496
AWUS01 KWNH 181212
FFGMPD
FLZ000-GAZ000-ALZ000-181710-

Mesoscale Precipitation Discussion 0288
NWS Weather Prediction Center College Park MD
811 AM EDT Sat May 18 2024

Areas affected...FL Panhandle...Southeast AL...Southwest GA

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

Valid 181210Z - 181710Z

SUMMARY...Numerous showers and thunderstorms advancing inland from
the northern Gulf of Mexico will yield heavy rainfall totals over
the next several hours for the FL Panhandle, parts of southeast AL
and southwest GA. This coupled with locally wet antecedent
conditions will likely foster areas of flash flooding.

DISCUSSION...The early morning GOES-E IR satellite imagery shows
clusters of cold topped convection (-65C to -70C) over the
northern Gulf of Mexico that are beginning to overspread areas of
the FL Panhandle. The activity is focusing along and out ahead of
a front as a wave of low pressure advances northeast along it and
also interacts with a very moist and unstable airmass pooled over
the region.

MLCAPE values of 1500 to 2500+ J/kg are focused all across the
warm sector areas of the northern Gulf of Mexico northeastward
through the FL Panhandle, southeast AL, and into southwest GA. PWs
across the region are generally in the 1.75 to 2.0 inch range with
a corridor of deep tropical moisture focused along and just ahead
of the front. This coupled with increasing deep layer forcing
associated with right-entrance region upper-jet dynamics and
favorable shear profiles is expected to maintain a rather well
organized convective threat through the morning hours that will
overspread the FL Panhandle, southeast AL and southwest GA.

Rainfall rates should be very high and capable of reaching
2.5"/hour given the level of instability/moisture and persistent
forcing through the vertical column. Given the orientation of the
convection relative to the deeper layer steering flow, there is
likely to be some cell-training, and with these high rainfall
rates, some storm totals this morning may be particularly heavy.

The morning hires model consensus may be a bit underdone with the
rainfall potential given the ingredients that are in place. Given
the current satellite and radar trends, some rainfall totals of 4
to 6 inches with isolated heavier amounts will be possible. The
heaviest totals will be over the FL Panhandle, with somewhat
lesser amounts over southeast AL and southwest GA.

Many of these areas have already seen heavy rainfall over the last
12 to 18 hours, and these additional rains are likely to foster
areas of flash flooding with locally considerable/significant
impacts possible.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...FFC...JAX...MOB...TAE...

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

LAT...LON   31958306 31738222 31288235 30968339 30758396
            30468465 30208535 30118574 30438724 30838745
            31098699 31568543 31888408