• MESO: Mesoscale Discussion 0371

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Apr 12 06:13:46 2021
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    ACUS11 KWNS 120613
    SPC MCD 120613=20

    Mesoscale Discussion 0371
    NWS Storm Prediction Center Norman OK
    0113 AM CDT Mon Apr 12 2021

    Areas affected...Portions of the Florida Keys.

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

    Valid 120613Z - 120845Z

    Probability of Watch Issuance...5 percent

    SUMMARY...Isolated severe hail is possible from convection moving
    southeastward across mainly the lower/middle Keys for a few more
    hours. A watch is unlikely.

    DISCUSSION...Surface mesoanalysis depicts an outflow boundary --
    produced by the earlier/severe peninsular MCS -- progressing
    southward over the area from the central Bahamas to the Cuban
    coastline near MUVR/Varadero, then northwestward across the Straits
    of Florida southwest of EYW. The western part of the boundary,
    northwest of Varadero, is decelerating and may stall and retreat
    northward the next few hours.=20=20

    VWP from BYX radar indicates the cold pool is shallow, with
    southerlies at 850 mb supplying richly moist inflow to elevated
    convection north of the boundary. That includes a supercell with
    occasional MESH indicators of severe hail, located about 40 NNE of
    EYW at 06Z, and moving southeastward generally toward the
    Marathon/Seven Mile Bridge area. Other isolated strong-severe
    thunderstorms also may form in this regime, where modified RAOBs and
    forecast soundings suggest around 500-1000 MUCAPE atop the stable
    boundary layer. Favorable vertical shear is apparent atop the cold
    pool as well, in the form of veering with height and 50-60-kt
    effective-shear magnitudes. The cold pool should become shallower
    with time -- especially around the lower Keys -- indicating the
    potential for localized downdraft gusts approaching severe limits to
    penetrate to the surface as well.

    ..Edwards.. 04/12/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!tVeggQCZ_nP6IyeSBKsHf4URff-O1da8AnLnz28Ndh1IfhFJu6bhtAumIYxTbuwUyjKSm8_F$=
    for graphic product...


    LAT...LON 24888070 24668100 24568159 24518212 24618294 24698291
    24598211 24618180 24718169 24718158 24848149 24798125
    24738118 24818091 24888070=20

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