• MESO: Mesoscale Discussion 1773

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Sep 21 16:52:37 2021
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    ACUS11 KWNS 211652
    SPC MCD 211651=20

    Mesoscale Discussion 1773
    NWS Storm Prediction Center Norman OK
    1151 AM CDT Tue Sep 21 2021

    Areas affected...portions of central and southern Arkansas into
    western Mississippi

    Concerning...Severe potential...Watch unlikely=20

    Valid 211651Z - 211915Z

    Probability of Watch Issuance...20 percent

    SUMMARY...A couple damaging gusts may accompany the stronger storms.
    A WW issuance is not expected given the anticipated isolated, brief
    nature of the severe threat.

    DISCUSSION...Thunderstorms have been increasing in number and
    intensity along the cold front given low-level convergence and ample
    diurnal heating. Surface temperatures in the mid to upper 80s F,
    coupled with mid to upper 70s F dewpoints, are currently
    contributing to 1000-2000 J/kg MLCAPE despite the relative absence
    of appreciable lapse rates. However, as diurnal heating promotes
    further heating and boundary-layer mixing, low-level lapse rates
    should steadily improve through the afternoon, with further
    increases in MLCAPE expected.=20

    A few ongoing storms have already shown up to 35 dBZ cores exceeding
    60 kft, and with increasing instability, a greater number of deeper water-loaded cores are expected. Despite the overall lack of robust
    upper support and vertical wind shear ahead of the front,
    water-loaded cores may support a couple of damaging gusts through
    the afternoon. Nonetheless, given poor shear and brief,
    pulse-cellular storm modes, the severe threat is expected to remain
    sparse and brief, and a WW issuance appears unlikely.

    ..Squitieri/Hart.. 09/21/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!s5BNZVLBflJ3eDg7zTnH7aa86bLQOW0mLXTIgW0c1bgLNvi6IlSIJedOyqA-njXkbAy4tQzt$=
    for graphic product...


    LAT...LON 33219453 34329332 34929224 35129125 35069027 34808974
    34208943 33858941 33218970 32849017 32669086 32669196
    32839375 33219453=20

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