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  • MESO: Mesoscale Discussion 0400

    From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Mon Apr 13 19:43:18 2026
    ACUS11 KWNS 131943
    SWOMCD
    SPC MCD 131942=20
    IAZ000-MNZ000-SDZ000-NEZ000-132115-

    Mesoscale Discussion 0400
    NWS Storm Prediction Center Norman OK
    0242 PM CDT Mon Apr 13 2026

    Areas affected...portions of northeastern Nebraska into far
    southeastern South Dakota...extreme southwestern Minnesota...and
    extreme northwestern Iowa

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

    Valid 131942Z - 132115Z

    Probability of Watch Issuance...60 percent

    SUMMARY...The severe threat should generally increase north of a
    surface low over portions of northern NE into far southeastern SD
    over the next few hours. Convective trends are being monitored for
    the need of a WW issuance.

    DISCUSSION...Low 60s F surface dewpoints are pivoting around and to
    the north of a surface low over central NE, which is boosting MLCAPE
    over 2000 J/kg given 8-9 C/km mid-level lapse rates in place (per
    19Z mesoanalysis and an 18Z OAX observed sounding). Agitated CU is
    developing along the NE/SD border, where MLCINH appears to be
    rapidly eroding. The OAX observed sounding shows an elongated
    hodograph with modest low-level curvature, and the 19Z mesoanalysis
    depicts over 50 kts of effective bulk shear, suggesting supercell
    storm modes. Occasional runs of some high-resolution guidance
    members have depicted the initiation of stout, long-lived supercell
    structures originating from this mesoscale scenario.=20

    AS MLCINH continues to erode, supercells should develop over the
    next few hours, accompanied by a severe hail threat. Significant
    severe hail is possible, with 2-3 inch stones possible, and an
    instance of 4+ inch diameter hail cannot be completely ruled out.
    Furthermore, any storms that can anchor to the warm front ahead of
    the surface low may be accompanied by a tornado threat. Convective
    trends will continue to be monitored for the need of a WW issuance.

    ..Squitieri/Hart.. 04/13/2026

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4qrhM7LB3w9UY3JrPHaFTdq5gE-MX17tubVlWt_c7vA8i3gNhUNEzV1_q7NYWPdcounwZvL8o= HAOgnYpJBCcrP5caaM$ for graphic product...

    ATTN...WFO...FSD...OAX...LBF...

    LAT...LON 42379819 41969910 41899934 41969948 42159945 42499918
    42989881 43549813 43649762 43629682 43549640 43349614
    43089605 42819626 42689668 42649736 42499783 42379819=20

    MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 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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