• MESO: Mesoscale Discussion 0695

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri May 21 20:53:39 2021
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    ACUS11 KWNS 212053
    SPC MCD 212052=20

    Mesoscale Discussion 0695
    NWS Storm Prediction Center Norman OK
    0352 PM CDT Fri May 21 2021

    Areas affected...Parts of western Wyoming and adjacent southeastern

    Concerning...Severe potential...Watch unlikely=20

    Valid 212052Z - 212315Z

    Probability of Watch Issuance...5 percent

    SUMMARY...An isolated supercell or two could pose increasing severe
    weather potential by 4-6 MDT, particularly near/west of the Big
    Piney and Bondurant vicinities into the Jackson Hole area.

    DISCUSSION...In the wake of early afternoon cloud cover and light precipitation, breaks in the overcast may allow a corridor of weak
    to modest boundary-layer destabilization to occur southwest of the
    Wind River Range, particularly near the western slopes of the
    Wyoming Range into the Tetons. With the precipitation contributing
    to at least some low-level moistening, steepening lapse rates, aided
    by insolation beneath weak cold advection aloft, may contribute to
    CAPE on the order of 250-500 J/kg. As this occurs, large-scale
    ascent, beneath difluent/divergent upper flow to northeast of the
    broad and deep mid-level low centered to the east of the Sierra
    Nevada, aided by orographic forcing, may contribute to the
    initiation of isolated to widely scattered thunderstorms by 22-00Z.

    While destabilization may be weak, deep-layer shear beneath 50-80+
    kt southerly mid/upper flow is already strong, and NAM and Rapid
    Refresh soundings have been suggestive that sizable, clockwise
    curved low-level hodographs may develop across this region by late
    afternoon. Thus, it appears that one or two supercells could
    evolve, accompanied by the potential to produce large hail, with
    perhaps some risk for a brief tornado.

    ..Kerr/Guyer.. 05/21/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!o8-NTJ07dnyqMo4I0pD4i169oW8iALjnHYdlHrUqCVNCA9zD9Frel_--Y1Y-lExIHotGfum5$=
    for graphic product...


    LAT...LON 43751121 44151036 42670954 42090989 41981033 42281060
    42641089 43751121=20

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