion...
Mostly unorganized thunderstorm activity has been prevalent across
the western CONUS this evening. A few stronger storms and isolated
stronger cores have been present. However, the severe potential has
been limited and will remain so through the overnight period.

..Bentley.. 08/27/2025

$$

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ACUS01 KWNS 270557
SWODY1
SPC AC 270556

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Wed Aug 27 2025

Valid 271200Z - 281200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The potential for severe storms appears to be low across the
continental U.S. today, though a few stronger storms are possible
across parts of the Upper Midwest and Colorado Front Range where
locally gusty winds and small hail are possible.

...Synopsis...
A broad upper-level trough will be present across the eastern CONUS
today with weak ridging across the western CONUS. Surface high
pressure will weaken slightly and shift east across the Appalachians
into the Mid-Atlantic/Carolinas. A cold front along the Gulf Coast
will extend into the Central Plains.

...Upper Midwest...
A region of moderate instability and shear is forecast to develop
across southern Minnesota this afternoon. A lead shortwave trough
(currently across north Dakota) is expected to move through southern
Minnesota around mid-day with weak height rises and subsidence in
its wake. However, by the evening, an additional shortwave trough
(traversing the western edge of the broader trough) may result in
isolated storm development by late afternoon/early evening. Some
forecast sounding, particularly the NAM, would support a few strong
to isolated severe storms with a threat for large hail. However,
consensus guidance is not as unstable and therefore, any severe
threat may remain mostly isolated. Therefore, no severe weather
probabilities will be included at this time.

...Central High Plains into western Kansas...
Thunderstorms across the central High Plains may congeal into a
cluster as they move into western Kansas this evening. A belt of
stronger mid-level flow (35 to 45 knots) on the southwest periphery
of the large-scale trough will provide favorable deep-layer shear
across the region. However, despite the favorable shear, weak
mid-level lapse rates will limit overall instability. A few stronger
storms capable of damaging winds will be possible, but this threat
is expected to be too low/limited to warrant severe weather
probabilities.

..Bentley/Weinman.. 08/27/2025

$$

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ACUS01 KWNS 271254
SWODY1
SPC AC 271253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Wed Aug 27 2025

Valid 271300Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
COLORADO...

...SUMMARY...
Some strong to locally severe storms may occur across eastern
Colorado and the central High Plains late this afternoon and early
evening.

...Eastern Colorado/Central High Plains...
Prevalent cloud cover and some lingering mostly light precipitation
should eventually abate later this afternoon, with thunderstorms
expected to develop/increase initially over the mountains by around mid-afternoon. These storms will spread east-southeastward toward
the instability axis across the adjacent High Plains through early
evening. Moderately strong mid-level flow could support some
semi-organized storms, and a couple of clusters could evolve by
evening. Localized instances of marginally severe hail and/or wind
could occur, although locally heavy rainfall may be more of a
prevalent concern.

...Upper Midwest...
A region of moderate instability is forecast to develop from eastern
South Dakota into southern Minnesota this afternoon. But this will
be in the wake of a southeastward-moving shortwave trough, with weak
height rises and subsidence in its wake. Nonetheless, isolated storm development may occur by late afternoon/early evening, and a few
strong storms are conceivable.

..Guyer/Kerr.. 08/27/2025

$$

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ACUS01 KWNS 271629
SWODY1
SPC AC 271628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Aug 27 2025

Valid 271630Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS AND UPPER MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur across parts of
the central High Plains and Upper Midwest this afternoon and early
evening.

...Central High Plains...
Upper ridging should remain suppressed over TX today, with modest
mid-level westerly flow persisting across the central Plains. Late
morning visible satellite imagery shows some clearing across eastern
CO, which should aid in diurnal destabilization this afternoon.
Gradual low-level moisture return is forecast to continue today
across the central High Plains, generally along and east of a weak
lee trough/low where low to mid 60s surface dewpoints are present.
With scattered to numerous thunderstorms over much of the Southwest
and southern/central Rockies yesterday, there is not a notable EML
present over the central High Plains today (reference 12Z observed
DDC sounding). This should temper the degree of instability that can
develop through the afternoon to some extent. Even so, around
500-1500 J/kg of MLCAPE appears plausible with additional diurnal
heating of the modestly moistened low-level airmass.

Weak low-level southerly flow will veer to westerly and gradually
strengthen with height through mid/upper levels, supporting around
25-40 kt of deep-layer shear. Thunderstorms are expected to develop
initially along/near the Front Range this afternoon, before
spreading slowly east-southeastward across eastern CO and parts of
western KS through the evening. Isolated severe hail may occur with
the strongest cores/marginal supercell structures, until gradual
outflow/cold pool amalgamation encourages one or more clusters with
a greater threat for occasional strong to severe gusts. Based on
latest observational and short-term guidance trends, the Marginal
Risk has been expanded to include more of eastern CO and western KS.
Mainly elevated thunderstorms will likely continue overnight into central/eastern KS in a modest low-level warm advection regime.
However, confidence in a continued hail/wind threat with this
activity remains low at this time.

...Upper Midwest...
On the western side of a large-scale upper trough over eastern
Canada and the Atlantic Coast states, modestly enhanced
northwesterly mid-level flow is forecast to persist through much of
the period. A weak embedded shortwave trough moving across southern
MN and vicinity late this morning suggests modest large-scale
subsidence in its wake. This casts some uncertainty on the possible
development of isolated to scattered thunderstorms later today
along/south of a weak surface trough across eastern SD into
central/southern MN. Even so, most guidance suggests at least
isolated thunderstorms will form across this region by late
afternoon/early evening. Cool mid-level temperatures and generally long/straight hodographs aloft suggest some threat for severe hail
with any of the stronger cores that can be sustained. Have therefore
added a focused Marginal Risk across parts of eastern SD into
southern MN for this potential.

..Gleason/Moore.. 08/27/2025

$$

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ACUS01 KWNS 271955
SWODY1
SPC AC 271954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Wed Aug 27 2025

Valid 272000Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
CENTRAL HIGH PLAINS AND THE UPPER MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur across parts of
the central High Plains and Upper Midwest this afternoon and early
evening.

...20Z Update...
The forecast remains on track with only minor adjustments to the
general thunderstorm forecast. See the previous discussion for
additional information.

..Wendt.. 08/27/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 27 2025/

...Central High Plains...
Upper ridging should remain suppressed over TX today, with modest
mid-level westerly flow persisting across the central Plains. Late
morning visible satellite imagery shows some clearing across eastern
CO, which should aid in diurnal destabilization this afternoon.
Gradual low-level moisture return is forecast to continue today
across the central High Plains, generally along and east of a weak
lee trough/low where low to mid 60s surface dewpoints are present.
With scattered to numerous thunderstorms over much of the Southwest
and southern/central Rockies yesterday, there is not a notable EML
present over the central High Plains today (reference 12Z observed
DDC sounding). This should temper the degree of instability that can
develop through the afternoon to some extent. Even so, around
500-1500 J/kg of MLCAPE appears plausible with additional diurnal
heating of the modestly moistened low-level airmass.

Weak low-level southerly flow will veer to westerly and gradually
strengthen with height through mid/upper levels, supporting around
25-40 kt of deep-layer shear. Thunderstorms are expected to develop
initially along/near the Front Range this afternoon, before
spreading slowly east-southeastward across eastern CO and parts of
western KS through the evening. Isolated severe hail may occur with
the strongest cores/marginal supercell structures, until gradual
outflow/cold pool amalgamation encourages one or more clusters with
a greater threat for occasional strong to severe gusts. Based on
latest observational and short-term guidance trends, the Marginal
Risk has been expanded to include more of eastern CO and western KS.
Mainly elevated thunderstorms will likely continue overnight into central/eastern KS in a modest low-level warm advection regime.
However, confidence in a continued hail/wind threat with this
activity remains low at this time.

...Upper Midwest...
On the western side of a large-scale upper trough over eastern
Canada and the Atlantic Coast states, modestly enhanced
northwesterly mid-level flow is forecast to persist through much of
the period. A weak embedded shortwave trough moving across southern
MN and vicinity late this morning suggests modest large-scale
subsidence in its wake. This casts some uncertainty on the possible
development of isolated to scattered thunderstorms later today
along/south of a weak surface trough across eastern SD into
central/southern MN. Even so, most guidance suggests at least
isolated thunderstorms will form across this region by late
afternoon/early evening. Cool mid-level temperatures and generally long/straight hodographs aloft suggest some threat for severe hail
with any of the stronger cores that can be sustained. Have therefore
added a focused Marginal Risk across parts of eastern SD into
southern MN for this potential.

$$

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ACUS01 KWNS 280055
SWODY1
SPC AC 280053

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 PM CDT Wed Aug 27 2025

Valid 280100Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms remain possible across parts
of the central High Plains early this evening.

...01z Update...

Scattered convection persists across much of the western United
States early this evening, primarily driven by strong boundary-layer
heating. Much of this activity will gradually weaken as the evening
progresses. A corridor of modest instability persists across the
central High Plains and a few small clusters are noted across
eastern Colorado into southwest Kansas. Weak low-level warm
advection will maintain this activity into the mid-evening hours,
with some upscale growth possible downstream later tonight as LLJ
strengthens. Even so, most of this convection should remain
sub-severe.

..Darrow.. 08/28/2025

$$

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ACUS01 KWNS 280538
SWODY1
SPC AC 280537

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Thu Aug 28 2025

Valid 281200Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE SOUTHERN PLAINS INTO THE ARKLATEX...AND ACROSS EASTERN
COLORADO...

...SUMMARY...
Strong thunderstorms, with an isolated severe wind threat, are
possible across parts of the southern Plains into the Arklatex this
afternoon and evening. Isolated severe thunderstorms are also
possible across eastern Colorado.

...Southern Plains/Arklatex...

Weak short-wave trough is evident in water-vapor imagery over the
central High Plains. This feature is digging southeast in line with
latest model guidance. A substantial amount of convection is
currently noted just ahead of this feature across western into south
central KS. This activity should gradually grow upscale through
sunrise as LLJ veers into northeast OK by late morning. Associated
rain-cooled boundary layer air mass will reinforce a surface
boundary currently draped across the southern Plains. Latest model
guidance suggests strong surface heating will contribute to
substantial destabilization across much of southern OK into
northeast TX, immediately south of the front. While mid-level
temperatures are seasonally warm (-4C at 500mb), and lapse rates are
not that steep, some risk for an isolated wind gusts or marginally
severe hail can be expected with the more robust convection.
Deepening northwesterly flow will encourage an MCS to spread from
northeast OK into southern AR, and the southwestern flank of this
activity will be more influenced by higher buoyancy along the Red
River corridor.

...Eastern CO...

Large-scale pattern is not expected to change appreciably during the
day1 period as upper ridging will hold across the southern/central
Rockies. While mid-level flow is not that strong across CO,
low-level upslope flow is expected to contribute to scattered
thunderstorm development as boundary layer heats later this
afternoon. This activity will spread southeast with an attendant
risk for at least gusty winds and isolated hail.

..Darrow/Weinman.. 08/28/2025

$$

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ACUS01 KWNS 281251
SWODY1
SPC AC 281249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Thu Aug 28 2025

Valid 281300Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
OKLAHOMA AND ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...Southern Oklahoma/North Texas to ArkLaTex...
Showers/thunderstorms are prevalent this morning across
northern/eastern Oklahoma into the Ozarks to the north-northeast of
a warm front. Within a belt of moderately strong northwesterly flow
aloft, a shortwave trough will continue to dig southeastward from
the south-central Plains toward the Ozarks by this evening. Related
dynamical response and the early day convection will shunt the front
southward later today, with ample heating/moderate destabilization
on the southwest flank of this boundary.

While mid-level temperatures are seasonally warm (-4C at 500 mb),
and lapse rates are not that steep, severe hail and damaging wind
gusts can be expected with the more robust convection as general intensification occurs by mid/late afternoon. A few initial
supercells may occur, and some tornado risk could also exist with
convection immediately along the boundary and east of the weak
surface front. Clustering/upscale-quasi-linear growth should occur
by early evening as storms progress southeastward and continue to
pose a damaging wind risk for a time this evening.

...Eastern Colorado and adjacent High Plains...
The large-scale pattern is not expected to change appreciably as
upper ridging will hold across the southern/central Rockies. While
mid-level flow is not that strong across Colorado, low-level upslope
flow is expected to contribute to scattered thunderstorm development
as boundary layer heats later this afternoon. This activity will
spread southeastward with an attendant risk for isolated severe hail
and gusty winds.

..Guyer/Kerr.. 08/28/2025

$$

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ACUS01 KWNS 281618
SWODY1
SPC AC 281616

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1116 AM CDT Thu Aug 28 2025

Valid 281630Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
OKLAHOMA AND ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...Southern Oklahoma/North Texas to ArkLaTex...
Widespread showers and thunderstorms are ongoing from
central/eastern OK southeastward across northern/central AR and into northern/central MS. This area of precipitation is occurring along
and north of a warm-front-like boundary that extends from the TX
Panhandle southeastward through south-central OK into northeast TX.
General expectation is for the ongoing storms to persist throughout
the day, supported mainly by modest mid-level southwesterlies and
associated warm-air advection across the boundary. Additionally,
this boundary will likely sharpen throughout the day as the precipitation/cloudiness continue north of the boundary, and
warm/moist conditions persist south of the boundary.

The ongoing elevated storms across southeast OK will likely continue southeastward, likely resulting in a small corridor where diurnal
heating is possible in the vicinity of the warm front, but ahead of
the slowly progressing outflow moving across central/south-central
OK. This heating of the moist airmass in place could result in a
corridor of moderate to strong buoyancy, despite relatively warm
temperatures aloft and poor lapse rates. This buoyancy coupled with
moderate deep-layer vertical shear provided by the moderate
northwesterly flow aloft could result in a few strong and organized
updrafts. Given current trends, a reintensification of cells along
the outflow appears to be the most likely convective evolution, with
the resulting linear mode favoring damaging gusts as the primary
risk. That being said, given continued low-level moisture
convergence near the warm front, more discrete development ahead of
the outflow is also a possibility. Any more discrete storms could
become supercellular, with a low-probability risk for a tornado
and/or hail, particularly near the surface boundary.

Additional development is possible this afternoon along the western
edge of the outflow across southwest OK and the TX Big Country/Low
Rolling Plains. A few stronger storms capable of damaging gusts are
possible in these areas.

...Central High Plains...
Low-level upslope flow is expected to contribute to scattered
thunderstorm development the as boundary layer heats across the
central High Plains later this afternoon. Moderate mid-level flow
atop low-level easterlies will result in around 35-40 kt of
effective bulk shear, which is strong enough to support organized
storm structures. This activity will spread southeastward towards
the lower terrain over time, with an attendant risk for isolated
severe hail and gusty winds.

..Mosier/Moore.. 08/28/2025

$$

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ACUS01 KWNS 281944
SWODY1
SPC AC 281943

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0243 PM CDT Thu Aug 28 2025

Valid 282000Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST OKLAHOMA
INTO THE ARKLATEX...

...SUMMARY...
Strong thunderstorms, with an isolated hail and severe wind threat,
are possible across parts of southern Oklahoma and northern Texas to
the Arklatex this afternoon and evening. Isolated severe
thunderstorms will also be possible across eastern Colorado and the
adjacent High Plains.

...20Z Update...
Based on current observations and convective trends, changes were
made to the general thunderstorm forecast. The Slight risk in the
ArkLaTex vicinity was also trimmed behind ongoing convection. The
remainder of the forecast remains on track. Additional information
is found in the previous discussion below.

..Wendt.. 08/28/2025

.PREV DISCUSSION... /ISSUED 1116 AM CDT Thu Aug 28 2025/

...Southern Oklahoma/North Texas to ArkLaTex...
Widespread showers and thunderstorms are ongoing from
central/eastern OK southeastward across northern/central AR and into northern/central MS. This area of precipitation is occurring along
and north of a warm-front-like boundary that extends from the TX
Panhandle southeastward through south-central OK into northeast TX.
General expectation is for the ongoing storms to persist throughout
the day, supported mainly by modest mid-level southwesterlies and
associated warm-air advection across the boundary. Additionally,
this boundary will likely sharpen throughout the day as the precipitation/cloudiness continue north of the boundary, and
warm/moist conditions persist south of the boundary.

The ongoing elevated storms across southeast OK will likely continue southeastward, likely resulting in a small corridor where diurnal
heating is possible in the vicinity of the warm front, but ahead of
the slowly progressing outflow moving across central/south-central
OK. This heating of the moist airmass in place could result in a
corridor of moderate to strong buoyancy, despite relatively warm
temperatures aloft and poor lapse rates. This buoyancy coupled with
moderate deep-layer vertical shear provided by the moderate
northwesterly flow aloft could result in a few strong and organized
updrafts. Given current trends, a reintensification of cells along
the outflow appears to be the most likely convective evolution, with
the resulting linear mode favoring damaging gusts as the primary
risk. That being said, given continued low-level moisture
convergence near the warm front, more discrete development ahead of
the outflow is also a possibility. Any more discrete storms could
become supercellular, with a low-probability risk for a tornado
and/or hail, particularly near the surface boundary.

Additional development is possible this afternoon along the western
edge of the outflow across southwest OK and the TX Big Country/Low
Rolling Plains. A few stronger storms capable of damaging gusts are
possible in these areas.

...Central High Plains...
Low-level upslope flow is expected to contribute to scattered
thunderstorm development the as boundary layer heats across the
central High Plains later this afternoon. Moderate mid-level flow
atop low-level easterlies will result in around 35-40 kt of
effective bulk shear, which is strong enough to support organized
storm structures. This activity will spread southeastward towards
the lower terrain over time, with an attendant risk for isolated
severe hail and gusty winds.

$$

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ACUS01 KWNS 290047
SWODY1
SPC AC 290046

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 PM CDT Thu Aug 28 2025

Valid 290100Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS AND FROM NORTH-CENTRAL TEXAS INTO NORTHERN
LOUISIANA...

...SUMMARY...
Thunderstorms capable of a marginal severe threat will be possible
early this evening across parts of eastern Colorado and from
north-central Texas into northern Louisiana.

...Eastern Colorado...
At mid-levels, the latest water vapor imagery shows a ridge over the
central Rockies with a large plume of moisture extending from the
Desert Southwest into the central High Plains. At the surface, high
pressure, associated with a large post-frontal airmass, is located
over much of the central and eastern U.S. Along the western edge of
the airmass, an upslope flow regime is present over the central High
Plains. Relatively isolated thunderstorms are ongoing in eastern
Colorado near an axis of instability, where the RAP has MLCAPE in
the 1000 to 1500 J/kg range. In addition, regional WSR-88D VWPs near
the instability axis have 0-6 km shear around 40 knots. This suggest
the environment could support a marginal severe threat early this
evening. Hail and isolated severe gusts would be the primary
threats.

...North-central/Northeast Texas/Northern Louisiana...
Northwesterly mid-level flow is evident on water vapor imagery from
the Great Plains into the Southeast. A mid-level shortwave trough
appears to be moving through the Lower Mississippi Valley. Scattered thunderstorms are ongoing just ahead of the shortwave over northern
Louisiana, extending westward along a front into northeast and
north-central Texas. To the south of the front, surface dewpoints in
the 70s F are contributing to moderate instability, with the RAP
analyzing MLCAPE in the 1500 to 3000 J/kg range. Near the front, the
00Z soundings at Fort Worth and Shreveport have 0-6 km shear around
30 knots with steep low-level lapse rates. This could be enough for
isolated severe gusts early this evening. Hail will also be
possible.

..Broyles.. 08/29/2025

$$

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ACUS01 KWNS 290458
SWODY1
SPC AC 290457

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1157 PM CDT Thu Aug 28 2025

Valid 291200Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...AND IN PARTS OF THE SABINE
RIVER VALLEY...

...SUMMARY...
Thunderstorms with potential for hail and isolated severe gusts will
be possible today across parts of the southern and central High
Plains. A few marginally severe gusts could also occur over parts of
the Sabine River Valley.

...Southern and Central High Plains...
At mid-levels, flow will be northwesterly over much of the central
U.S. today, as a ridge remains in place over the central High
Plains. At the surface, a low is forecast to move eastward through
southwestern South Dakota as a lee trough deepens across western
Nebraska and eastern Colorado. As surface temperatures warm and
low-level convergence increases, scattered thunderstorms are
expected to develop near the surface trough. Along and to the east
of the trough, surface dewpoints in the lower to mid 60s F will
contribute to an axis of moderate instability by afternoon. In
addition, RAP forecast soundings along this corridor show moderate
deep-layer shear, owing mostly to speed shear in the mid-levels.
This instability/shear environment could be enough for a marginal
severe threat late this afternoon and early this evening, with the
primary threats being for hail and isolated severe gusts.

...Sabine River Valley...
A mid-level trough will move across the eastern U.S. today, as
cyclonically curved northwesterly flow remains over much of the
Southeast. At the surface, a slow-moving front will be positioned
from east Texas eastward into the central Gulf Coast states.
Thunderstorms are expected to be ongoing near the front in the
morning. This convection should move southeastward across the lower
Mississippi Valley during the day. To the southwest of this
convection, the airmass will remain undisturbed from southeast Texas
into southwest Louisiana. This will allow for stronger surface
heating, which should result in a pocket of moderate instability by
afternoon. Isolated thunderstorms that develop within this pocket of instability could produce marginally severe wind gusts, mainly when
low-level lapse rates become steep in the mid to late afternoon.

..Broyles/Thornton.. 08/29/2025

$$

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ACUS01 KWNS 291254
SWODY1
SPC AC 291252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Fri Aug 29 2025

Valid 291300Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL/SOUTHERN HIGH PLAINS AND SABINE RIVER VALLEY...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains. A few marginally
severe storms could also occur today over parts of the Sabine River
Valley.

...Central/southern High Plains...
Multiple ridge-riding mid/upper-level disturbances will transition
generally east/eventually southeastward from the central Rockies and
northern High Plains today. Weak lee-side low development will occur
across southeast Colorado and also perhaps farther north across the
central High Plains, with modestly sharpening low-level convergence
in vicinity of the lee trough. This will lead to a gradual
enhancement of low-level upslope flow particularly across east-central/southeast Colorado and northeast New Mexico.

Storms should develop/increase by mid-afternoon and gradually move
eastward off the Colorado mountains/Raton Mesa vicinity, with other
development occurring near the surface boundary extending
north-northeastward into west-central Nebraska/southern South
Dakota. Surface dewpoints in the lower to mid 60s F will contribute
to an axis of moderate instability by peak heating. With moderately
strong northwesterly mid-level flow persisting regionally, 35-40 kt
or greater effective shear will exist from the Raton Mesa vicinity
across the central High Plains into west-central Nebraska. A few
supercells capable of large hail may occur, with the additional
possibility of wind damage, especially with a probable clustering of
storms across eastern Colorado/northeast New Mexico toward western
Kansas and the Oklahoma/Texas Panhandles.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms are
ongoing this morning across northeast Texas to central/southeast
Louisiana to the north of a front that will settle southward today
across the region. A related cloud canopy will extend southward into
the warm sector, but moderate destabilization should occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop near the front this afternoon, with isolated instances of
damaging winds a possibility as low-level lapse rates steepen.

..Guyer/Bentley.. 08/29/2025

$$

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ACUS01 KWNS 291628
SWODY1
SPC AC 291626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Fri Aug 29 2025

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
WESTERN/CENTRAL NEBRASKA...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains. A few marginally
severe storms could also occur today over parts of the Sabine River
Valley.

...Central/Southern High Plains...
Recent surface analysis show a reservoir of low-level moisture
across the central/southern High Plains, varying from the mid 60s
across eastern NM into the lower 60s across northeast CO and the NE
Panhandle. General expectation is for modest upslope flow to
contribute to another day of afternoon/evening thunderstorms across
much of central/eastern CO and eastern NM. Thunderstorms also look
probable farther north in the vicinity of a weak surface low, which
is expected to develop along a sharpening lee trough over the NE
Panhandle. Current surface low over western SD will likely fill
throughout the day, although there could still be enough low-level
convergence near the remnant troughing to support a few
thunderstorms as well. In general, there looks to be more overall
storm coverage than the last few days.

Some modest enhancement of the mid-level flow is possible as the
low-amplitude shortwave trough currently over southern UT continues northeastward through the periphery of the ridge into the central
Rockies. The strongest flow will extend from northern CO/southeast
WY into central NE, where elongated hodographs result in a wind
profile that supports supercells capable of large hail. Lapse rates
are generally poor, but ample low-level moisture should still result
in enough buoyancy for mature updrafts. Highest storm coverage
across this region is anticipated over western NE, where 15% hail
probabilities were introduced.

A secondary area of greater storm coverage is expected farther south
from southeast CO through northeast NM as storms move eastward off
the Colorado mountains/Raton Mesa vicinity. Mid-level westerly flow
will be a bit weaker here than farther north but should still be
sufficient for around 35-40 kt of effective bulk shear. Lapse rates
are poor and overall storm strength will likely be limited by
tempered buoyancy. Even so, multicells and a supercell or two are
still possible initially, with eventual clustering as storms move
across eastern Colorado/northeast New Mexico toward western Kansas
and the Oklahoma/Texas Panhandles. Isolated hail is possible with
the initially more cellular storms, with a trend towards damaging
gusts as storms become more linear.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms is
ongoing this morning from east Texas into central/southeast
Louisiana, to the north of a front that will continue to settle
southward today. A related cloud canopy extends across the warm
sector, but moderate destabilization should still occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop this afternoon, with isolated instances of damaging winds a
possibility as low-level lapse rates steepen.

..Mosier/Lyons.. 08/29/2025

$$

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ACUS01 KWNS 291959
SWODY1
SPC AC 291958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri Aug 29 2025

Valid 292000Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF
WESTERN/CENTRAL NEBRASKA...SOUTHEAST COLORADO AND ADJACENT AREAS...

...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains.

...20Z Update...
Given observational and CAM guidance trends, an area of greater
supercell potential appears evident in parts of southeast Colorado
and nearby vicinity. Discrete storms would be most likely within the
surface trough. A cluster or two of storms could also potentially
move off the higher terrain later this afternoon. Large hail and
isolated severe winds would be the primary threats, though a brief
tornado could occur in the surface trough.

Observational trends also suggest limited potential for severe
storms in the Sabine Valley region. Severe probabilities have been
removed.

..Wendt.. 08/29/2025

.PREV DISCUSSION... /ISSUED 1126 AM CDT Fri Aug 29 2025/

...Central/Southern High Plains...
Recent surface analysis show a reservoir of low-level moisture
across the central/southern High Plains, varying from the mid 60s
across eastern NM into the lower 60s across northeast CO and the NE
Panhandle. General expectation is for modest upslope flow to
contribute to another day of afternoon/evening thunderstorms across
much of central/eastern CO and eastern NM. Thunderstorms also look
probable farther north in the vicinity of a weak surface low, which
is expected to develop along a sharpening lee trough over the NE
Panhandle. Current surface low over western SD will likely fill
throughout the day, although there could still be enough low-level
convergence near the remnant troughing to support a few
thunderstorms as well. In general, there looks to be more overall
storm coverage than the last few days.

Some modest enhancement of the mid-level flow is possible as the
low-amplitude shortwave trough currently over southern UT continues northeastward through the periphery of the ridge into the central
Rockies. The strongest flow will extend from northern CO/southeast
WY into central NE, where elongated hodographs result in a wind
profile that supports supercells capable of large hail. Lapse rates
are generally poor, but ample low-level moisture should still result
in enough buoyancy for mature updrafts. Highest storm coverage
across this region is anticipated over western NE, where 15% hail
probabilities were introduced.

A secondary area of greater storm coverage is expected farther south
from southeast CO through northeast NM as storms move eastward off
the Colorado mountains/Raton Mesa vicinity. Mid-level westerly flow
will be a bit weaker here than farther north but should still be
sufficient for around 35-40 kt of effective bulk shear. Lapse rates
are poor and overall storm strength will likely be limited by
tempered buoyancy. Even so, multicells and a supercell or two are
still possible initially, with eventual clustering as storms move
across eastern Colorado/northeast New Mexico toward western Kansas
and the Oklahoma/Texas Panhandles. Isolated hail is possible with
the initially more cellular storms, with a trend towards damaging
gusts as storms become more linear.

...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms is
ongoing this morning from east Texas into central/southeast
Louisiana, to the north of a front that will continue to settle
southward today. A related cloud canopy extends across the warm
sector, but moderate destabilization should still occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop this afternoon, with isolated instances of damaging winds a
possibility as low-level lapse rates steepen.

$$

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ACUS01 KWNS 300039
SWODY1
SPC AC 300038

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 PM CDT Fri Aug 29 2025

Valid 300100Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Thunderstorms with potential for hail and isolated severe gusts will
be possible from early to mid evening across parts of the southern
and central High Plains.

...Southern and Central High Plains...
On water vapor imagery, northwesterly mid-level flow is evident over
much of the central U.S. with a ridge over the central High Plains.
At the surface, a moist airmass is located across the southern and
central Plains, where dewpoints are mostly in the 60s F. An axis of
moderate instability is analyzed along the western edge of the moist
airmass from far eastern New Mexico north-northeastward into
west-central Nebraska. Scattered strong thunderstorms are ongoing
near the instability axis, with a few that are severe. The wind
profile on the WSR-88D VWP at Dodge City appears to be
representative along the instability axis, with 0-6 km shear near 45
knots and strong mid-level speed shear. This will continue to
support a marginal severe threat from early to mid evening, mainly
with the storms that are close to the instability axis. Hail and
isolated severe gusts will be the primary threats. The severe threat
will gradually diminish as instability decreases over the next few
hours.

..Broyles.. 08/30/2025

$$

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ACUS01 KWNS 300552
SWODY1
SPC AC 300551

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Sat Aug 30 2025

Valid 301200Z - 311200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few strong thunderstorms will be possible across parts of the
southern and central Plains today, but any severe potential should
remain low.

...DISCUSSION...
Flow at mid-levels will remain northwesterly over the top of a moist
airmass today in the southern and central Plains. A weak upslope
flow regime will be in place to the east of a surface trough over
eastern New Mexico and the Texas Panhandle. As surface temperatures
warm during the day across this airmass, scattered thunderstorms
will develop. Isolated storms may form near the surface trough and
instability axis, with increased convective coverage further to the
east in the less unstable air. A few strong storms will be possible
in areas where convection is co-located with maximized instability.
However, lapse rates will be weak suggesting that the severe
potential will remain low in the southern and central Plains today.
Elsewhere across the continental U.S., no severe threat is expected
today and tonight.

..Broyles/Thornton.. 08/30/2025

$$

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ACUS01 KWNS 301250
SWODY1
SPC AC 301248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Aug 30 2025

Valid 301300Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS...

...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.

...Southern High Plains...
A belt of moderate-strength west-northwesterly flow aloft will
persist atop a moist airmass regionally. Post-MCS air mass
influences and lingering cloud cover/outflows may be factors into
the afternoon, but RAP/HRRR-related guidance has trended a bit more
unstable and potentially more conducive to some isolated severe
storms later today. While confidence in forecast details are not
particularly high, this potential appears to be mainly focused in a
corridor across northeast New Mexico into the Texas Panhandle/Texas
South Plains, and possibly western Oklahoma later this afternoon
into evening. This is where locally moderate destabilization may
occur coincident with effective shear magnitudes that may reach
30-40 kt, with storm development focused near the surface trough
and/or influenced by differential heating. A few instances of severe
hail and/or wind will be possible.

..Guyer/Bentley.. 08/30/2025

$$

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ACUS01 KWNS 301628
SWODY1
SPC AC 301626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Sat Aug 30 2025

Valid 301630Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF EASTERN NM...THE TX PANHANDLE...AND FAR WESTERN OK...

...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.

...Synopsis and Discussion...
Recent surface analysis places a pair of highs across the CONUS, one
over southern Lower MI and another in the eastern ID/southwest MT
vicinity. A reservoir of low-level moisture, characterized by
dewpoints above 60 deg F, exists between these two features, from
the southern CONUS up through the Plains. The low-level moisture
will help foster thunderstorm development over much of this area,
with the highest coverage anticipated along the surface troughing
that extends from a pair of surface lows over the central Plains
into the southern High Plains.

A belt of moderate west-northwesterly flow aloft will extend
eastward from eastern CO/far northeast NM across KS into the Ozarks.
Southern periphery of this stronger flow will help support moderate
effective bulk shear across northeast NM and the TX Panhandle/TX
South Plains. Despite residual cloud cover and poor lapse rates,
ample low-level moisture will help support modest buoyancy across
the region as well. The resulting environmental conditions may
result in a few stronger storms capable of hail (likely below 1" in
diameter) and/or damaging gusts.

..Mosier/Dean.. 08/30/2025

$$

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ACUS01 KWNS 301951
SWODY1
SPC AC 301949

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 PM CDT Sat Aug 30 2025

Valid 302000Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
SOUTHERN HIGH PLAINS...

...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.

...20Z Update...
No changes were made to the ongoing forecast. See the previous
discussion for additional information.

..Wendt.. 08/30/2025

.PREV DISCUSSION... /ISSUED 1126 AM CDT Sat Aug 30 2025/

...Synopsis and Discussion...
Recent surface analysis places a pair of highs across the CONUS, one
over southern Lower MI and another in the eastern ID/southwest MT
vicinity. A reservoir of low-level moisture, characterized by
dewpoints above 60 deg F, exists between these two features, from
the southern CONUS up through the Plains. The low-level moisture
will help foster thunderstorm development over much of this area,
with the highest coverage anticipated along the surface troughing
that extends from a pair of surface lows over the central Plains
into the southern High Plains.

A belt of moderate west-northwesterly flow aloft will extend
eastward from eastern CO/far northeast NM across KS into the Ozarks.
Southern periphery of this stronger flow will help support moderate
effective bulk shear across northeast NM and the TX Panhandle/TX
South Plains. Despite residual cloud cover and poor lapse rates,
ample low-level moisture will help support modest buoyancy across
the region as well. The resulting environmental conditions may
result in a few stronger storms capable of hail (likely below 1" in
diameter) and/or damaging gusts.

$$

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ACUS01 KWNS 310043
SWODY1
SPC AC 310041

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 PM CDT Sat Aug 30 2025

Valid 310100Z - 311200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Strong thunderstorms will be possible across parts of the southern
and central Plains this evening, but the chance for severe is low.

...DISCUSSION...
Northwesterly mid-level flow is evident on water vapor imagery over
much of the central and southern U.S. At the surface, a moist
airmass is in place over the southern and central Plains, where
dewpoints are mostly in the upper 60s and lower 70s F. Scattered
thunderstorms are ongoing across much of this airmass. Due to
relatively weak instability and deep-layer shear, along with limited large-scale ascent, any severe threat is expected to remain
extremely localized this evening. Elsewhere across the continental
U.S., no severe threat is expected this evening into tonight.

..Broyles.. 08/31/2025

$$

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ACUS01 KWNS 310600
SWODY1
SPC AC 310558

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Sun Aug 31 2025

Valid 311200Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few strong thunderstorms will be possible today across parts of
the southern and central Plains, and the the Pacific Northwest. The
severe potential appears to be low.

...DISCUSSION...
Mid-level northwesterly flow will be in place today in the central
U.S., as a moist airmass remains over much of the Great Plains. As
surface temperature warm, isolated to scattered thunderstorms will
develop over parts of the southern and central Plains this
afternoon. Although a few strong storms could occur, the combination
of instability and deep-layer shear will likely be too weak for an
appreciable severe weather threat. In the Pacific Northwest, a
mid-level low pressure system will affect western Washington, where
isolated thunderstorms could develop during the day. In the Pacific
Northwest, instability and deep-layer shear is also expected to be
insufficient for a severe threat. Elsewhere across the continental
United States, no severe threat is forecast today or tonight.

..Broyles/Thornton.. 08/31/2025

$$

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ACUS01 KWNS 311250
SWODY1
SPC AC 311249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Sun Aug 31 2025

Valid 311300Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Overall severe weather potential is expected to be low today and
tonight.

...Discussion...
Modest-strength mid-level northwesterly winds aloft will persist
over the Great Plains, to the east of the Rockies-centered upper
ridge and an upper low off the coastal Pacific Northwest. Weak convergence/subtle surface troughing will be prevalent in
association with a persistently moist air mass across the southern
Plains. Although a few strong storms could occur across parts of Kansas/Oklahoma into Texas this afternoon into evening, the
combination of only modest instability and relatively weak
deep-layer shear should limit the overall severe-weather potential.
A few strong storms could also develop across southwest New Mexico
and southeast Arizona later this afternoon into this evening, with
some stronger wind gusts a possibility.

..Guyer/Bentley.. 08/31/2025

$$

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ACUS01 KWNS 311619
SWODY1
SPC AC 311617

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1117 AM CDT Sun Aug 31 2025

Valid 311630Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Overall severe weather potential is expected to be low today and
tonight.

...Synopsis and Discussion...
Modest northwesterly flow aloft will persist today across the
central CONUS, which is situation between a developing Rex block
over southeast Canada and the northeast CONUS, and extensive upper
ridging from the Southwest through the northern Rockies. Recent
surface analysis shows moderate low-level moisture remains in place
over the Great Plains, MS Valley, and Southeast. This analysis also
placed a weak low along the central KS/OK border vicinity, with weak
troughing extending northward from this low into south-central NE
before arcing back northwestward through the NE Panhandle and
western Dakotas. Modest surface troughing also extends southwestward
from the low across the TX South Plains and into far southeast NM.

Thunderstorms are anticipated in the vicinity of this troughing from
the central Plains into southern High Plains, with additional
low-level moisture convergence contributing to continued
thunderstorms across much of central TX and southwest TX as well.
Limited buoyancy, owing to poor lapse rates and cool temperatures,
should temper the overall severe potential today.

Some evening and overnight thunderstorms are also possible across central/eastern WA, northern ID, and far northwest MT as ascent
attendant to a well-defined cyclone spreads into the region.

..Mosier/Lyons.. 08/31/2025

$$

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ACUS01 KWNS 311954
SWODY1
SPC AC 311953

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Sun Aug 31 2025

Valid 312000Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Overall severe weather potential is expected to be low today and
tonight.

...20Z Update...
The general thunderstorm forecast was adjusted based on
observational trends and recent guidance. See the previous
discussion for additional details.

..Wendt.. 08/31/2025

.PREV DISCUSSION... /ISSUED 1117 AM CDT Sun Aug 31 2025/

...Synopsis and Discussion...
Modest northwesterly flow aloft will persist today across the
central CONUS, which is situation between a developing Rex block
over southeast Canada and the northeast CONUS, and extensive upper
ridging from the Southwest through the northern Rockies. Recent
surface analysis shows moderate low-level moisture remains in place
over the Great Plains, MS Valley, and Southeast. This analysis also
placed a weak low along the central KS/OK border vicinity, with weak
troughing extending northward from this low into south-central NE
before arcing back northwestward through the NE Panhandle and
western Dakotas. Modest surface troughing also extends southwestward
from the low across the TX South Plains and into far southeast NM.

Thunderstorms are anticipated in the vicinity of this troughing from
the central Plains into southern High Plains, with additional
low-level moisture convergence contributing to continued
thunderstorms across much of central TX and southwest TX as well.
Limited buoyancy, owing to poor lapse rates and cool temperatures,
should temper the overall severe potential today.

Some evening and overnight thunderstorms are also possible across central/eastern WA, northern ID, and far northwest MT as ascent
attendant to a well-defined cyclone spreads into the region.

$$

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ACUS01 KWNS 010057
SWODY1
SPC AC 010055

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 PM CDT Sun Aug 31 2025

Valid 010100Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
No severe threat is expected across the continental U.S. this
evening and tonight.

...DISCUSSION...
Northwesterly flow is evident on water vapor imagery over much of
the central and southeastern U.S. At the surface, a large area of
high pressure is located from the Great Plains eastward into the
Appalachians. A moist airmass is in place from the Great Plains into
the Southeast. Isolated thunderstorms are ongoing across parts of
the Great Plains and southern Rockies. A few strong storms will be
possible this evening near an instability axis from west Texas into
central Oklahoma, but no appreciable severe threat is forecast.
Elsewhere across the continental U.S., no severe threat is expected
this evening and tonight.

..Broyles.. 09/01/2025

$$

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ACUS01 KWNS 010540
SWODY1
SPC AC 010538

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Mon Sep 01 2025

Valid 011200Z - 021200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The severe potential appears relatively low today across the
continental U.S., though a few strong storms will be possible across
parts of the Great Plains.

...DISCUSSION...
At mid-levels, a ridge will be in place across the western U.S.,
with northwesterly flow located from the Rockies eastward to the
Appalachians. A north-to-south corridor of low-level moisture will
present in the Great Plains, where warming surface heating will
contribute to scattered convective initiation. Throughout this
airmass, surface dewpoints will be mostly in the 60s with weak
instability developing by afternoon. Minimal deep-layer shear, poor
lapse rates and a lack of large-scale ascent will limit the severe
weather potential. Further west into the Pacific Northwest, a
mid-level low will remain offshore from the Washington Coast. An
axis of instability will develop across western Washington during
the day. Isolated thunderstorms will be possible in the afternoon,
but the environment should be insufficient for severe storms.
Elsewhere across the continental United States, no severe threat is
expected.

..Broyles/Moore.. 09/01/2025

$$

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ACUS01 KWNS 011253
SWODY1
SPC AC 011252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Mon Sep 01 2025

Valid 011300Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS...

...SUMMARY...
Isolated severe storms may occur across the southern Plains this
afternoon and early evening, including parts of southern Kansas and
western Oklahoma.

...Southern Plains including southern Kansas/western Oklahoma...
A shortwave trough centered over eastern Nebraska this morning will
progress southeastward toward the south-central Plains and
eventually the Ozarks by tonight. This will be in association with a strengthening belt of north-northwesterly mid-level winds (35 kt at
500 mb). While the related low-level/surface response will be muted,
a weak surface front/wind shift will progress southward from Kansas
into Oklahoma, with a relatively moist air mass preceding the
advancing front. Morning low clouds/stratus will abate by afternoon,
yielding to ample insolation and probably a corridor of moderate buoyancy/steepening lapse rates, particularly across southwest
Kansas/northwest Oklahoma. Increasing/widely scattered thunderstorm
development is probable into mid-afternoon near the front/wind shift
as the boundary layer warms. The enhanced north-northwesterly flow
aloft will contribute to 35+ kt effective shear, which could yield
some marginal supercells aside from evolving multicellular clusters.
Isolated instances of severe hail/damaging wind will be possible
through early evening as storms develop south-southeastward from
southern Kansas into western/northern Oklahoma.

..Guyer/Bentley.. 09/01/2025

$$

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ACUS01 KWNS 011624
SWODY1
SPC AC 011622

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Mon Sep 01 2025

Valid 011630Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN KANSAS INTO WESTERN/NORTHERN OKLAHOMA...

...SUMMARY...
Isolated severe thunderstorms may occur across parts of southern
Kansas and western/northern Oklahoma this afternoon and evening,
with isolated large hail and damaging winds the main threat.

...Southern/Central Plains...
A mid-level shortwave trough centered over eastern NE late this
morning will move southeastward toward the southern Plains and
Ozarks by tonight. This will occur in association with a belt of
modestly enhanced north-northwesterly mid-level winds (around 30-40
kt at 500 mb). While the related surface response will remain muted,
a weak surface front/wind shift will progress southward from KS into
OK, with a relatively moist air mass preceding the advancing
boundary. Ongoing low clouds/stratus should continue to gradually
erode this afternoon, yielding ample insolation and a corridor of
moderate instability and steepening low-level lapse rates,
particularly across southern KS into northwest OK. Widely scattered thunderstorm development is probable by mid/late afternoon near the
front/wind shift as the boundary layer warms. The enhanced
north-northwesterly flow aloft will contribute to 30-40 kt of
effective bulk shear, which should support multicell clusters and
perhaps marginal supercells. Isolated severe hail/damaging winds
will be possible through early evening as storms develop southward
from parts of southern KS into western/northern OK.

..Gleason/Lyons.. 09/01/2025

$$

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ACUS01 KWNS 011934
SWODY1
SPC AC 011933

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 PM CDT Mon Sep 01 2025

Valid 012000Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTHERN KANSAS
TO NORTHWEST OKLAHOMA...

...SUMMARY...
Isolated severe thunderstorms may occur across parts of southern
Kansas and western/northern Oklahoma this afternoon and evening,
with isolated large hail and damaging winds the main threats.

...20z Update...
The previous forecast remains on track with only minor adjustments
made to reflect recent convective trends. Initial thunderstorm
development along a weak surface front is noted from northeast to
southwest KS as of 19 UTC. Based on regional VWPs, mid-level flow
remains relatively strongest across southern to southwest KS on the west/southwest side of the upper wave, which should promote a
slightly higher potential for severe gusts and/or hail this
afternoon/evening. The Marginal risk area was slightly adjusted to
better capture this potential. See MCD #2025 for additional
short-term details.

Elsewhere, only minor adjustments to the thunder line were needed.
An occasional lightning flash or two will be possible during the
09-12 UTC period across central CA, but recent guidance continues to
suggest that lightning coverage/probability will likely remain below
10%.

..Moore.. 09/01/2025

.PREV DISCUSSION... /ISSUED 1122 AM CDT Mon Sep 01 2025/

...Southern/Central Plains...
A mid-level shortwave trough centered over eastern NE late this
morning will move southeastward toward the southern Plains and
Ozarks by tonight. This will occur in association with a belt of
modestly enhanced north-northwesterly mid-level winds (around 30-40
kt at 500 mb). While the related surface response will remain muted,
a weak surface front/wind shift will progress southward from KS into
OK, with a relatively moist air mass preceding the advancing
boundary. Ongoing low clouds/stratus should continue to gradually
erode this afternoon, yielding ample insolation and a corridor of
moderate instability and steepening low-level lapse rates,
particularly across southern KS into northwest OK. Widely scattered thunderstorm development is probable by mid/late afternoon near the
front/wind shift as the boundary layer warms. The enhanced
north-northwesterly flow aloft will contribute to 30-40 kt of
effective bulk shear, which should support multicell clusters and
perhaps marginal supercells. Isolated severe hail/damaging winds
will be possible through early evening as storms develop southward
from parts of southern KS into western/northern OK.

$$

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ACUS01 KWNS 020102
SWODY1
SPC AC 020100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Mon Sep 01 2025

Valid 020100Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS AND IN SOUTH-CENTRAL ARIZONA...

...SUMMARY...
Isolated severe thunderstorms may occur across parts of northern and
western Oklahoma this evening, with isolated large hail and damaging
winds the main threats. A marginal severe threat will also be
possible in parts of south-central Arizona.

...Northwest Oklahoma...
At mid-levels on water vapor imagery, a shortwave trough is moving
across the central U.S., embedded in northwesterly flow. At the
surface, a moist airmass is located in the southern and central
Plains with dewpoints in the lower to mid 60s F. The RAP has a
pocket of moderate instability over southern Kansas and northern
Oklahoma with MLCAPE estimated to be in the 1000 to 1500 J/kg range.
Isolated to scattered thunderstorms are ongoing within this pocket
of instability. These storms will persist for a couple more hours,
moving southeastward across parts of western and central Oklahoma.
RAP forecast soundings in north-central Oklahoma early this evening
have 0-6 km near 45 knots. In addition, the Oklahoma City 00Z
soundings has a somewhat steep lapse rates in the 0-3 km layer. This
suggests that isolated severe gust will be possible with the
stronger cells. Hail could also occur.

...Northeast North Dakota...
Northwesterly mid-level flow is evident on water vapor imagery over
parts of the northern Plains. At the surface, a moist airmass in
place with surface dewpoints in the lower to mid 60s F. Isolated
thunderstorms are ongoing near an axis of maximized low-level
convergence in northeastern North Dakota and far northwest
Minnesota. Although a strong storm will be possible this evening,
any severe threat is expected to be limited due to weak deep-layer
shear and poor lapse rates.

...South-central Arizona...
Water vapor imagery shows a plume of mid-level moisture over
south-central Arizona. A few thunderstorms are ongoing within this
plume in the Phoenix area. This convection is located within a
pocket of instability, where SBCAPE values are estimated in the 1000
to 1500 J/kg range, according to the RAP. The 00Z sounding at Tuscon
has a surface dewpoints of 55 F, with 0-3 km lapse rates of 9.7
C/km, with a dry adiabatic temperature profile from the surface to
700 mb. This should be favorable for isolated severe gusts with the
stronger cells for another hour or two.

..Broyles.. 09/02/2025

$$

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ACUS01 KWNS 020543
SWODY1
SPC AC 020542

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1242 AM CDT Tue Sep 02 2025

Valid 021200Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Thunderstorms with potential for isolated severe wind gusts and hail
will be possible today across parts of the northern Plains and upper Mississippi Valley.

...Northern Plains/Upper Mississippi Valley...
North-northwesterly mid-level flow will continue across the Great
Plains today, as a shortwave trough moves into the upper Mississippi
Valley. At the surface, a cold front will advance southeastward
across the northern Plains and upper Mississippi Valley. Ahead of
the front, surface dewpoints in the lower to mid 60s F will
contribute to the development of moderate instability by afternoon.
As surface temperatures warm and low-level convergence becomes
maximized along and ahead of the front, scattered convective
initiation will be likely during the mid to late afternoon.
Thunderstorms are expected to form and move southeastward across
eastern South Dakota and central to southern Minnesota. Most late
afternoon forecast soundings across that area by late afternoon have
0-6 km shear around 25 knots, with steep lapse rates between the
surface and 850 mb. This should be sufficient for a marginal severe
threat. The stronger multicells could be associated with isolated
severe wind gusts and hail.

..Broyles/Thornton.. 09/02/2025

$$

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ACUS01 KWNS 021234
SWODY1
SPC AC 021233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Tue Sep 02 2025

Valid 021300Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE UPPER MIDWEST...

...SUMMARY...
Thunderstorms with potential for isolated severe wind gusts and
marginally severe hail will be possible this afternoon into the
early evening across parts of the Upper Midwest.

...Upper Midwest...
An upper trough initially over central Canada will dig southeastward
into the Upper Midwest/Lake Superior vicinity during the period.
Showers and weak thunderstorms ongoing this morning over MN, aided
by an MCV over northern MN, will gradually dissipate with
differential heating/residual outflow arcing from southern MN west-northwestward towards the Dakotas/MN border by mid afternoon.
A cold front initially over ND will advance southeastward
into an adequately moist airmass, featuring surface dewpoints in the
lower to mid 60s F ahead of it. Diurnal heating will likely yield
moderate SBCAPE (1500-2000 J/kg) ahead of the front by mid-late
afternoon. Model guidance is consistent in showing a band of
scattered thunderstorms developing from the eastern half of SD into
central MN by the mid-late afternoon. Upscale growth with higher
storm coverage is expected from near the MN/SD border eastward into
central and southern MN during the 22-02 UTC period. The stronger
mid- and upper-level flow will likely lag behind the surface front
and limit effective shear magnitudes (at or below 25 kt). However,
a few organized multicells could be associated with isolated severe
wind gusts and hail before this activity subsides during the
early-mid evening.

..Smith/Bentley.. 09/02/2025

$$

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ACUS01 KWNS 021627
SWODY1
SPC AC 021625

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Tue Sep 02 2025

Valid 021630Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN SOUTH DAKOTA INTO SOUTHERN/CENTRAL MINNESOTA AND FAR
NORTHWESTERN WISCONSIN...

...SUMMARY...
Thunderstorms capable of producing isolated severe wind gusts and
marginally severe hail will be possible this afternoon and evening
across parts of the northern Plains and Upper Midwest.

...Northern Plains/Upper Midwest...
An upper trough over central Canada late this morning will dig
southeastward towards the Upper Midwest/Lake Superior vicinity
through the period. Showers and weak thunderstorms are ongoing over
parts of central MN, aided by a remnant MCV over northern MN. This
activity is forecast to further weaken this afternoon, with a
residual outflow boundary arcing from southern MN west-northwestward
towards the SD/MN border by mid afternoon. A cold front over ND will
continue to advance southeastward into an adequately moist low-level
airmass, with surface dewpoints generally in the lower to mid 60s.
Filtered daytime heating away from this morning's convective cloud
debris, along with modestly steepened mid-level lapse rates
(reference 12Z ABR sounding), should aid in weak to locally moderate instability (MLCAPE around 1000-2000 J/kg) developing ahead of the
front by mid to late afternoon.

Latest model guidance remains consistent in showing isolated to
scattered thunderstorms developing across roughly the eastern third
of SD into central MN this afternoon along/near the cold front.
There is considerable uncertainty regarding the degree of
instability that will develop and related thunderstorm intensity
given the widespread cloud cover in south-central MN. The stronger mid/upper-level flow associated with the upper trough over Canada
will likely lag behind the surface front to some extent. This should
limit effective bulk shear magnitudes (up to 20-30 kt). Even so,
modestly organized multicells associated with isolated severe wind
gusts and marginally severe hail appear possible, before this
activity eventually subsides this evening with the loss of daytime
heating. The Marginal Risk has been adjusted to account for the
latest observational/short-term guidance trends.

...Lower Colorado River Valley...
Compared to yesterday, modestly enhanced mid-level flow should trend
more south-southeasterly today as a weak shortwave trough lifts
northward from Baja California into the lower CO River Valley. Associated/ongoing showers and thunderstorms across southern CA
should generally remain sub-severe through the morning as they track northwestward. In the wake of this activity, there is a fair amount
of uncertainty regarding destabilization potential given scattered
to widespread cloudiness over much of the lower CO River Valley.
Wherever cloud breaks and heating can occur, steepening low-level
lapse rates may support strong/gusty winds with any convection that
can develop. Still, the potential for a focused area of severe gusts
appears too low to include any probabilities at this time.

..Gleason/Lyons.. 09/02/2025

$$

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ACUS01 KWNS 021959
SWODY1
SPC AC 021958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Tue Sep 02 2025

Valid 022000Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN SOUTH DAKOTA INTO SOUTHERN/CENTRAL MINNESOTA AND FAR
NORTHWESTERN WISCONSIN...

...SUMMARY...
Thunderstorms capable of producing isolated severe wind gusts and
marginally severe hail will be possible this afternoon and evening
across parts of the northern Plains and Upper Midwest.

...20Z Update...
No changes were made to the ongoing forecast. Strong to marginally
severe storms still appear possible along a cold front in the
northern Plains/Upper Midwest. See the previous discussion for
additional details.

..Wendt.. 09/02/2025

.PREV DISCUSSION... /ISSUED 1125 AM CDT Tue Sep 02 2025/

...Northern Plains/Upper Midwest...
An upper trough over central Canada late this morning will dig
southeastward towards the Upper Midwest/Lake Superior vicinity
through the period. Showers and weak thunderstorms are ongoing over
parts of central MN, aided by a remnant MCV over northern MN. This
activity is forecast to further weaken this afternoon, with a
residual outflow boundary arcing from southern MN west-northwestward
towards the SD/MN border by mid afternoon. A cold front over ND will
continue to advance southeastward into an adequately moist low-level
airmass, with surface dewpoints generally in the lower to mid 60s.
Filtered daytime heating away from this morning's convective cloud
debris, along with modestly steepened mid-level lapse rates
(reference 12Z ABR sounding), should aid in weak to locally moderate instability (MLCAPE around 1000-2000 J/kg) developing ahead of the
front by mid to late afternoon.

Latest model guidance remains consistent in showing isolated to
scattered thunderstorms developing across roughly the eastern third
of SD into central MN this afternoon along/near the cold front.
There is considerable uncertainty regarding the degree of
instability that will develop and related thunderstorm intensity
given the widespread cloud cover in south-central MN. The stronger mid/upper-level flow associated with the upper trough over Canada
will likely lag behind the surface front to some extent. This should
limit effective bulk shear magnitudes (up to 20-30 kt). Even so,
modestly organized multicells associated with isolated severe wind
gusts and marginally severe hail appear possible, before this
activity eventually subsides this evening with the loss of daytime
heating. The Marginal Risk has been adjusted to account for the
latest observational/short-term guidance trends.

...Lower Colorado River Valley...
Compared to yesterday, modestly enhanced mid-level flow should trend
more south-southeasterly today as a weak shortwave trough lifts
northward from Baja California into the lower CO River Valley. Associated/ongoing showers and thunderstorms across southern CA
should generally remain sub-severe through the morning as they track northwestward. In the wake of this activity, there is a fair amount
of uncertainty regarding destabilization potential given scattered
to widespread cloudiness over much of the lower CO River Valley.
Wherever cloud breaks and heating can occur, steepening low-level
lapse rates may support strong/gusty winds with any convection that
can develop. Still, the potential for a focused area of severe gusts
appears too low to include any probabilities at this time.

$$

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ACUS01 KWNS 030538
SWODY1
SPC AC 030536

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1236 AM CDT Wed Sep 03 2025

Valid 031200Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered thunderstorms with potential for large to very large hail
and severe wind gusts are expected this afternoon and evening across
parts of the central Plains and lower Missouri Valley.

...Central Plains/Lower Missouri Valley...
At mid-levels, heights will fall over much of the central U.S., as a
low moves southward toward the western Great Lakes and as a
shortwave trough moves through the Upper Midwest. At the surface, a
cold front will advance southward across the central Plains and
lower Missouri Valley. Ahead of the front, surface dewpoints in the
60s F will contribute to a pocket of moderate instability by
afternoon. Warming surface temperatures and increasing low-level
convergence near the front will support scattered thunderstorm
development along the northern edge of the stronger instability this
afternoon. These storms will become organized and move
south-southeastward across central and eastern Kansas, and western
Missouri during the late afternoon and early to mid evening.

RAP forecast soundings near the instability axis across east-central
Kansas late this afternoon have MLCAPE peaking in the 2000 to 2500
J/kg range, with steep lapse rates in the low to mid-levels. 0-6 km
shear is forecast to be near 45 knots, due to a combination of speed
shear and directional shear from the surface to about 600 mb. This
environment will support large hail with supercells. Moderate
deep-layer shear and mid-level lapse rates near 7.5 C/km will
support a potential for hailstones greater than 2 inches in diameter
with the more intense updrafts. Isolated severe wind gusts will also
be possible with supercells, or with bowing line segments that
develop out of merging cells. The severe threat is expected to
persist into the mid evening, as several small clusters move
southeastward into southeast Kansas and southwest Missouri.

..Broyles/Thornton.. 09/03/2025

$$

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ACUS01 KWNS 030057
SWODY1
SPC AC 030055

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 PM CDT Tue Sep 02 2025

Valid 030100Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSOURI VALLEY...

...SUMMARY...
Thunderstorms with isolated severe gusts and hail will be possible
early this evening across parts of the mid Missouri Valley.

...Mid Missouri Valley...
Northwest mid-level flow is evident on water vapor imagery from the
Great Plains into the Mississippi Valley. At the surface, a cold
front is moving through the north-central U.S. Ahead of the front,
surface dewpoints are in the mid 60s F, and the RAP has an axis of
moderate instability from central Nebraska into western Minnesota.
Isolated strong storms are ongoing near this axis of instability.
Near the storms, the Sioux Falls WSR-88D VWP has 0-6 km shear near
35 knots, mostly due to speed shear in the mid-levels. This may be
enough for an isolated severe threat over the next hour or two in
the vicinity of Sioux Falls, South Dakota and Sioux City, Iowa. The
primary threats will be marginally severe wind gusts and hail.

..Broyles.. 09/03/2025

$$

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ACUS01 KWNS 031158
SWODY1
SPC AC 031157

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0657 AM CDT Wed Sep 03 2025

Valid 031300Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KANSAS INTO WESTERN MISSOURI...

...SUMMARY...
Scattered thunderstorms with potential for large to very large hail
and severe wind gusts are expected this afternoon and evening across
parts of the central Plains and lower Missouri Valley.

...Central Plains/Lower Missouri Valley...
Water-vapor imagery this morning shows a mid-level shortwave trough
over southern SD moving quickly southeast as a larger-scale mid- to
upper-level low moves from western ON to near Lake Superior during
the period. The smaller-scale disturbance is forecast to reach the
lower MO Valley by late afternoon with an attendant belt of
moderately strong northwesterly mid- to high-level flow
overspreading the central Plains into the mid MS Valley.

In the low levels, a cold front will advance southward across the
central Plains and lower Missouri Valley with 60s deg F surface
dewpoints ahead of the boundary. Diurnal heating will contribute to
moderate buoyancy by mid afternoon with convective inhibition
eroding near the front. Scattered thunderstorms are forecast to
develop from central KS eastward into the lower MO Valley during the
20-00 UTC period.

The aforementioned strong northwesterly flow in the 500 to 300 mb
layer (35-55 kt) will yield effective shear supporting organized
updrafts. A few supercells will probably evolve across KS and
perhaps into western MO where the main risk will be large to very
large hail. Severe wind gusts will also be possible with
supercells, or small clusters/bowing segments where 0-2 km lapse
rates are steepest (i.e., KS). The severe threat is expected to
persist into the mid evening as several small clusters move
southeastward into southeast Kansas and adjacent portions of
northern OK and southwest Missouri.

..Smith/Bentley.. 09/03/2025

$$

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ACUS01 KWNS 031630
SWODY1
SPC AC 031628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Sep 03 2025

Valid 031630Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered thunderstorms capable of producing large to very large
hail and severe wind gusts should occur this afternoon and evening
across parts of the central Plains and lower Missouri Valley.

...Central Plains into the Lower Missouri Valley...
A mid-level shortwave trough over southern SD/eastern NE will
continue to advance quickly southeastward today as a large-scale
upper-level low moves from western ON to near Lake Superior through
the period. The shortwave trough is forecast to reach the lower MO
Valley by late afternoon, with an attendant belt of moderately
strong northwesterly mid/high-level flow overspreading the central
Plains into the mid MS Valley. At the surface, a cold front will
advance southward across parts of the central Plains and lower MO
Valley, with generally low to mid 60s surface dewpoints present
ahead of the boundary. Diurnal heating of this airmass will
contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by
mid afternoon across central/eastern KS, with weaker instability
forecast with eastward extent into MO. As convective inhibition
gradually erodes near the front, scattered thunderstorms will likely
develop along its length from central KS into the lower MO Valley
during the 20-00Z period.

Around 35-55 kt of northwesterly flow in the 500-250 mb layer will
yield similar values of effective bulk shear, which will support
organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk
will be large to very large hail given steep lapse rates aloft and
favorable shear. Severe wind gusts will also be possible with these
supercells, or any small clusters/bowing segments that can develop
where low-level lapse rates are steepest (mainly KS into northwest
OK and parts of the OK/TX Panhandles). Some severe threat should
persist into the evening as multiple small clusters move southward
into southern KS and adjacent portions of far northern OK and
southwest MO, before they eventually weaken as convective inhibition
increases with nocturnal cooling.

...Great Lakes/Midwest...
Additional thunderstorms should develop this afternoon along/near
the cold front across parts of Lower MI into central IL. Poor lapse
rates aloft and limited low-level moisture (reference 12Z soundings
from APX and ILX) will likely temper the degree of instability that
can develop, even with diurnal heating. While occasional
strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe
threat should remain fairly limited.

..Gleason/Lyons.. 09/03/2025

$$

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ACUS01 KWNS 031957
SWODY1
SPC AC 031956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Wed Sep 03 2025

Valid 032000Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered thunderstorms capable of producing large to very large
hail and severe wind gusts should occur this afternoon and evening
across parts of the central Plains and lower Missouri Valley.

...20Z Update...
The general thunderstorm forecast was updated based on observational
trends. The severe probabilities remain unchanged. See the previous
forecast for additional information.

..Wendt.. 09/03/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Sep 03 2025/

...Central Plains into the Lower Missouri Valley...
A mid-level shortwave trough over southern SD/eastern NE will
continue to advance quickly southeastward today as a large-scale
upper-level low moves from western ON to near Lake Superior through
the period. The shortwave trough is forecast to reach the lower MO
Valley by late afternoon, with an attendant belt of moderately
strong northwesterly mid/high-level flow overspreading the central
Plains into the mid MS Valley. At the surface, a cold front will
advance southward across parts of the central Plains and lower MO
Valley, with generally low to mid 60s surface dewpoints present
ahead of the boundary. Diurnal heating of this airmass will
contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by
mid afternoon across central/eastern KS, with weaker instability
forecast with eastward extent into MO. As convective inhibition
gradually erodes near the front, scattered thunderstorms will likely
develop along its length from central KS into the lower MO Valley
during the 20-00Z period.

Around 35-55 kt of northwesterly flow in the 500-250 mb layer will
yield similar values of effective bulk shear, which will support
organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk
will be large to very large hail given steep lapse rates aloft and
favorable shear. Severe wind gusts will also be possible with these
supercells, or any small clusters/bowing segments that can develop
where low-level lapse rates are steepest (mainly KS into northwest
OK and parts of the OK/TX Panhandles). Some severe threat should
persist into the evening as multiple small clusters move southward
into southern KS and adjacent portions of far northern OK and
southwest MO, before they eventually weaken as convective inhibition
increases with nocturnal cooling.

...Great Lakes/Midwest...
Additional thunderstorms should develop this afternoon along/near
the cold front across parts of Lower MI into central IL. Poor lapse
rates aloft and limited low-level moisture (reference 12Z soundings
from APX and ILX) will likely temper the degree of instability that
can develop, even with diurnal heating. While occasional
strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe
threat should remain fairly limited.

$$

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ACUS01 KWNS 040052
SWODY1
SPC AC 040051

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 PM CDT Wed Sep 03 2025

Valid 040100Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN SOUTH-CENTRAL
KS...

...SUMMARY...
Isolated large hail remains possible across mainly southern Kansas
this evening.

...KS/MO/OK...
Large to very large hail up to 3 inches in diameter was prolific in
several early-evening supercells across east-central KS. This has
recently become confined to the I-135/35 corridors into
south-central KS. These cells should wane over the next couple hours
with rapidly increasing nocturnal MLCIN. Widely scattered elevated
convection may persist along and to the rear of the undercutting, southward-sagging surface cold front. Adequate speed shear within
the northwesterly mid to upper flow regime may pose a threat for
small to marginally severe hail across southern MO through early
tonight.

..Grams.. 09/04/2025

$$

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ACUS01 KWNS 040552
SWODY1
SPC AC 040550

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Thu Sep 04 2025

Valid 041200Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
EAST...

...SUMMARY...
Isolated damaging winds are possible across parts of the Northeast
to the southern Appalachians and Tennessee Valley from late morning
through the afternoon.

...Synopsis...
A vertically stacked cyclone will drift north in northern ON, as an
intense mid-level jetlet and shortwave trough amplifies from the
southern Canadian Prairies across the Upper Midwest/Great Lakes. A
leading cold front will progress east into the Northeast to TN
Valley by this afternoon, with a separate lee trough diurnally
sharpening from VA into NY.

...Southern Appalachians/TN Valley to the Northeast...
Convection will likely be ongoing at 12Z along parts of the
aforementioned cold front from the Lake Erie to northern KY
vicinity. Despite weak mid-level lapse rates, diabatic surface
heating ahead of this activity should yield diurnal increases in
convective coverage/intensity by late morning across parts of the
Cumberland Plateau. This will overlap the northern extent of
moderate buoyancy across the TN Valley where low-level moisture is
richer. Combined with a more westerly component to mid-level flow
near the basal portion of the broad trough, a few semi-discrete and
loosely organized cells should develop southward during the
afternoon. Locally damaging winds and marginally severe hail are
possible, centered on the eastern TN vicinity.

Isolated to scattered multicell clusters and short-line segments may
also evolve in the afternoon from convection along/ahead of the cold
front and lee trough. Weak MLCAPE and poor mid-level lapse rates
will temper convective vigor, with damaging wind potential locally
augmented where pockets of deeper boundary-layer heating occur.

...Mid-MO Valley...
The aforementioned shortwave trough and intense mid-level jetlet
amplifying into the Upper Midwest could support a couple brief
strong storms in the early evening. A narrow corridor of meager
surface-based buoyancy may develop ahead of a sharpening cold front
by late afternoon. Modified moisture return in the wake of a prior
frontal passage will be limited and convection should remain
low-topped given the flimsy buoyancy. Still, the background wind
fields and strengthening forcing for ascent render concern for a few
locally strong gusts and small hail.

...KS...
An accelerating and sharpening cold front will sweep south across
the central High/Great Plains tonight. Undercut/elevated convection
should form to the cold side of this boundary early Friday morning.
Locally strong surface gusts may accompany this activity amid robust
low-level northerlies.

..Grams/Thornton.. 09/04/2025

$$

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ACUS01 KWNS 041233
SWODY1
SPC AC 041231

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 AM CDT Thu Sep 04 2025

Valid 041300Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
EAST AND THE MIDDLE MISSOURI VALLEY...

...SUMMARY...
Isolated damaging winds are possible across parts of the Northeast
to the southern Appalachians and Tennessee Valley from late morning
through the afternoon. Isolated severe gusts are possible across
parts of the middle Missouri Valley late this afternoon into the
early evening.

...Southern Appalachians/TN Valley to the Northeast...
Isolated to scattered showers/thunderstorms are ongoing this morning
from the Lower Great Lakes southward into the southern Appalachians. Water-vapor imagery shows a vertically stacked cyclone over Ontario
with a disturbance rotating through the basal portion of the larger
scale trough. This mid-level feature will quickly move from the
upper OH Valley into the NY/central Appalachians by the late
afternoon.

Despite weak mid-level lapse rates, some diurnal heating ahead of
this activity should yield gradual intensification of thunderstorms
and increased storm coverage by late morning across parts of the
southern Appalachians. Locally damaging winds and marginally severe
hail are possible, centered on the eastern TN vicinity.

Isolated to scattered multicell clusters and short-line segments may
also evolve in the afternoon from convection along/ahead of the cold
front and lee trough. Weak MLCAPE and poor mid-level lapse rates
will temper convective vigor, with damaging wind potential locally
augmented to where pockets of deeper boundary-layer heating occur.

...Mid-MO Valley...
An intense mid-level speed max/shortwave trough will quickly move
from the southern part of the Prairie provinces into the mid MO
Valley by this afternoon, before moving into the southwest Great
Lakes by early Friday morning. Some model spread exists on the
magnitude of destabilization immediately ahead of a cold front
forecast to sweep through the region late this afternoon into the
evening. However, weak buoyancy appears likely to develop and
low-level lapse rates may become adequately steep to support a
narrow corridor of low-topped storms capable of isolated severe
gusts.

...KS...
An accelerating and sharpening cold front will sweep south across
the central High/Great Plains tonight. Undercut/elevated convection
should form to the cold side of this boundary early Friday morning.
Locally strong surface gusts may accompany this activity amid robust
low-level northerlies.

..Smith/Bentley.. 09/04/2025

$$

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ACUS01 KWNS 041626
SWODY1
SPC AC 041624

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1124 AM CDT Thu Sep 04 2025

Valid 041630Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS
OF THE MID MISSOURI VALLEY...

...SUMMARY...
Isolated damaging winds may occur across parts of New York to the
Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe
gusts are also possible across parts of the mid Missouri Valley late
this afternoon and early evening.

...New York into the Mid-Atlantic and Tennessee Valley...
A closed mid/upper-level low will remain centered over Ontario
today. Multiple mid-level perturbations will rotate around this
feature through the period, including a shortwave trough forecast to
advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and
thunderstorms are ongoing mainly ahead of a surface cold front from
parts of western NY southward to the TN Valley in a low/mid-level
moisture plume. Generally clear skies ahead of this activity should
allow for ample daytime heating of a modestly moistened low-level
airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO
show rather poor mid-level lapse rates, which will likely hinder
updraft strength even as weak instability develops this afternoon
with continued diurnal heating.

Modestly enhanced southwesterly low/mid-level flow should still aid
in some thunderstorm organization even with the apparent
thermodynamic limitations, with multicells the dominant convective
mode. Wherever low-level lapse rates can become steepened, a risk
for at least isolated damaging winds remains apparent. Some hail may
also occur with the strongest cores across parts of the TN
Valley/southern Appalachians where locally greater instability
should be present this afternoon. The Marginal Risk has been
adjusted for ongoing trends, but the potential for a more focused
corridor of scattered severe/damaging winds remains unclear.

...Mid Missouri Valley...
A mid-level shortwave trough and attendant strong speed maximum will
move quickly southeastward today from central Canada and the
northern Plains towards the mid MO Valley and vicinity. Pronounced
ascent associated with this jet should encourage convection to
develop by late this afternoon across parts of eastern SD and
vicinity. While low-level moisture and MLCAPE are both expected to
remain very limited, enhanced low/mid-level northwesterly flow may
still support some risk for severe gusts with any low-topped
convection that can develop and spread quickly southeastward before
weakening this evening with the loss of daytime heating.

...Kansas...
A sharp cold front will sweep southward across the central Plains
tonight. Elevated convection should form to the cool side of this
boundary late tonight through early Friday morning given sufficient
MUCAPE. Locally strong surface gusts and small hail may accompany
this activity amid robust low-level northerlies, but the overall
severe potential should remain fairly low given the tendency for
convection to be mostly elevated.

...Arizona/Lower Colorado River Valley...
Thunderstorms should develop again today across parts of
central/southern AZ and the lower CO River Valley, beneath weak
mid-level flow and on the periphery of increasing mid-level moisture
associated with Tropical Storm Lorena. Weak shear should keep
thunderstorms mostly disorganized, but occasional strong/gusty winds
may occur where low-level lapse rates can become steepened.

..Gleason/Lyons.. 09/04/2025

$$

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ACUS01 KWNS 042000
SWODY1
SPC AC 041959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Thu Sep 04 2025

Valid 042000Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
NEW YORK...TO THE MID ATLANTIC...SOUTHERN APPALACHIANS AND MID
MISSOURI VALLEY...

...SUMMARY...
Isolated damaging gusts remain possible across parts of New York to
the Mid-Atlantic and Southern Appalachians through early this
evening. Isolated severe gusts are also possible across parts of the
mid Missouri Valley late this afternoon and early evening.

...20z Update Mid Atlantic and southern Appalachians...
Several clusters of strong to severe thunderstorms have matured and
are expected to continue through early this evening along and ahead
of the slow-moving cold front from the Mid Atlantic southward.
Despite poor mid-level lapse rates, heating of the modestly moist
air mass is supporting around 500-1000 J/kg of MLCAPE, sufficient
for a few stronger updrafts. As convection gradually increases in
coverage through the remainder of this afternoon, clustering and
30-40 kt of mid-level flow will continue to support isolated
damaging gust potential into early this evening. Some hail remains
possible with the more cellular elements, especially father
southwest over the eastern TN Valley where storm coverage should
remain more isolated. The primary change was to align the western
edge of the MRGL and severe probabilities with current frontal
position, and shift them slightly east for ongoing storms on the
border of NC and southern VA.

...New York...
As the line of showers and weak thunderstorms continues eastward
along the front, occasional damaging gusts remain possible owing to
mixing of stronger mid-level flow downward this afternoon. Some
heating, but marginal surface moisture should keep buoyancy and the
resulting updrafts weak. With MLCAPE generally less than 500 J/kg,
showers and storms should steadily weaken with the loss of diurnal
heating. The MRGL risk area has been trimmed behind the ongoing
line. Otherwise, the prior outlook remains unchanged, see the
previous discussion.

..Lyons.. 09/04/2025

.PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Sep 04 2025/

...New York into the Mid-Atlantic and Tennessee Valley...
A closed mid/upper-level low will remain centered over Ontario
today. Multiple mid-level perturbations will rotate around this
feature through the period, including a shortwave trough forecast to
advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and
thunderstorms are ongoing mainly ahead of a surface cold front from
parts of western NY southward to the TN Valley in a low/mid-level
moisture plume. Generally clear skies ahead of this activity should
allow for ample daytime heating of a modestly moistened low-level
airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO
show rather poor mid-level lapse rates, which will likely hinder
updraft strength even as weak instability develops this afternoon
with continued diurnal heating.

Modestly enhanced southwesterly low/mid-level flow should still aid
in some thunderstorm organization even with the apparent
thermodynamic limitations, with multicells the dominant convective
mode. Wherever low-level lapse rates can become steepened, a risk
for at least isolated damaging winds remains apparent. Some hail may
also occur with the strongest cores across parts of the TN
Valley/southern Appalachians where locally greater instability
should be present this afternoon. The Marginal Risk has been
adjusted for ongoing trends, but the potential for a more focused
corridor of scattered severe/damaging winds remains unclear.

...Mid Missouri Valley...
A mid-level shortwave trough and attendant strong speed maximum will
move quickly southeastward today from central Canada and the
northern Plains towards the mid MO Valley and vicinity. Pronounced
ascent associated with this jet should encourage convection to
develop by late this afternoon across parts of eastern SD and
vicinity. While low-level moisture and MLCAPE are both expected to
remain very limited, enhanced low/mid-level northwesterly flow may
still support some risk for severe gusts with any low-topped
convection that can develop and spread quickly southeastward before
weakening this evening with the loss of daytime heating.

...Kansas...
A sharp cold front will sweep southward across the central Plains
tonight. Elevated convection should form to the cool side of this
boundary late tonight through early Friday morning given sufficient
MUCAPE. Locally strong surface gusts and small hail may accompany
this activity amid robust low-level northerlies, but the overall
severe potential should remain fairly low given the tendency for
convection to be mostly elevated.

...Arizona/Lower Colorado River Valley...
Thunderstorms should develop again today across parts of
central/southern AZ and the lower CO River Valley, beneath weak
mid-level flow and on the periphery of increasing mid-level moisture
associated with Tropical Storm Lorena. Weak shear should keep
thunderstorms mostly disorganized, but occasional strong/gusty winds
may occur where low-level lapse rates can become steepened.

$$

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ACUS01 KWNS 050049
SWODY1
SPC AC 050047

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0747 PM CDT Thu Sep 04 2025

Valid 050100Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not expected tonight.

...Southwest/south-central KS...
A sharpening cold front will sweep southward across KS tonight.
Mostly elevated convection should increase to the cool side of this undercutting boundary, mainly during the early morning/pre-dawn
hours. Initially steep mid-level lapse rates and adequate MUCAPE
could support a few storms capable of producing small hail and
locally strong gusts amid strengthening low-level northerlies.
Overall severe potential still appears fairly low.

..Grams.. 09/05/2025

$$

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ACUS01 KWNS 050540
SWODY1
SPC AC 050539

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Fri Sep 05 2025

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE BORDER
AREAS OF TN/MS/AL TO WV/OH...

...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two are possible from the Upper Ohio to Tennessee Valleys during
the late afternoon and evening.

...Upper OH to TN Valleys...
Neutral mid-level height change and initially weak convergence along
a slow-moving cold front should delay diurnal convective
development. But eastward progression of a low-amplitude impulse,
currently over western KS, and strengthening low-level convergence
should yield scattered thunderstorms in the late afternoon to early
evening. The bulk of strong mid-level flow will largely lag behind
the portion of the front that is south of the Upper OH Valley. But
with the late day timing of storms, an extensive plume of moderate
buoyancy should be prevalent ahead of it. Several multicell clusters
and transient supercell structures should develop during the evening
within the moderately sheared, southwesterly flow regime. Scattered
damaging winds will be the primary hazard, with isolated severe hail
and a brief tornado also possible. The severe threat will diminish
towards late evening given the extensive overturning and lack of
stronger low-level flow/shear to sustain the threat overnight.

...North TX to Mid-South...
An elongated mid-level thermal trough, characterized by 500-mb
temperatures of -10 to -12 C, will extend into north TX, well to the
south of a persistent vertically stacked cyclone over northern ON.
Most guidance suggests low to mid-level wind fields will be modest
and contain veer-back-veer signatures. Strong speed shear should be
mainly confined above 500 mb, coincident with poor upper-level lapse
rates atop steeper mid-level lapse rates. Consensus of CAM guidance
suggests a messy convective mode should be common as convection
increases in the late afternoon and evening, along the more
west/east-oriented portion of the surface cold front. Given these
factors, have maintained a level 1-MRGL risk for an isolated severe
hail/wind threat with a southward shift based on latest guidance.

..Grams/Squitieri.. 09/05/2025

$$

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ACUS01 KWNS 051211
SWODY1
SPC AC 051209

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0709 AM CDT Fri Sep 05 2025

Valid 051300Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE TENNESSEE VALLEY AND UPPER OHIO VALLEY...

...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two are possible from the Upper Ohio to Tennessee Valleys during
the late afternoon and evening.

...Upper OH to TN Valleys...
Water-vapor imagery shows a large gyre centered over Ontario and
cyclonic flow over much of eastern North America. A series of
mid-level disturbances/speed maxima will rotate through its base
during the Day-1 period, and there are two lead impulses over the
St. Lawrence Seaway and the Upper Great Lakes this morning. A
weaker impulse associated with convection early this morning over KS
will rapidly move east into the northern part of the OH Valley
through this evening and immediately ahead of a more notable
shortwave trough moving southeast from the Dakotas into the Great
Lakes.

A cold front oriented mostly north-south over the Great Lakes from a
surface low will push east during the day, while the trailing
southern portion of the boundary that is west-east oriented,
gradually pushes south and eventually overtakes a residual frontal
segment.

Heating ahead of the aforementioned low-amplitude impulse and
strengthening low-level convergence along the boundary will likely
yield scattered to numerous showers/thunderstorms developing in the
late afternoon to early evening. Much of the stronger mid-level
flow will remain spatially displaced from the warm sector in the
post-frontal airmass except over the Upper OH Valley. Moderate
buoyancy will favor strong to severe multicells and some supercells
(where shear is stronger). Isolated severe gusts (55-70 mph) seem
probable which will result in scattered wind damage accompanying the
stronger thunderstorm cores and line segments. Models differ on the
character of mixing and hodograph size over the southeast OH/WV
portion of the Slight Risk, but low-tornado potential may be
greatest here compared to farther south/southwest over the TN
Valley. The severe threat will diminish towards late evening given
the extensive overturning and lack of stronger low-level flow/shear
to sustain the threat overnight.

...North TX to Mid-South...
An elongated mid-level thermal trough, characterized by 500-mb
temperatures of -10 to -12 C, will extend into north TX, well to the
south of a persistent vertically stacked cyclone over northern
Ontario. A copious amount of high cloud cover will tend to result
in high-level lapse rates becoming weaker during the period. Model
data implies a messy storm mode as isolated to locally scattered
storm coverage ensues during the late afternoon/evening. An
isolated wind/hail risk may accompany the stronger storms.

..Smith/Broyles.. 09/05/2025

$$

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ACUS01 KWNS 051631
SWODY1
SPC AC 051630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Fri Sep 05 2025

Valid 051630Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE TENNESSEE VALLEY AND UPPER OHIO VALLEY...

...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two are possible from the Upper Ohio to Tennessee Valleys, mainly
late this afternoon and evening.

...Ohio Valley/Central Appalachians to the Tennessee Valley...
A large-scale upper trough/low will remain centered over Ontario
today, with mid/upper-level troughing extending southward across
much of the Great Lakes/Midwest into the OH Valley. A cold front
will continue to advance slowly southeastward across portions of the
Mid-South and OH Valley through this evening. Daytime heating of a
seasonably moist low-level airmass ahead of this front over the TN
Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late
afternoon, mainly in KY/TN. Weaker instability is forecast with
northward extent into the upper OH Valley and central Appalachians.

Forcing for ascent aloft will remain nebulous for much of the day,
with generally neutral mid-level heights and stronger flow remaining
confined to the north of the surface cold front. Still, a subtle
mid-level perturbation over eastern KS and the Ozarks late this
morning should continue eastward towards the Mid-South and lower OH
Valley by late afternoon/early evening. This feature, along with
modest low-level convergence along the front, may be sufficient to
encourage initial convective development by 21-23Z across parts of
KY/TN. Even with stronger flow aloft remaining displaced to the
north of the surface warm sector, some veering and gradual
strengthening with height through mid/upper levels should support
sufficient deep-layer shear for updraft organization.

Current expectations are for multiple clusters to develop and pose a
risk for mainly severe/damaging winds as they spread eastward across
the TN and upper OH Valleys through the late afternoon and evening.
With cool temperatures aloft and marginal deep-layer shear to
support supercells, some of this activity could also pose a threat
for isolated hail, especially any cells that can remain at least
semi-discrete. A brief tornado or two also appears possible,
although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow
warm sector expected, convection should generally weaken this
evening as it moves into the higher terrain of the central
Appalachians and encounters a less unstable airmass.

...Mid-South to North Texas...
An elongated mid-level thermal trough, characterized by 500 mb
temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD
observed soundings, extends into much of OK and north TX, well to
the south of the vertically stacked cyclone over Ontario. Low to
mid-level flow should remain modest across this region, with some
signal from various NAM/RAP forecast soundings of a veer-back-veer
signature. Strong speed shear should remain confined above 500 mb,
coincident with poor upper-level lapse rates atop steeper mid-level
lapse rates. This suggests a messy convective mode should be common
as convection increases in the late afternoon and evening, along the
more west/east-oriented portion of the surface cold front. Have
maintained the Marginal Risk for an isolated severe hail/wind threat
with a small westward expansion with this update.

...Oregon...
Isolated to scattered thunderstorms should develop today across
parts of OR as a weak mid-level trough moves northward across the
Pacific Northwest Coast. While low/mid-level flow is expected to
remain rather modest, steepened low-level lapse rates could support
isolated strong/gusty winds with any high-based convection that
develops this afternoon/evening.

..Gleason/Weinman.. 09/05/2025

$$

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ACUS01 KWNS 051954
SWODY1
SPC AC 051952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Fri Sep 05 2025

Valid 052000Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
TENNESSEE VALLEY AND UPPER OHIO VALLEY...

...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two are possible from the Upper Ohio to Tennessee Valleys, mainly
late this afternoon and evening.

...20z Update...
The previous forecast remains on track with no changes required. As
of 1930 UTC, GOES imagery shows meager vertical development of the
cumulus field along and ahead of the cold front across KY and TN.
However, weak surface pressure falls are noted along the frontal
zone, hinting that ascent may be gradually increasing. This trend
should continue as ascent associated with a subtle shortwave trough
over southeast MO continues to spread east, and should aid in
thunderstorm development by late afternoon/early evening. These
observed trends, along with trends in recent CAM guidance, align
with the ongoing forecast.

Across north TX, convective initiation appears more imminent and
should result in increasing severe hail/wind potential through the
evening hours. Based on recent mesoanalysis and forecast soundings,
the convective environment remains adequate for a few strong to
severe thunderstorms. See the previous discussion for additional
details.

..Moore.. 09/05/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Sep 05 2025/

...Ohio Valley/Central Appalachians to the Tennessee Valley...
A large-scale upper trough/low will remain centered over Ontario
today, with mid/upper-level troughing extending southward across
much of the Great Lakes/Midwest into the OH Valley. A cold front
will continue to advance slowly southeastward across portions of the
Mid-South and OH Valley through this evening. Daytime heating of a
seasonably moist low-level airmass ahead of this front over the TN
Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late
afternoon, mainly in KY/TN. Weaker instability is forecast with
northward extent into the upper OH Valley and central Appalachians.

Forcing for ascent aloft will remain nebulous for much of the day,
with generally neutral mid-level heights and stronger flow remaining
confined to the north of the surface cold front. Still, a subtle
mid-level perturbation over eastern KS and the Ozarks late this
morning should continue eastward towards the Mid-South and lower OH
Valley by late afternoon/early evening. This feature, along with
modest low-level convergence along the front, may be sufficient to
encourage initial convective development by 21-23Z across parts of
KY/TN. Even with stronger flow aloft remaining displaced to the
north of the surface warm sector, some veering and gradual
strengthening with height through mid/upper levels should support
sufficient deep-layer shear for updraft organization.

Current expectations are for multiple clusters to develop and pose a
risk for mainly severe/damaging winds as they spread eastward across
the TN and upper OH Valleys through the late afternoon and evening.
With cool temperatures aloft and marginal deep-layer shear to
support supercells, some of this activity could also pose a threat
for isolated hail, especially any cells that can remain at least
semi-discrete. A brief tornado or two also appears possible,
although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow
warm sector expected, convection should generally weaken this
evening as it moves into the higher terrain of the central
Appalachians and encounters a less unstable airmass.

...Mid-South to North Texas...
An elongated mid-level thermal trough, characterized by 500 mb
temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD
observed soundings, extends into much of OK and north TX, well to
the south of the vertically stacked cyclone over Ontario. Low to
mid-level flow should remain modest across this region, with some
signal from various NAM/RAP forecast soundings of a veer-back-veer
signature. Strong speed shear should remain confined above 500 mb,
coincident with poor upper-level lapse rates atop steeper mid-level
lapse rates. This suggests a messy convective mode should be common
as convection increases in the late afternoon and evening, along the
more west/east-oriented portion of the surface cold front. Have
maintained the Marginal Risk for an isolated severe hail/wind threat
with a small westward expansion with this update.

...Oregon...
Isolated to scattered thunderstorms should develop today across
parts of OR as a weak mid-level trough moves northward across the
Pacific Northwest Coast. While low/mid-level flow is expected to
remain rather modest, steepened low-level lapse rates could support
isolated strong/gusty winds with any high-based convection that
develops this afternoon/evening.

$$

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ACUS01 KWNS 060035
SWODY1
SPC AC 060033

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 PM CDT Fri Sep 05 2025

Valid 060100Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
OHIO/TENNESSEE VALLEY REGION...

...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two remains possible across the Upper Ohio/Tennessee Valleys this
evening.

...OH/TN Valley Region...

Latest satellite and radar imagery suggest a low-amplitude
short-wave trough extends across eastern IL into northwestern TN.
Longer radar loops depict the remnants of a long-lived MCV advancing
ahead of this feature across central IN. The southern influence of
the short wave/MCV appears to be encouraging scattered robust
convection along a frontal zone draped across eastern KY into middle
TN. Locally damaging winds have been noted with some of this
activity and wind should remain the primary concern, though
marginally severe hail is also possible, along with some risk for a
brief tornado or two. While deep-layer shear is not particularly
impressive, adequate flow persists along the frontal zone such that
a severe risk will continue through much of the evening.

Farther southwest along the front into north central TX, isolated
severe thunderstorm has developed along the wind shift, just north
of Dallas. Large hail is likely occurring with this storm that has
supercell characteristics at times. 00z sounding from FWD exhibited
very steep lapse rates through 5km, and 0-6km bulk shear was on the
order of 40kt. Given the steep lapse rate environment, some risk for
hail/wind will continue with any storms along the trailing boundary
into this portion of the southern Plains.

..Darrow.. 09/06/2025

$$

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ACUS01 KWNS 060537
SWODY1
SPC AC 060535

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Sat Sep 06 2025

Valid 061200Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MIDDLE
ATLANTIC INTO SOUTHERN NEW ENGLAND...

...SUMMARY...
Scattered strong to severe thunderstorms are possible from eastern
Pennsylvania and New Jersey into parts of southern New England.
Isolated strong gusts are possible extending southward across the
Piedmont.

...Northeastern U.S...

Early-morning water-vapor imagery depicts a well-defined short-wave
trough over eastern IA/southern WI, ejecting east in line with
latest model guidance. This feature will deamplify as it moves
across Lower MI into southern ON by 18z and QC by 07/00z. Following
this lead system, a secondary short-wave trough will eject across
the OH Valley into western PA by early evening. Overall, modest 12hr
height falls are forecast along the international border as 500mb
flow/shear increases across most of the northern Mid Atlantic/New
England. Primary concern for thunderstorm initiation later today
will be a pronounced cold front that will surge across this region
and off the Atlantic Coast by sunrise Sunday. By 18z the wind shift
is expected to extend from upstate NY-eastern PA-western VA. Models
suggest boundary-layer heating will prove instrumental in
destabilization for thunderstorm development along the cold front.
Most CAMs suggest a marked increase in thunderstorms by 18z as
convective temperatures are breached within a favored corridor of
low-level convergence. Forecast soundings exhibit more than adequate
0-6km bulk shear for organized updrafts, and gusty winds will likely
be the primary concern, though some hail could be noted, along with
perhaps a brief tornado or two across the higher latitudes. This
activity will spread toward the Atlantic Coast during the evening
where convection should gradually weaken as it encounters less
buoyancy.

..Darrow/Squitieri.. 09/06/2025

$$

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ACUS01 KWNS 061230
SWODY1
SPC AC 061229

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0729 AM CDT Sat Sep 06 2025

Valid 061300Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID-ATLANTIC REGION INTO NEW ENGLAND...

...SUMMARY...
Scattered severe thunderstorms are possible from eastern
Pennsylvania and New Jersey into New England this afternoon. The
primary hazards will be strong to severe gusts capable of wind
damage and a tornado or two.

...Northeast...
Water-vapor imagery this morning shows a potent mid-level shortwave
trough moving east-northeast across Lower MI and embedded within a
larger scale cyclonic flow field over eastern North America. This
mid-level disturbance will move into southeast Quebec by this
evening. A weak frontal wave is forecast to evolve near the
NY/MA/VT border by early afternoon as a cold front sharpens and
begins to push towards the coast. A relatively moist airmass is
evident in surface observations this morning with dewpoints in the
lower 70s along the southern New England coast with mid to upper 60s
farther inland.

Despite some low cloud cover, sufficient heating will promote
moderate destabilization by early afternoon. Convection will likely
focus along the wind shift/cold front with scattered to numerous
storms eventually developing by mid-late afternoon. Model guidance
shows 35-40 kt southwesterly 700-mb flow and forecast soundings show
hodographs enlarging in the vicinity of the weak low as it migrates north-northeast across portions of southern New England into
southern ME. Several supercells are possible and have introduced
5-percent tornado probabilities this outlook to highlight where the
greatest low-level mesocyclone threat (i.e., possibility for a
tornado or two) is forecast. Otherwise, strong to severe gusts
capable of wind damage are expected from both supercells and the
more organized/intense cores and line segments. As the disturbance
becomes displaced from the region by early evening and with the loss
of heating, the severe risk will likely diminish.

...Mid-Atlantic states into the Carolinas/GA...
Southern extension of stronger flow will gradually taper with south
extent from the Mid-Atlantic states into the Carolinas. However,
sufficient destabilization of a seasonably moist airmass will favor
widely scattered to scattered thunderstorms evolving into a few
bands of thunderstorms this afternoon. The primary risk with the
more intense thunderstorms will be strong to locally severe gusts
capable of wind damage. This activity will likely weaken by the
early evening.

..Smith/Broyles.. 09/06/2025

$$

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ACUS01 KWNS 061604
SWODY1
SPC AC 061603

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1103 AM CDT Sat Sep 06 2025

Valid 061630Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID-ATLANTIC REGION INTO NEW ENGLAND...

...SUMMARY...
Scattered severe thunderstorms are possible from eastern
Pennsylvania and New Jersey into New England this afternoon. The
primary hazards will be strong to severe gusts capable of wind
damage, isolated hail, and a tornado or two.

...The Mid Atlantic Region into New England...
A large upper trough is present today over the Great Lakes region.
At the surface, the effective low-level baroclinic zone extends from
MD into eastern PA/NY and New England. To the east of the boundary,
at least broken sunshine will help to steepen low-level lapse rates
and destabilize the air mass. Thunderstorms have already begun to
form along this zone, with intensification to scattered
strong/severe storms by mid-afternoon. Mid-level lapse rates are
not particularly steep, but southwesterly winds aloft are strong and
deep layer shear will support rotating/bowing structures capable of
damaging wind gusts and some hail. A tornado or two will also be
possible. Model guidance is in agreement that the corridor of
concern is rather narrow, with the main risk between about 19-23z.
Refer to MD #2042 for further details.

..Hart/Weinman.. 09/06/2025

$$

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ACUS01 KWNS 061946
SWODY1
SPC AC 061944

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0244 PM CDT Sat Sep 06 2025

Valid 062000Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID-ATLANTIC REGION INTO NEW ENGLAND...

...SUMMARY...
Scattered severe thunderstorms are possible from eastern
Pennsylvania and New Jersey into New England this afternoon. The
primary hazards will be strong to severe gusts capable of wind
damage, isolated hail, and a tornado or two.

...20z Update...
A severe convective line has evolved across the New England region
earlier than anticipated by most guidance - even recent CAM
solutions - and has a history of producing severe gusts and wind
damage. Across New England ahead of the line, skies are gradually
clearing with temperatures warming into the low 80s. This is
supporting a gradual increase in MLCAPE that should maintain the
squall line as it approaches the coast through early evening. Any
appreciable tornado potential appears highest across this region
based on recent radar trends that depict meridionally-oriented
segments of the line that may support brief circulations. Severe
risk probabilities have been adjusted to reflect these recent
convective trends both ahead of and behind the line. Further to the
southwest, more transient, but at times intense, convection
continues to develop along the cold front from the Mid-Atlantic into
the Southeast. Isolated instances of severe hail/wind will remain
possible through the evening hours as thunderstorms develop within a
buoyant, but modestly sheared environment.

..Moore.. 09/06/2025

.PREV DISCUSSION... /ISSUED 1103 AM CDT Sat Sep 06 2025/

...The Mid Atlantic Region into New England...
A large upper trough is present today over the Great Lakes region.
At the surface, the effective low-level baroclinic zone extends from
MD into eastern PA/NY and New England. To the east of the boundary,
at least broken sunshine will help to steepen low-level lapse rates
and destabilize the air mass. Thunderstorms have already begun to
form along this zone, with intensification to scattered
strong/severe storms by mid-afternoon. Mid-level lapse rates are
not particularly steep, but southwesterly winds aloft are strong and
deep layer shear will support rotating/bowing structures capable of
damaging wind gusts and some hail. A tornado or two will also be
possible. Model guidance is in agreement that the corridor of
concern is rather narrow, with the main risk between about 19-23z.
Refer to MD #2042 for further details.

$$

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ACUS01 KWNS 070027
SWODY1
SPC AC 070025

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0725 PM CDT Sat Sep 06 2025

Valid 070100Z - 071200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not forecast tonight.

...01z Update...

Great Lakes/OH Valley upper trough is progressing steadily east
early this evening. Synoptic cold front is advancing toward the
Atlantic Coast but frontal convection is decidedly weaker as pre
frontal buoyancy is not that great, and now suppressed toward lower
latitudes, well south of stronger deep-layer shear. Thunderstorms
should gradually weaken over the next few hours as boundary layer
continues to cool.

Isolated thunderstorms will also linger across much of the western
U.S. from the southern Rockies, across the Great Basin, into WA/OR.
While a few robust storms may be noted for the next few hours, aside
from locally gusty winds this activity too should weaken with
boundary layer cooling.

..Darrow.. 09/07/2025

$$

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ACUS01 KWNS 070520
SWODY1
SPC AC 070519

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1219 AM CDT Sun Sep 07 2025

Valid 071200Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Some wind and hail risk is expected with thunderstorms across
portions of the central and southern High Plains.

...Central/Southern High Plains...

A few notable disturbances will top the western U.S. ridge and dig
southeast toward the central High Plains later today. Modest
midlevel flow will be noted across this region, and a LLJ is
expected to respond and increase from the TX Panhandle across
western KS during the evening. Latest model guidance depicts strong boundary-layer heating across eastern NM/CO which should allow
surface temperatures to warm into the lower 80s. Forecast soundings
suggest convective temperatures will be breached by 22z and steep
low-level lapse rates will prove beneficial for scattered
thunderstorm development by late afternoon. 0-6km bulk shear is
expected to be on the order of 35kt, so a few organized updrafts may
take on supercell characteristics. If so, isolated hail and gusty
winds are possible. Increasing LLJ after sunset favors this activity
spreading southeast toward western KS and the OK/TX Panhandles.

..Darrow/Squitieri.. 09/07/2025

$$

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ACUS01 KWNS 071210
SWODY1
SPC AC 071209

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0709 AM CDT Sun Sep 07 2025

Valid 071300Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
A few stronger thunderstorms capable of marginally severe wind
gusts/hail are possible across portions of the central and southern
High Plains late this afternoon through the early evening.

...Central/Southern High Plains...
Morning water-vapor imagery shows a low/trough over the eastern
Pacific with a downstream ridge over the Rockies. A couple of weak disturbances are cresting the ridge and may aid in storm development
later this afternoon/evening over the central High Plains later
today.

In the low levels, a lee trough and an associated moisture plume
over the High Plains will provide a focus for isolated to widely
scattered storms. Strong heating over the High Plains will
contribute to weak to moderate buoyancy by late afternoon.
South-southeasterly low-level winds veering to around 20-kt
northwesterly mid-level flow will support some modest updraft
organization. The stronger storms may yield an isolated severe-hail
(diameter 1.5 inches or less) and wind-gust (55-65 mph) threat. A
small cluster or two is expected to evolve during the evening
coincident with an increase in the LLJ. This activity will likely
move east-southeast into western KS and the OK/TX Panhandles, where
a cooling boundary layer and increasing CINH will act to limit
severe potential by mid-late evening.

..Smith/Broyles.. 09/07/2025

$$

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ACUS01 KWNS 071615
SWODY1
SPC AC 071614

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1114 AM CDT Sun Sep 07 2025

Valid 071630Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
A few stronger thunderstorms capable of marginally severe hail/wind
gusts are possible across portions of the central and southern High
Plains late this afternoon and evening.

...Central and Southern High Plains...
An upper ridge axis is present today over the Rockies, with
northwest flow aloft across the high Plains states. A weak
shortwave trough will top the ridge axis over CO and spread into the
central Plains later today. Weak lift and mid-level moisture
associated with this feature will encourage scattered thunderstorm
development by mid-afternoon off the foothills and mountains of
central CO. The activity will propagate southeastward into a moist
and moderately unstable air mass over parts of CO/KS/NM and the
TX/OK Panhandles, where dewpoints in the 50s will yield MLCAPE
values around 2000 J/kg. Winds below 6km are rather weak, which
should limit convective organization. However, steep mid-level
lapse rates and strong winds in the upper levels may result in
isolated supercell structures capable of hail. Morning visible
satellite imagery suggests sufficient cloud cover to limit afternoon
heating somewhat. This may tend to decrease the wind damage threat.

..Hart/Weinman.. 09/07/2025

$$

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ACUS01 KWNS 071934
SWODY1
SPC AC 071932

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0232 PM CDT Sun Sep 07 2025

Valid 072000Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE SOUTHERN TO CENTRAL HIGH PLAINS...

...SUMMARY...
A few stronger thunderstorms capable of marginally severe hail/wind
gusts are possible across portions of the central and southern High
Plains late this afternoon and evening.

...20z Update...
The previous forecast remains on track with no changes required.
Latest convective trends show weak, high-based convection developing
from southern WY into southern CO within the higher terrain.
However, this activity has largely been transient and outflow
dominant. This trend will likely continue until convection can
either migrate into or develop within a low-level moisture plume
extending from the OK/TX Panhandles into eastern CO/western KS where
MLCAPE is more supportive of robust convection. Latest guidance
continues to suggest that the best convective environment will
remain across this region through the evening hours as isolated to
widely scattered convection spreads east. See the previous
discussion for additional details.

..Moore.. 09/07/2025

.PREV DISCUSSION... /ISSUED 1114 AM CDT Sun Sep 07 2025/

...Central and Southern High Plains...
An upper ridge axis is present today over the Rockies, with
northwest flow aloft across the high Plains states. A weak
shortwave trough will top the ridge axis over CO and spread into the
central Plains later today. Weak lift and mid-level moisture
associated with this feature will encourage scattered thunderstorm
development by mid-afternoon off the foothills and mountains of
central CO. The activity will propagate southeastward into a moist
and moderately unstable air mass over parts of CO/KS/NM and the
TX/OK Panhandles, where dewpoints in the 50s will yield MLCAPE
values around 2000 J/kg. Winds below 6km are rather weak, which
should limit convective organization. However, steep mid-level
lapse rates and strong winds in the upper levels may result in
isolated supercell structures capable of hail. Morning visible
satellite imagery suggests sufficient cloud cover to limit afternoon
heating somewhat. This may tend to decrease the wind damage threat.

$$

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ACUS01 KWNS 080030
SWODY1
SPC AC 080028

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 PM CDT Sun Sep 07 2025

Valid 080100Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL/SOUTHERN
HIGH PLAINS...

...SUMMARY...
A few stronger thunderstorms capable of marginally severe hail/wind
gusts remain possible across portions of the central and southern
High Plains, especially this evening.

...01z Update...

Notable short-wave trough has progressed through the western U.S.
ridge and is now digging southeast across eastern WY/CO. Isolated
strong-severe thunderstorms have developed ahead of this feature
within an air mass characterized by 1000-2000 J/kg MLCAPE. 00z
sounding from DDC supports this with around 1000 J/kg MLCAPE, and
0-6km bulk shear on the order of 35kt. Over the next few hours LLJ
is expected to increase across the TX Panhandle into southwestern
NE. This should aid southeast propagation across the central High
Plains, and isolated hail/wind may continue to be observed with the
more robust updrafts. Given the expected increase in LLJ, some of
this activity could linger into the overnight hours.

..Darrow.. 09/08/2025

$$

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ACUS01 KWNS 080540
SWODY1
SPC AC 080539

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Mon Sep 08 2025

Valid 081200Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated hail and damaging gusts are expected over portions of
western Kansas, northwest Oklahoma and the Oklahoma/Texas
Panhandles.

...Central/Southern High Plains...

Mean upper ridge is forecast to hold across the Rockies through the
day1 period, ensuring northwesterly flow persists across the High
Plains. Early this morning, water-vapor imagery depicted a notable
short-wave trough digging southeast across the central High Plains.
This feature is expected to advance into southeast NE/central KS by
late afternoon before advancing into MO/western AR by 09/12z. Partly
in response, LLJ should increase across the High Plains from the TX
Panhandle into south central NE, only veering into eastern KS late
in the period. As a result, low-level warm advection will focus
along a corridor from southern NE into northwest MO, ultimately
inducing one or more thunderstorm clusters along the nose of the
LLJ. Even so, instability may be a bit too weak to warrant much risk
for severe with this activity. Of more concern will be the strongly destabilized regions of western KS into the TX Panhandle, where
low-level lapse rates will steepen due to strong boundary-layer
heating. Forecast soundings suggest convective temperatures will be
breached around 23z, and weak low-level convergence should prove
instrumental in convective initiation, as the aforementioned short
wave will have advanced downstream by this time period. While
large-scale forcing should be weak across this region, most HREF
members develop at least isolated convection. Adequate deep-layer
shear should be present for supercells and these storms will
propagate south with an attendant risk for large hail, locally
damaging winds, and perhaps a brief tornado or two. Greatest severe
risk will be late afternoon into the late evening hours.

...Upper MS Valley Vicinity...

Northern stream short-wave trough is forecast to dig southeast
across southern MB/ND into the upper Red River region by early
evening. This should aid LLJ that will increase across MN into the
U.P. of MI by 09/06z. Large-scale forcing favors elevated convection
along the nose of this jet, especially across the Arrowhead of
MN/Lake Superior. Have introduced a MRGL risk along the trailing
boundary across MN where steeper lapse rates may permit a few robust
updrafts to evolve shortly after peak heating. Even so, this
activity should be more isolated with the greatest concentration of
storms expected within the more favored warm advection zone.

..Darrow/Wendt.. 09/08/2025

$$

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ACUS01 KWNS 081221
SWODY1
SPC AC 081219

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0719 AM CDT Mon Sep 08 2025

Valid 081300Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated large to very large hail and severe gusts are forecast over
portions of southwestern Kansas, northwest Oklahoma, and the Texas
Panhandle late this afternoon into the evening.

...Central/Southern High Plains...
Morning water-vapor imagery shows a mid-level shortwave trough
moving east-southeast across the central High Plains. Scattered showers/thunderstorms are ongoing from northern KS into the
northeast TX Panhandle associated with low-level warm-air advection.
This convection will likely remain weak and slowly shift
east-southeast before largely diminishing 18-21z. As the
aforementioned disturbance moves into central KS by late afternoon,
a differential heating zone arcing northward in wake of the
convection will intersect with a moisture plume extending northward
from west TX into the TX/OK/KS border region.

Heating will contribute to a moderate to very unstable airmass
(2000-3000 J/kg MLCAPE) from the TX Panhandle into southwest KS.
Weak low-level convergence should prove instrumental in convective
initiation late this afternoon into the early evening. Isolated to
scattered thunderstorms are probable with the locally highest risk
for severe in the northeast TX Panhandle into adjacent parts of
northwest OK and southwest KS. Model forecast hodographs are
elongated, which will favor supercells and hail growth given the
magnitude of buoyancy. Large to very large hail (1 to 3 inches in
diameter) is possible with the stronger storms. A brief tornado
cannot be ruled out during the early evening transition when
low-level shear increases. Severe gusts may also accompany the
stronger cores through much of the evening before this activity
diminishes 03-05z.

...Upper MS Valley Vicinity...
Northern stream short-wave trough is forecast to dig southeast
across southern MB/ND into the upper Red River region by early
evening. This should aid in the development and intensification of
a southwesterly LLJ forecast to overspread the Upper Midwest during
the period. Large-scale forcing favors elevated convection along
the nose of this jet, especially across the Arrowhead of MN/Lake
Superior. Relatively steeper lapse rates may permit a few robust
updrafts to evolve shortly after peak heating with an attendant risk
for isolated marginally severe hail.

...Central OR...
A mid- to upper-level shortwave trough located to the west of the
northern CA coast will move east-northeast into southwest OR by late
tonight. Heating coupled with large-scale ascent associated with
the disturbance will favor scattered thunderstorms developing this
afternoon near and east of the Cascades. Forecast soundings show
500-mb temperatures around -15 deg C and weak buoyancy. A couple of
the stronger updrafts may yield a near-severe hail threat (0.50-1.00
inch in diameter) for a few hours.

..Smith/Broyles.. 09/08/2025

$$

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ACUS01 KWNS 081614
SWODY1
SPC AC 081613

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1113 AM CDT Mon Sep 08 2025

Valid 081630Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
SOUTHWEST KANSAS INTO THE EASTERN TEXAS PANHANDLE....

...SUMMARY...
Isolated large hail and gusty winds are forecast over portions of
southwestern Kansas, northwest Oklahoma, and the Texas Panhandle
late this afternoon into the evening.

...TX/OK/KS...
Northwest flow persists over the Plains states today, with a
shortwave trough progressing slowly southeastward across region.
This feature has resulted in overnight and continuing
clouds/convection from northeast KS into the eastern TX panhandle.
These storms have occasionally posed a risk of severe hail. As this
activity drifts eastward this afternoon, strong heating on the
western flank of the clouds, along with a weak residual boundary
over southwest KS/northwest OK, could provide the focus for isolated
supercell thunderstorms. 12z model guidance varies considerably on
the coverage of storms, lending uncertainty to the overall threat.
However, forecast soundings show ample uncapped CAPE and sufficient
low/deep layer shear for rotating storms capable of large hail.
Therefore have made very few changes to the ongoing outlook.

...MN...
Strong heating will occur this afternoon across the eastern Dakotas
and central MN, where a plume of 1000-2000 J/kg of CAPE will
develop. Model guidance continues to decrease in overall coverage
of convection over western MN, and forecast soundings suggest a cap
and weak forcing are contributing to this trend. For these reasons,
have trimmed the southwest portion of the MRGL. A strong storm or
two capable of hail remains possible over central/northeast MN this
evening or tonight.

..Hart/Weinman.. 09/08/2025

$$

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ACUS01 KWNS 081959
SWODY1
SPC AC 081958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Mon Sep 08 2025

Valid 082000Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
SOUTHWEST KANSAS INTO THE EASTERN TEXAS PANHANDLE...

...SUMMARY...
Isolated large hail and gusty winds are forecast over portions of
southwestern Kansas, northwest Oklahoma, and the Texas Panhandle
late this afternoon into the evening.

...20Z Update...
No changes were made to the Day 1 Outlook with this update. Both
timing of the severe risk and storm coverage/evolution remain
uncertain in the southern Plains, given weak/minimal large-scale
forcing and only subtle zones of mesoscale lift. The latest surface
analysis shows a weak surface boundary/wind shift extending from far
southeast CO south-southwestward across the western OK Panhandle
into the far northwestern TX Panhandle. This boundary may move
slowly southeastward this evening and aid in isolated thunderstorm
development as the low-level jet strengthens. Isolated storms could
also form in response to differential heating along the southern
edge of outflow moving southward across southwest KS. Regardless, a
long/mostly straight hodograph (around 40 kt of effective shear) and
moderate surface-based buoyancy will conditionally support splitting
supercells with a risk of large hail and locally severe gusts.

..Weinman.. 09/08/2025

.PREV DISCUSSION... /ISSUED 1113 AM CDT Mon Sep 08 2025/

...TX/OK/KS...
Northwest flow persists over the Plains states today, with a
shortwave trough progressing slowly southeastward across region.
This feature has resulted in overnight and continuing
clouds/convection from northeast KS into the eastern TX panhandle.
These storms have occasionally posed a risk of severe hail. As this
activity drifts eastward this afternoon, strong heating on the
western flank of the clouds, along with a weak residual boundary
over southwest KS/northwest OK, could provide the focus for isolated
supercell thunderstorms. 12z model guidance varies considerably on
the coverage of storms, lending uncertainty to the overall threat.
However, forecast soundings show ample uncapped CAPE and sufficient
low/deep layer shear for rotating storms capable of large hail.
Therefore have made very few changes to the ongoing outlook.

...MN...
Strong heating will occur this afternoon across the eastern Dakotas
and central MN, where a plume of 1000-2000 J/kg of CAPE will
develop. Model guidance continues to decrease in overall coverage
of convection over western MN, and forecast soundings suggest a cap
and weak forcing are contributing to this trend. For these reasons,
have trimmed the southwest portion of the MRGL. A strong storm or
two capable of hail remains possible over central/northeast MN this
evening or tonight.

$$

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ACUS01 KWNS 090039
SWODY1
SPC AC 090037

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0737 PM CDT Mon Sep 08 2025

Valid 090100Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms will spread south across southwestern
Kansas, northwest Oklahoma, and the Texas Panhandle this evening.
Large hail is the primary risk.

...01z Update...

Scattered severe thunderstorms have evolved along the southwestern
flank of a short-wave trough as it digs across eastern KS/northern
OK. The most robust activity is occurring along the eastern fringe
of an instability corridor that extends across the High Plains. 00z
soundings from AMA and DDC support this with 2000-2500 J/kg MLCAPE.
Wind profiles also support organized rotating updrafts and storm
motions favor this convection driving primarily due south,
especially given the orientation of the instability axis. Latest
radar data suggests roughly half a dozen hail-producing updrafts,
primarily located within Severe Thunderstorm Watch #608. Over the
next few hours, LLJ may increase a bit across the TX/OK Panhandle
region, and this also favors southward propagation. Large hail is
the primary concern - some stones may exceed 2 inches.

Farther north, isolated severe thunderstorms have evolved along a
surface boundary draped across northwestern NE into south central
SD. Strong boundary-layer heating proved instrumental in this
development, but nocturnal cooling should lead to weakening over the
next few hours. Until then, a MRGL risk has been added to this
region to account for isolated large hail, primarily through mid
evening.

..Darrow.. 09/09/2025

$$

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ACUS01 KWNS 090525
SWODY1
SPC AC 090524

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 AM CDT Tue Sep 09 2025

Valid 091200Z - 101200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe storms are possible over the central and southern
High Plains late this afternoon and evening.

...Central/Southern High Plains...

Upper ridge, currently located over the Rockies, will gradually
shift into the High Plains during the latter half of the period.
This flow regime will encourage lee troughing across the
central/southern High Plains, and a nocturnal LLJ is also expected
across the TX Panhandle into western KS. In the absence of
meaningful short waves, strong boundary-layer heating will prove
instrumental in convective development as weak height rises are
noted across the Plains. Latest model guidance suggests convective
temperatures will be breached between 21-23z as surface readings
climb through the upper 80s to near 90F from west TX into eastern
CO. While thunderstorms may be delayed over the plains until late
afternoon, scattered convection should readily develop over the
higher terrain by mid afternoon. Some of this activity will spread
toward lower elevations where favorable low-level convergence is
expected to aid at least a few strong-severe thunderstorms. While
deep-layer shear is not forecast to be particularly strong, adequate
flow is expected to support some organization. Even so, storm
coverage should remain isolated and a MRGL Risk will be maintained,
primarily due to storm coverage and negligible large-scale support.
Large hail is the primary concern with this activity.

..Darrow/Wendt.. 09/09/2025

$$

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ACUS01 KWNS 091623
SWODY1
SPC AC 091621

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Tue Sep 09 2025

Valid 091630Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER PARTS OF EASTERN COLORADO AND WESTERN KANSAS...

...SUMMARY...
Widely scattered severe storms are possible over the central and
southern High Plains late this afternoon and evening.

...Central and Southern High Plains...
The upper ridge axis will remain over the Rockies today, with
northwest flow aloft across the Plains states. High-based
thunderstorms are expected to develop off the high terrain of
central CO and northern NM by mid-afternoon, while isolated cells
form over a remnant boundary over eastern CO/western KS. Backed
low-level winds, steep low and mid-level lapse rates, and CAPE
values ranging from 1000-2500 J/kg will promote a risk of a few
severe storms through the afternoon. Large hail appears to be the
main concern, with gusty/damaging winds also possible in the
strongest cells. Activity may persist through much of the evening
as it progresses eastward into an increasingly moist boundary layer
air mass. 12z CAMs show a consistent signal of multiple rounds of
storms affecting parts of eastern CO/western KS, so have added a
small SLGT risk for this region.

..Hart/Weinman.. 09/09/2025

$$

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ACUS01 KWNS 091942
SWODY1
SPC AC 091940

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 PM CDT Tue Sep 09 2025

Valid 092000Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN COLORADO...WESTERN KANSAS...AND THE OKLAHOMA/TEXAS
PANHANDLES...

...SUMMARY...
Widely scattered severe storms are possible over the central and
southern High Plains late this afternoon and evening.

...20z Update - Central/Southern High Plains...

The Slight risk (level 2 of 5) has been expanded southward to
include southwest KS and portions of the OK/TX Panhandles. This
change is based on latest modified RAP/NAM/HRRR/RRFS forecast
soundings, CAMs trends, as well as observation trends.

Temperatures have warmed into the upper 80s to low 90s F across the
region, nearing convective temperatures. Visible satellite imagery
shows cumulus developing in southeast CO within modest low-level
upslope flow, with minor convergence along the theta-e gradient and
surface trough from the northeast TX Panhandle toward the CO/KS
border. Isolated to widely scattered thunderstorms are expected to
develop by late afternoon and spread east/southeast into this
evening.

Vertically veering wind profiles, with forecast hodographs becoming elongated/straight above 1-2 km, will support supercells. Steep low
and midlevel lapse rates and 1000-2500 J/kg MLCAPE values amid
favorable shear will favor large hail, with some potential for
stones greater than 2 inch diameter possible. Strong gusts may also
accompany stronger convection.

..Leitman.. 09/09/2025

.PREV DISCUSSION... /ISSUED 1121 AM CDT Tue Sep 09 2025/

...Central and Southern High Plains...
The upper ridge axis will remain over the Rockies today, with
northwest flow aloft across the Plains states. High-based
thunderstorms are expected to develop off the high terrain of
central CO and northern NM by mid-afternoon, while isolated cells
form over a remnant boundary over eastern CO/western KS. Backed
low-level winds, steep low and mid-level lapse rates, and CAPE
values ranging from 1000-2500 J/kg will promote a risk of a few
severe storms through the afternoon. Large hail appears to be the
main concern, with gusty/damaging winds also possible in the
strongest cells. Activity may persist through much of the evening
as it progresses eastward into an increasingly moist boundary layer
air mass. 12z CAMs show a consistent signal of multiple rounds of
storms affecting parts of eastern CO/western KS, so have added a
small SLGT risk for this region.

$$

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ACUS01 KWNS 100100
SWODY1
SPC AC 100059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Tue Sep 09 2025

Valid 100100Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL
HIGH PLAINS...

...SUMMARY...
Widely scattered severe storms remain possible over the central and
southern High Plains this evening.

...Central High Plains...
Widely scattered strong to severe storms persist this evening from
far eastern CO and western KS into the TX Panhandle. The most likely
area for continued severe storms producing hail and strong gusts
appears to be over western KS, beneath the cooler temperatures
aloft, and currently within instability axis. Increasing winds
around 850 mb may further support storms through the evening with southeastward-moving cells.

For more information see mesoscale discussion 2056.

..Jewell.. 09/10/2025

$$

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ACUS01 KWNS 100504
SWODY1
SPC AC 100502

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1202 AM CDT Wed Sep 10 2025

Valid 101200Z - 111200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered showers and thunderstorms are possible over parts of the
Northwest and northern Rockies with more isolated storms over the
High Plains. Severe potential is generally low.

...Synopsis and Discussion...
An upper low will remain nearly stationary over the western states
with a large area of cyclonic flow aloft from southern CA into the
eastern Great Basin and central Rockies. Meanwhile, another broad
but weaker upper trough will affect the eastern states with cool air
aloft extending from the MS Valley into the Northeast. Between these
two troughs, an upper ridge will exist over the Plains, with upper
high over western TX.

At the surface, high pressure will extend southward across the Great
Lakes and into much of the East, resulting in stable conditions.
Weak southerly winds across the Plains will maintain pockets of 50s
and low 60s F dewpoints, with greater moisture along the TX Coast.

Early day storms are likely to be ongoing over KS into northern OK,
but are expected to dwindle during the day. A few strong wind gusts
cannot be ruled out prior to this activity weakening. Otherwise, a
few isolated cells may occur from northeast NM into eastern WY
during the late afternoon with heating and weak upslope flow.
Warming aloft is expected to mitigate overall potential.

Elsewhere, scattered afternoon storms will occur beneath the upper
trough from northern NV into OR and western ID, and a few of these
storms could produce at least small hail given such cool
temperatures aloft and modest deep-layer shear.

..Jewell/Wendt.. 09/10/2025

$$

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ACUS01 KWNS 101247
SWODY1
SPC AC 101245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Wed Sep 10 2025

Valid 101300Z - 111200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered showers and thunderstorms are possible over parts of the
Northwest and northern Rockies with more isolated storms over the
High Plains. Severe potential is generally low.

...Synopsis...
Water-vapor imagery this morning shows an upper low situated over
northern CA, and it will remain nearly stationary during the period
with a large area of cyclonic flow extending from southern CA into
the eastern Great Basin and central Rockies. A downstream upper
ridge over the High Plains will feature a lee trough that will act
to focus isolated to scattered thunderstorms from MT southward into
the central High Plains.

Strong heating and weak upslope flow beneath the aforementioned
upper-level ridge will favor a few isolated cells developing during
peak heating. A couple of the more vigorous storms may be capable
of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the
CO Front Range in the High Plains, and 3) in eastern WY. Warming
aloft is expected to mitigate the overall potential with these
storms. Farther west, a mid-level shortwave trough will move
through the base of the West Coast mid- to upper low/trough and to
near the UT/NV border by late afternoon/early evening. A
corresponding belt of 50-kt southwesterly 500-mb flow will
overspread western UT. Isolated dry microbursts may accompany the
stronger storms over central UT into western CO during the 22-02z
period.

Elsewhere, scattered afternoon storms will occur beneath the upper
trough from northern NV into OR and western ID, and a few of these
storms could produce at least small hail given such cool
temperatures aloft and modest deep-layer shear.

..Smith/Broyles.. 09/10/2025

$$

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ACUS01 KWNS 101632
SWODY1
SPC AC 101630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Wed Sep 10 2025

Valid 101630Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR
WEST...

...SUMMARY...
A few severe storms could occur this afternoon and early evening
across the north-central High Plains and Great Basin.

...High Plains/Front Range...
As the upper ridge tends to abate/shift away, the region will begin
to be influenced by the upper trough over the West. While some
stronger storms could occur across a relatively broad north-south
extent of the High Plains, portions of eastern Wyoming and the
northern Colorado Front Range and immediately adjacent High Plains
are expected to be influenced by somewhat stronger mid-level
westerlies (25 kt), aside from steep lapse rates and moderate
buoyancy. Low severe probabilities have been introduced for what
should be an isolated/relatively marginal severe potential later
this afternoon into evening.

...Great Basin/Interior West...
The region will be influenced by a belt of stronger cyclonic flow
aloft preceding the upper low centered over northern California.
Adequate moisture, steep lapse rates, and stronger deep-layer winds
could allow for some storms to produce gusty winds and small hail,
mainly across central/northern Nevada into southwest Idaho.

..Guyer/Weinman.. 09/10/2025

$$

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ACUS01 KWNS 101930
SWODY1
SPC AC 101929

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Wed Sep 10 2025

Valid 102000Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR
WEST...

...SUMMARY...
A few severe storms could occur this afternoon and early evening
across the north-central High Plains and Great Basin.

...20z Update...
No changes are needed to the D1 Convective Outlook. See previous
discussion below for more information.

..Thornton.. 09/10/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Sep 10 2025/

...High Plains/Front Range...
As the upper ridge tends to abate/shift away, the region will begin
to be influenced by the upper trough over the West. While some
stronger storms could occur across a relatively broad north-south
extent of the High Plains, portions of eastern Wyoming and the
northern Colorado Front Range and immediately adjacent High Plains
are expected to be influenced by somewhat stronger mid-level
westerlies (25 kt), aside from steep lapse rates and moderate
buoyancy. Low severe probabilities have been introduced for what
should be an isolated/relatively marginal severe potential later
this afternoon into evening.

...Great Basin/Interior West...
The region will be influenced by a belt of stronger cyclonic flow
aloft preceding the upper low centered over northern California.
Adequate moisture, steep lapse rates, and stronger deep-layer winds
could allow for some storms to produce gusty winds and small hail,
mainly across central/northern Nevada into southwest Idaho.

$$

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ACUS01 KWNS 110102
SWODY1
SPC AC 110100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Wed Sep 10 2025

Valid 110100Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER FAR WESTERN
NEBRASKA INTO A SMALL PART OF NORTHEAST COLORADO...

...SUMMARY...
Isolated severe storms remain possible over far western Nebraska and
perhaps extreme northeastern Colorado early this evening. A few
storms storms will also affect parts of western Idaho into eastern
Oregon during the early evening.

...Discussion...
A small cluster of severe storms likely producing hail is currently
affecting far western NE. These storms are within a small area of
uncapped air mass, and will likely remain tied to the immediate area
and perhaps affect a small portion of northeast CO before
diminishing. Strong southeast surface winds/inflow will likely
support the ongoing cluster for a couple hours before CIN becomes
too large. For more information, see mesoscale discussion 2059.

Elsewhere, a band of thunderstorms continues to move northward
across southwest ID and southeast OR ahead of the upper vorticity
max. The 00Z BOI sounding shows steep midlevel lapse rates and
marginal overall shear, and this may support gusty winds or small
hail. However, the overall risk for severe storms appears low after
sunset with limited instability.

..Jewell.. 09/11/2025

$$

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ACUS01 KWNS 110557
SWODY1
SPC AC 110555

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Thu Sep 11 2025

Valid 111200Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
MONTANA INTO WESTERN NORTH DAKOTA...

...SUMMARY...
A corridor of strong to severe thunderstorms with hail and damaging
gusts are expected from eastern Montana into western North Dakota,
while isolated/localized wind or marginal hail will be possible
across a large portion of the Rockies.

...Synopsis...
A large, positive-tilt upper trough will remain nearly stationary
across the western CONUS, with axis extending from western NV into
southern MB/SK. East of this trough, a broad fetch of 30-40 kt 500
mb southwesterlies will affect much of the Rockies and disturbances
rounding the upper ridge into the northern Plains.

At the surface, high pressure will maintain stable conditions over
much of the East, where a elongated/weak upper trough will exist.
Southerly surface winds will maintain a low-level moist plume across
the MO Valley with 60s F dewpoints, with 50s F into much of eastern
MT where surface winds will back to southeasterly.

The combination of daytime heating and substantial southwest flow
aloft across a large part of the Rockies, along with at least
marginal instability over a wide area suggest sporadic strong to
severe storms will be possible during the afternoon and evening.

...Rockies into the northern Plains...
Lapse rates will steepen over the area as heating commences, and
with the 500 mb -10 C isotherm extending from SD to southern UT. By
virtue of an uncapped air mass, sporadic afternoon storms are likely
over the higher terrain over northwest NM, CO, and over much of ID
into MT, while warm and drier air will generally be found from UT
into parts of central WY. However, even in the drier areas, a few
storms are likely as weak levels of instability develop.
Conditionally, the entire region will have deep-layer shear at or
above 35-40 kt, which will favor cellular storm mode. Small hail
appears most likely over much of the Intermountain West, with
locally strong gusts as well.

A potentially greater severe threat will extend from eastern MT and
WY into the western Dakotas, where moisture and instability will be
greater. A surface low is expected over southeast MT/northwest SD,
with backed/moist winds wrapping west. Forecast soundings in this
area depict robust CAPE profiles and hodographs favoring cells
producing hail, or perhaps bowing structures with both wind and hail
risk. Storms may form over south-central MT/northern WY after 21Z,
moving into the western Dakotas during the evening.

..Jewell/Wendt.. 09/11/2025

$$

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