AWUS01 KWNH 011254
FFGMPD
FLZ000-ALZ000-MSZ000-011800-

Mesoscale Precipitation Discussion 0365
NWS Weather Prediction Center College Park MD
854 AM EDT Sat Jun 01 2024

Areas affected...central Gulf Coast into southern AL

Concerning...Heavy rainfall...Flash flooding likely

Valid 011253Z - 011800Z

SUMMARY...Intense rainfall rates are likely to continue areas of
flash flooding across the FL Peninsula over the next few hours
with rainfall rates over 3 in/hr at times. Additional convective
development farther west toward the southern MS/AL border may also
produce flash flooding later this morning.

DISCUSSION...An area of intense rainfall has been ongoing over
portions of the central Gulf Coast since ~06Z with several
Wunderground.com reports of 4 to 8+ inches of rain occurring from
near Mobile Bay into Santa Rosa and Okaloosa counties in the
western FL Panhandle. 3 hour rainfall has been in the 4 to 7+ inch
range with rates of 1 to 1.5 inches in 15 minutes (through 12Z).
Low level flow has been channeled northward between a westward
moving dry intrusion over the eastern Gulf Coast and an eastward
advancing mid-level trough extending from MO to the central Gulf
Coast. The moist airmass (PWATs approaching 2 inches just south of
the Gulf Coast) has been transported north of an effective front,
marked by a sharp gradient in MLCAPE located across the FL
Panhandle. Upper level flow was fairly diffluent ahead of the
upper level reflection of the trough axis centered over MS at 12Z,
aiding in strong vertical ascent.

As the mid-level trough over the central U.S. advances east over
the next 6 hours and the advection of drier low level air
continues to push westward across the eastern Gulf, expectations
are for the low level confluence axis to nudge eastward and for
some weakening of low level moisture transport over the northern
Gulf. This should tend to allow the axis of ongoing heavy rain,
with rainfall rates occasionally peaking above 3 in/hr, to track
east toward the Apalachicola River with subsequent convective
development possibly shifting into the northern Gulf of Mexico.
How long it takes for this to happen is a bit uncertain though,
with the low level convergence axis possibly holding on a bit
longer than short term models are indicating, maintaining heavy
rain for another few hours. This could result in an additional 4-8
inches of rain for isolated locations within the FL Peninsula
through 18Z and possibly significant flash flooding.

Farther to the west, lift ahead of the upper trough axis and
increasing instability with mostly clear skies over southern MS/AL
may allow for the redevelopment of thunderstorms by 16-18Z in the
vicinity of the existing instability gradient. These cells will
have the potential for high rainfall rates and areas of flash
flooding with rates of 2 to 3+ in/hr.

Otto

ATTN...WFO...BMX...LIX...MOB...TAE...

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

LAT...LON 32018595 31788534 30738497 29998508 29588530
29538561 29988627 30068730 30018843 30068876
30778902 31408825 31788714

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