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  • MESO: Mesoscale Discussion 1374

    From COD Weather Processor@1:2320/127 to wx-storm@lists.illinois.edu on Mon Jun 29 08:03:22 2026
    ACUS11 KWNS 290803
    SWOMCD
    SPC MCD 290802=20
    SDZ000-NEZ000-291000-

    Mesoscale Discussion 1374
    NWS Storm Prediction Center Norman OK
    0302 AM CDT Mon Jun 29 2026

    Areas affected...much of central South Dakota

    Concerning...Severe Thunderstorm Watch 412...

    Valid 290802Z - 291000Z

    The severe weather threat for Severe Thunderstorm Watch 412
    continues.

    SUMMARY...Storms over south-central South Dakota are expected to
    become an intense complex over the next couple hours, producing
    winds of 75-90 mph and large hail across central parts of the state.

    DISCUSSION...Earlier supercells have merged near the cold front and
    surface low over southwest SD, with recent radar trends indicating
    the early stages of upscale growth into a compact but significantly
    severe MCS. Aside from the supercell over Bennett County SD, radar
    also shows a warm advection wing developing east/northeast of it,
    with additional development south of this cell along the cold front.
    This evolution is taking place near a substantial 850 mb theta-e
    gradient, with MUCAPE up to 4000 J/kg along and south of the surge.

    Given recent trends, strong instability and steep lapse rates aloft,
    and a favorable low-level jet, confidence is increasing that this
    complex will strengthen, and possible accelerate northeastward
    through the morning hours. Additional watches may be required
    downstream into more of northern/northeast SD and southeast ND as
    the scenario evolves.

    ..Jewell.. 06/29/2026

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_ehkto48nU9c6WSou1avjEGsvgxH79Iva95Z9j-T9FHdecVZwdm9WdNZKu8pkw320mK0iYXCv= YM7kAoVArppG5U8WcA$ for graphic product...

    ATTN...WFO...FSD...ABR...LBF...UNR...

    LAT...LON 42900231 43320213 43610187 44000134 44560086 45220005
    45179925 44989881 44579880 43819925 43180022 42920144
    42760224 42900231=20

    MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
    MOST PROBABLE PEAK WIND GUST...75-90 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


    =3D =3D =3D
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    * Origin: Capitol City Weather Station (1:2320/127)