• DAY1SVR: Day 1 Convective Outlook Corr 1

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, August 24, 2025 13:11:57
    ACUS01 KWNS 241311
    SWODY1
    SPC AC 241310

    Day 1 Convective Outlook CORR 1
    NWS Storm Prediction Center Norman OK
    0810 AM CDT Sun Aug 24 2025

    Valid 241300Z - 251200Z

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

    CORRECTED FOR GRAPHICS

    ...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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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, September 11, 2025 17:12:16
    ACUS01 KWNS 111712
    SWODY1
    SPC AC 111710

    Day 1 Convective Outlook CORR 1
    NWS Storm Prediction Center Norman OK
    1210 PM CDT Thu Sep 11 2025

    Valid 111630Z - 121200Z

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

    CORRECTED FOR PROB GRAPHICS

    ...SUMMARY...
    Scattered severe thunderstorms are expected over eastern Montana
    into western North Dakota late this afternoon through the evening.
    The primary hazards are severe wind gusts and large hail.

    ...Synopsis...
    Water-vapor imagery shows a large cyclone over the West with a
    downstream ridge over the Great Plains, and a trough centered over
    the Lower Great Lakes. Southwesterly mid to high-level flow extends
    from the base of the larger-scale western U.S. trough northeastward
    through the Great Basin and into the northern Great Plains. A
    mid-level disturbance implied in water-vapor imagery over western
    WY, is forecast to move northeast into eastern MT/western ND towards
    this evening.

    In the low levels, a plume of seasonably rich moisture will protrude
    northward from the central Plains into the Dakotas and eastern MT.
    A lee trough will extend southward from a surface low over the
    northern High Plains.

    ...Rockies into the northern Plains...
    An ongoing cluster of thunderstorms associated with warm-air
    advection near the ND/Manitoba border will continue to move
    east-northeastward into southern Canada ahead of a pair of MCVs over
    western ND/eastern MT. Diurnal heating over the higher terrain from
    near the Four Corners northward into southern MT will favor
    scattered thunderstorms developing during the midday into the early
    afternoon. Storm coverage will increase further over the central
    Rockies during the afternoon, with the stronger storms capable of an
    isolated hail/wind threat. As the airmass destabilizes over the
    plains, particularly across eastern MT within the moist plume
    primarily north of the surface low, isolated to scattered storms are
    forecast by mid to late afternoon. This initial activity will
    probably develop near the MT/WY border with upscale growth into a
    cluster possible during the evening. Deep-layer shear supporting
    organized storm modes coupled with steep lapse rates, will combine
    to aid in several stronger storms capable of a hail/wind threat.
    The wind threat will probably continue into ND during the evening
    within the terminus region of a 35-40 kt southerly LLJ. A gradual
    transition to increasingly elevated convection is expected late as
    convective inhibition increases and the overall severe risk lessens.

    ..15_ows.. 09/11/2025

    $$

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