• Day 1 Enhanced Risk MN/WI

    From Mike Powell@618:250/1 to All on Wed Jun 12 08:14:00 2024
    ACUS01 KWNS 121204
    SWODY1
    SPC AC 121202

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0702 AM CDT Wed Jun 12 2024

    Valid 121300Z - 131200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    AND EVENING ACROSS PORTIONS OF NORTHEAST MINNESOTA AND NORTHWEST
    WISCONSIN...

    ...SUMMARY...
    Scattered severe thunderstorms capable of very large hail, damaging
    wind gusts, and a few tornadoes will be possible across parts of the
    Upper Midwest late afternoon and early evening.

    ...Southern MN/WI early today...
    Morning water vapor imagery shows a fast-moving shortwave trough
    over the western Dakotas. Lift and enhanced low-level
    thermal/moisture advection ahead of the trough has resulted in
    scattered thunderstorm development over western MN and eastern SD.
    These storms may persist through the morning, tracking across
    central/southern MN by early afternoon with some risk of large hail.
    Daytime heating and increasing low-level moisture will eventually
    result in moderate CAPE and a risk of organized strong/severe
    thunderstorms - mainly from central MN eastward after 18z. These
    storms may grow upscale and track into central WI before weakening,
    posing a continued risk of damaging winds and hail.

    ...Northern MN/WI later today...
    In the wake of the aforementioned morning convection, strong daytime
    heating and moisture advection will result in a corridor of moderate
    CAPE across central/northeast MN by mid/late afternoon.
    Temperatures west of this area will heating to near 90F, with
    forecast soundings showing little cap, very steep mid-level lapse
    rates, and MLCAPE values around 3000 J/kg. Large scale forcing will
    be subtle, leading to the development of discrete supercells.
    Several overnight CAM runs suggest intense storms that form will
    track into the Arrowhead region of MN and areas around Duluth by
    early evening, posing a risk of very large hail, damaging winds, and
    a few tornadoes. Forecast soundings show substantial low-level
    shear with effective SRH values of 300+ m2/s2. It is uncertain how
    the early storms over southern MN will affect moisture return. If
    high dewpoint air can make it into the ENH risk area, higher tornado probabilities may become warranted. These storms will likely
    congeal and spread eastward across northern WI during the evening
    with a continued risk of damaging winds and some hail.

    ..Hart/Bentley.. 06/12/2024

    $$
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