• MESO: Heavy Rain SFla

    From Weather Alert@454:1/105 to All on Tue Jun 7 16:12:00 2022
    AWUS01 KWNH 071808
    FFGMPD
    FLZ000-072300-

    Mesoscale Precipitation Discussion 0310
    NWS Weather Prediction Center College Park MD
    206 PM EDT Tue Jun 07 2022

    Areas affected...South Florida

    Concerning...Heavy rainfall...Flash flooding possible

    Valid 071800Z - 072300Z

    SUMMARY...Additional development of deep moist convection this
    afternoon is expected across South Florida. Hourly rainfall rates
    2"/hr may lead to areas of flash flooding, particularly in more
    urbanized communities.

    DISCUSSION...Doppler Radar continues to identify a congealed area
    of strong thunderstorms near the Lower Florida Keys and extending
    on north into the Everglades. KAMX base velocities have picked up
    on an outflow boundary tracking north towards the Miami metro area
    with convection beginning to flare up along this boundary, as well
    as along the sea breeze positioned several miles farther inland.
    The atmosphere remains primed to produce torrential rainfall
    rates. Mesoanalysis shows the area has up to 3,000 J/kg worth of
    MLCAPE at these storms disposal and PWs of 2.0-2.3". Area averaged
    soundings at 20Z today from the latest HRRR show mean cloud layer
    vertical wind shear between 30-35 knots, which is largely driven
    by the faster 500-250mb winds aloft. This has likely aided in the
    better organized convection so far just south of the mainland.
    Mean cloud layer winds are also quite weak, generally not topping
    any higher than 10 knots. This is a recipe for building areas of
    convection that can be maintained slightly longer than typical
    pulse storms, and slow storm motions would give storms a little
    longer residency time.

    The upper trough will continue to provide some effective mid-layer
    shear given the presence of the upper trough to the west, as well
    as some diffluent flow aloft. The 12Z HREF did indicate a >40%
    probability area for 3-hr QPF exceeding 3-hr flash flood guidance
    between 18-21Z near and just west of the Miami metro. As the
    outflow boundary advances north, convection will continue to
    ignite additional convection as far north as Lake Okeechobee,
    which will continue into the early evening hours. As daytime
    heating concludes, areas of convection will eventually dissipate.
    South Florida still contains lingering saturated soil throughout
    the region with FLASH CREST soil saturation ranging between 50-75%
    in spots. Along with the urban corridor near Miami and points
    north, it is in these areas with higher soil saturation and in
    more urbanized locations that are most at risk for possible flash
    flooding this afternoon.

    Mullinax

    ATTN...WFO...KEY...MFL...

    ATTN...RFC...SERFC...NWC...

    LAT...LON 26978130 26918065 26537982 25747990 25398020
    25148055 25168105 25408146 25878176 26398157


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