• MESO: Mesoscale Discussion 1888

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Oct 24 17:41:32 2021
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    ACUS11 KWNS 241741
    SPC MCD 241740=20

    Mesoscale Discussion 1888
    NWS Storm Prediction Center Norman OK
    1240 PM CDT Sun Oct 24 2021

    Areas affected...Much of MO and parts of west-central IL

    Concerning...Severe potential...Tornado Watch likely=20

    Valid 241740Z - 242015Z

    Probability of Watch Issuance...95 percent

    SUMMARY...The threat for tornadoes, large hail, and severe wind
    gusts will increase as storms develop and intensify this afternoon.
    Tornado Watch issuance will be needed.

    DISCUSSION...A low-amplitude shortwave trough will continue moving
    eastward across the central Plains and MO Valley this afternoon.
    Large-scale ascent preceding this feature is already supporting
    isolated convection ahead of a cold front just east of the KS/MO
    border. Latest surface observations show a warm front extends
    eastward across MO. With a surface low progged to develop across
    northern MO this afternoon, this warm front may lift northward a
    little bit more across MO over the next few hours. Diurnal heating
    of a moist low-level airmass across this region along with steep
    mid-level lapse rates will likely support 1500-2000 J/kg of MLCAPE
    by mid to late afternoon. A veering and strengthening wind profile
    at both low and mid levels will foster 40-50 kt of effective bulk
    shear, which is more than sufficient for supercells.

    Current expectations are for surface-based storms to develop along
    or just ahead of the cold front across western MO by 19-20Z (2-3 PM
    CDT). Some short-term guidance suggests that other storms may
    initiate across the open warm sector as well. Supercells will likely
    be the dominant storm mode initially this afternoon, as sufficient cross-boundary flow aloft is present along and ahead of the cold
    front. Given the steep mid-level lapse rates present, large hail
    should occur with these supercells. Low-level shear also appears
    strong in recent VWPs from KEAX/KSGF. Effective SRH in the 200-300
    m2/s2 range will likely foster low-level rotation and potential for
    tornadoes with any supercells. The best low-level shear and related
    tornado potential may exist along the warm front, where low-level
    winds will be backed to a more east-southeasterly direction. A
    couple of these tornadoes, especially across MO, could be strong
    since the thermodynamic and kinematic environment both appear rather
    favorable. With time, one or more broken lines of supercells and/or
    small clusters are expected to advance eastward across MO and into
    parts of west-central IL. The severe wind threat may eventually
    increase, especially if storms develop more linear characteristics
    versus a broken line of supercells. Regardless of eventual
    convective evolution, the increasing severe threat this afternoon
    will require Tornado Watch issuance within the next couple of hours
    (likely by 2-3 PM CDT).

    ..Gleason/Thompson.. 10/24/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!pM_Xro2Q4h-zC_RpWXdDIEjASJz4a3hPI53HHoBsrkBjn9Ze50YJT9NJL4lOstptUHqz5qJN$=
    for graphic product...


    LAT...LON 39649093 39289040 38789001 37719066 36919151 36519239
    36519370 36559457 37019458 37639452 38939409 39839351
    39869273 39819162 39649093=20

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