• MESO: Mesoscale Discussion 1621

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Jul 9 23:31:10 2025
    ACUS11 KWNS 092331
    SWOMCD
    SPC MCD 092330=20
    SDZ000-NDZ000-NEZ000-100100-

    Mesoscale Discussion 1621
    NWS Storm Prediction Center Norman OK
    0630 PM CDT Wed Jul 09 2025

    Areas affected...South-central ND...central SD...and north-central
    NE

    Concerning...Severe Thunderstorm Watch 498...

    Valid 092330Z - 100100Z

    The severe weather threat for Severe Thunderstorm Watch 498
    continues.

    SUMMARY...Isolated/sporadic large hail and embedded severe wind
    gusts remain possible across Severe Thunderstorm Watch 498. While
    uncertain, there is some potential for eventual upscale growth into
    one or more clusters into tonight.

    DISCUSSION...Two disorganized clusters with transient/embedded
    deeper cores are drifting slowly east-southeastward across the
    Dakotas and northern NE this evening -- where periodic severe wind
    gusts and large hail are occurring. Weak large-scale forcing for
    ascent and strong buoyancy/steep deep-layer lapse rates have
    generally promoted outflow dominant storms with limited large-scale organization up to this point. Nevertheless, the strong buoyancy and long/generally straight hodographs (around 40 kt of effective shear)
    will continue to promote severe downbursts/outflow and sporadic
    large hail with the stronger embedded cores.=20

    While the weak forcing for ascent casts uncertainty on overall
    convective evolution, a gradually strengthening low-level jet may
    promote eventual upscale growth into one or more organized clusters
    into tonight. Confidence in this scenario is relatively higher for
    the southern area of storms currently over southern SD into northern
    NE -- as the low-level jet may tend to focus over this general
    region amid slightly stronger deep-layer shear. If this evolution
    can occur, the risk of severe wind gusts would increase with time,
    and a downstream watch would eventually be needed.

    ..Weinman.. 07/09/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7kma3WtjFLnB-CR7zk9kqiaaag_PfFWoA3iD6ISPiJL3zeY-uxnAWFrgDjOfqKSHXsethb6h_= XDuuMMZreOZJmzmyv0$ for graphic product...

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

    LAT...LON 46990014 46129975 45229956 44219951 43219932 41729957
    41330009 41310092 41320168 41740205 43040179 44910166
    46500184 47180102 47180049 46990014=20

    MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
    MOST PROBABLE PEAK WIND GUST...65-80 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


    =3D =3D =3D
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