• MESO: Mesoscale Discussion 0496

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon May 3 19:09:30 2021
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    ACUS11 KWNS 031909
    SPC MCD 031908=20

    Mesoscale Discussion 0496
    NWS Storm Prediction Center Norman OK
    0208 PM CDT Mon May 03 2021

    Areas affected...Eastern Missouri into central Illinois

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

    Valid 031908Z - 032015Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Thunderstorms will likely overspread eastern Missouri into
    central and northern Illinois over the next several hours. Scattered
    strong to severe storms are likely and will support a risk for
    damaging wind and hail.

    DISCUSSION...Recent visible satellite imagery reveals gradually
    clearing skies across western and southern IL ahead of a cold front
    draped from central WI southward through western MO. This is also
    just ahead of a remnant MCV that is slowly propagating eastward
    ahead of the front. Recent RAP mesoanalysis indicates MLCIN is
    decreasing across the clearing warm sector where temperatures are
    warming into the low 70s/upper 80s and deeper boundary-layer mixing
    is eroding remaining inhibition. Insolation, combined with low to
    mid 60s dewpoints and mid-level lapse rates approaching 7 C/km, is
    supporting MLCAPE values on the order of 1000-1500 J/kg. While the
    most favorable air mass is currently limited to eastern MO/western
    IL, the warm sector should spread eastward with time as clearing

    30-45 knots of effective bulk shear nearly orthogonal to the front
    and a subtle surface trough extending southward from the MCV (noted
    in surface obs across central MO) should support semi-discrete cells
    within a broken line along the front. Low-level shear is expected to
    gradually increase across the warm sector with ESRH values near 150
    m2/s2, which may support a tornado threat - particularly in the
    vicinity of the MCV across central IL where low-level flow may be
    slightly more backed to the southeast (though confidence in this
    potential is low). Regardless, a watch is likely in the coming hours
    as convection continues to develop.

    ..Moore/Grams.. 05/03/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!s3o3AvVB6n4wRuoPM2Fbc2ZXkw_l85b7PyxVcdSCUd1j6SIz2kaJzodC75m-H4DJZ7xuO_eO$=
    for graphic product...


    LAT...LON 38819228 39879213 40729208 41339111 41458985 41148864
    40428791 39678769 38848792 38268844 38018929 38009046
    38079177 38819228=20

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