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  • MESO: Mesoscale Discussion 0571

    From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Mon Apr 27 18:45:12 2026
    ACUS11 KWNS 271845
    SWOMCD
    SPC MCD 271844=20
    KYZ000-TNZ000-INZ000-ILZ000-MOZ000-ARZ000-272045-

    Mesoscale Discussion 0571
    NWS Storm Prediction Center Norman OK
    0144 PM CDT Mon Apr 27 2026

    Areas affected...Southern IL...southeast MO...western KY...western
    TN...and northeast AR

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

    Valid 271844Z - 272045Z

    Probability of Watch Issuance...95 percent

    SUMMARY...The supercell tornado risk will increase through the
    afternoon into this evening. A few strong-intense tornadoes will be
    possible. A Tornado Watch is likely.

    DISCUSSION...Visible satellite imagery shows increasingly agitated boundary-layer cumulus evolving in the open warm sector near the
    confluence of the OH/MS Rivers and southward. Here, diurnal heating
    of a moist air mass (upper 60s to lower 70s dewpoints) beneath steep
    midlevel lapse rates (around 8.5 C/km per SGF 18Z sounding) is
    yielding strong surface-based buoyancy. Over the next several hours, discrete/semi-discrete thunderstorms should develop within areas of differential heating and north/south-oriented confluence zones,
    aided by an increasing low-level mass response accompanying a
    deepening surface cyclone to the north. The strong buoyancy and
    around 50 kt of effective shear will favor supercells, and modest
    large-scale forcing for ascent and some lingering capping at the
    base of the EML should favor a discrete/semi-discrete mode. Given a
    50 kt southerly low-level jet and associated large clockwise-curved
    hodographs (250-300+ m2/s2 effective SRH) -- strongest with
    northward extent, several supercell tornadoes and very large
    hail/damaging winds are expected. The best overlap of strongest
    low-level shear and buoyancy is expected over southern IL, southeast
    MO, and western KY, where a few strong-intense tornadoes are
    possible.=20

    A Tornado Watch issuance is likely.

    ..Weinman/Guyer.. 04/27/2026

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!5e1r_kJczXqAmFUelAWFP6dCMHsa5KVku_to5LMJTZeUfUDBpgdxJLIo7vhLJP_XR1xdCVhDj= vjtr-Ap9zbFreDhKlo$ for graphic product...

    ATTN...WFO...OHX...PAH...MEG...LSX...LZK...SGF...

    LAT...LON 37029096 37529027 37778971 37908922 37988848 37938773
    37668737 37288722 36918728 36618745 36218761 35748784
    35398820 35178865 35078922 35048991 35039057 35129110
    35479158 35979157 36519131 37029096=20

    MOST PROBABLE PEAK TORNADO INTENSITY...140-170 MPH
    MOST PROBABLE PEAK WIND GUST...55-70 MPH
    MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


    =3D =3D =3D
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