• MESO: Mesoscale Discussion 1162

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Jul 6 18:06:34 2021
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    ACUS11 KWNS 061806
    SPC MCD 061806=20

    Mesoscale Discussion 1162
    NWS Storm Prediction Center Norman OK
    0106 PM CDT Tue Jul 06 2021

    Areas affected...northeast Nebraska southeast South Dakota and
    portions of Minnesota Iowa and Wisconsin

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

    Valid 061806Z - 062000Z

    Probability of Watch Issuance...60 percent

    SUMMARY...Strong/severe storms developing ahead of and along a
    remnant MCV/stationary front through the upper Midwest may pose a
    severe risk as they move northeast through the day. Severe hail and
    damaging wind gusts appear to be the mean threats. Convective trends
    are being monitored as a weather watch may be needed.

    DISCUSSION...As observed by regional radar mosaics and midday
    visible imagery, a cluster of elevated thunderstorms has shown signs
    of organization/intensification this morning across portions of
    Nebraska, and south Dakota. Likely driven by enhanced lift ahead of
    the MCV and along the stationary front, these storms should
    gradually become surface based as they track northeastward.
    Downstream, clearing skies south of the front have allowed
    temperatures to warm into the low to mid 80s F across southern
    Minnesota and far northern Iowa. To the north, residual cloud cover
    has limited heating so far, but breaks in the clouds should allow
    some warming through the afternoon. With the warm temperatures and
    dewpoints in the mid to upper 60s F, moderate buoyancy (1500-2000
    J/kg MLCAPE) is forecast to materialize despite modest mid-level
    lapse rates. As lift from the approaching MCV increases, additional thunderstorm development appears likely along and north of the
    stationary front through southern Minnesota and farther southwest
    along the surging cold front in central Nebraska. Regional 12z
    soundings and VWPs show enhanced mid-level shear associated with the
    MCV across portions of South Dakota and northeastern Nebraska. 30-35
    kts of effective shear should support organized short line segments
    and a few supercells this afternoon. Hail and damaging wind gusts
    appear to be the most likely threat, though a brief tornado will be
    possible with greater low-level shear from backed surface flow along
    the boundary through southern Minnesota and western Wisconsin.
    Upscale growth into a forward propagating MCS appears likely later
    this evening as storms congeal heading into southwestern Wisconsin.
    A somewhat more organized wind threat may evolve there if a deeper
    cold pool can become established. Given the favorable environment
    and potential storm coverage, convective trends are being monitored.
    A weather watch may be needed over portions of the area later this afternoon/evening as convection becomes more organized.

    ..Lyons/Guyer.. 07/06/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!qDSeg-YJCYa7Zmpy6-l1MD0S1uS1aQiM2DgUooiPq9g-EX_qagJB6REjaKUg_dPeo9JgAz1-$=
    for graphic product...


    LAT...LON 44919120 44709061 43959055 43539122 43509241 43529407
    43489521 43099614 42439715 41199892 40960031 41070055
    41530058 42739936 44299773 44589661 45049479 45169276

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