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  • MESO: Mesoscale Discussion 1999

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Aug 21 22:21:40 2025
    ACUS11 KWNS 212221
    SWOMCD
    SPC MCD 212221=20
    MNZ000-SDZ000-NDZ000-212345-

    Mesoscale Discussion 1999
    NWS Storm Prediction Center Norman OK
    0521 PM CDT Thu Aug 21 2025

    Areas affected...Parts of west-central MN...far southeastern
    ND...and eastern/central SD

    Concerning...Severe potential...Watch possible=20

    Valid 212221Z - 212345Z

    Probability of Watch Issuance...40 percent

    SUMMARY...Monitoring the area for some increase in
    severe-thunderstorm potential over the next few hours. Any sustained
    storms will be capable of producing large hail and severe gusts. It
    is unclear if a watch is needed.

    DISCUSSION...Latest surface observations show a pre-frontal wind
    shift extending from far southeastern ND into eastern/central SD.
    Isolated thunderstorms have developed along the wind shift in far
    southeastern ND, while a separate area of boundary-layer cumulus has
    attempted to deepen over east-central SD. Along/ahead of the surface
    boundary, strong diurnal heating amid middle 70s dewpoints and steep
    midlevel lapse rates has eroded antecedent convective inhibition and
    is contributing to a strongly unstable air mass. At the same time,
    the ABR VWP is sampling around 40 kt of 0-6 km shear, which is
    oriented oblique to the surface boundary. While generally weak
    large-scale forcing for ascent and some lingering inhibition cast
    uncertainty on storm coverage and longevity, any storms that do
    evolve could become discrete/semi-discrete supercells and pose a
    risk of large hail and locally severe wind gusts. Given the
    uncertainty in storm coverage/longevity, it is unclear if a watch
    will be needed, though convective trends are being monitored.

    ..Weinman/Mosier.. 08/21/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!83GVUpyUUcMXL_ACLCU_-6wv-v-Sio1xOgAv7q-T0_3QQq79357UHAIvb8fhvwl8cnB0OkbeF= V4WzJrPd2SH3WrAqeU$ for graphic product...

    ATTN...WFO...MPX...FGF...FSD...ABR...

    LAT...LON 46899512 46409501 45769528 45139602 44659674 43919833
    43759901 43919947 44189970 44709965 45099893 46139719
    46909649 47179601 47179555 46899512=20

    MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
    MOST PROBABLE PEAK WIND GUST...55-70 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


    =3D =3D =3D
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