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  • MESO: Mesoscale Discussion 1971

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Aug 17 07:48:23 2025
    ACUS11 KWNS 170748
    SWOMCD
    SPC MCD 170747=20
    SDZ000-NDZ000-170915-

    Mesoscale Discussion 1971
    NWS Storm Prediction Center Norman OK
    0247 AM CDT Sun Aug 17 2025

    Areas affected...Northwest/north-central SD into
    southwest/south-central ND

    Concerning...Severe Thunderstorm Watch 597...

    Valid 170747Z - 170915Z

    The severe weather threat for Severe Thunderstorm Watch 597
    continues.

    SUMMARY...An increase in the severe-wind threat remains possible
    overnight.

    DISCUSSION...A storm cluster over western SD has shown signs of
    becoming better organized over the last 30-60 minutes, with
    indications of bow-echo development across northwest SD, and recent
    observed wind gusts of 50-60 mph. MUCAPE remains in the 2500-4000
    J/kg range, due to steep midlevel lapse rates atop a richly moist
    boundary layer (as observed in the 00Z UNR sounding). Meanwhile,
    backed low-level flow beneath modest southwesterlies aloft is
    supporting effective shear of 25-35 kt, sufficient for organized
    convection.=20

    A modest nocturnal low-level jet combined with the favorable
    instability and deep-layer shear will support continued
    intensification of the ongoing cluster, and maintenance of this
    cluster through much of the overnight hours. Short-term guidance
    suggests that this developing MCS will generally move northeastward
    along the MUCAPE and low-level moisture gradient. The magnitude of
    the wind threat remains somewhat uncertain, due to the presence of
    low-level stability and surface-based CINH. However, if an organized
    MCS does persist, some increase in severe-wind potential is expected
    overnight from northern SD into southern ND.

    ..Dean.. 08/17/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_rYcV0fFATylJzsY0UOdskVCCwkZcGQ2Qlkq6bDVvFW7Z7TadAm9abE_4FdqJpolN3C9bPEhz= lFg9HwrDcNGnSLEq8E$ for graphic product...

    ATTN...WFO...ABR...BIS...UNR...

    LAT...LON 45690234 46320209 46540110 46709979 45869933 45339923
    44759944 44280019 44370204 45240186 45690234=20

    MOST PROBABLE PEAK WIND GUST...65-80 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


    =3D =3D =3D
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