AWUS01 KWNH 041141
FFGMPD
FLZ000-GAZ000-ALZ000-041700-

Mesoscale Precipitation Discussion 0864
NWS Weather Prediction Center College Park MD
741 AM EDT Mon Aug 04 2025

Areas affected...Florida Panhandle into southern Alabama and Georgia

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

Valid 041140Z - 041700Z

Summary...Showers and thunderstorms will gradually expand into the
afternoon and train northward. Rain rates of 2-3"/hr are likely,
which through this training could produce 2-4" of rain with
locally higher amounts. Flash flooding is possible.

Discussion...The GOES-E IR imagery this morning shows multiple
areas of rapidly cooling cloud tops centered along the Florida
Panhandle. These tops are associated with strengthening updrafts
leading to thunderstorms, which are clearly evident on the
regional radar mosaic. Rainfall rates estimated within the deeper
convection has been as high as 2.5"/hr from KTLH, and although the
highest rainfall rates have been offshore so far this morning,
convection has been expanding just inland over the past hour.

The environment across the region is extremely favorable for heavy
rainfall. A surface stationary front analyzed by WPC is serving as
a focus for low-level convergence to enhance ascent, with
additional lift occurring along a frictional axis near the
Gulf/land interface, and downstream of a weak shortwave
approaching the coast. This ascent is working into robust
thermodynamics to support the heavy rain rates, with PWs measured
via GPS as high as 2.3 inches, well above the 90th percentile and
approaching the daily records, with MUCAPE already above 1000
J/kg, although the most substantial instability is right along the coast.

The sharp gradient of instability is limiting the inland extent of
heavy rainfall so far, but over the next few hours more widespread
convection should spread northward. This is due in part to
increasing southerly flow as the region remains pinched between a
ridge to east centered over the Atlantic Ocean, and a trough axis
positioned over Mississippi. The persistent southerly flow to draw
higher PW/CAPE northward will combine with daytime heating to
allow for more robust thermodynamics to expand across the area. As
this occurs, convection should rapidly spread across much of the
area while intensifying, which is supported by most available
CAMs, with 2-3"/hr rain rates likely as reflected by HREF
neighborhood probabilities and the 15-min HRRR rainfall
accumulation product. With nearly unidirectional 850-500mb flow
and 850mb winds exceeding the mean 0-6km wind, storms should
rapidly expand in the next few hours and train south to north,
leading to multiple rounds of convection which could produce 2-4"
of rain with locally higher amounts possible, especially from
Apalachicola through the Emerald Coast.

Additionally contributing to the increasing flash flood risk is
recent rainfall that has been 2-4" with locally as much as 6" the
past 48 hours according to MRMS. This has lowered 3-hr FFG,
especially across southern AL and southern GA, to 2-2.5". While
FFG remains high along the Florida Panhandle, any training of
these rain rates moving atop urban areas could additionally
quickly result in runoff and instances of flash flooding.

Weiss

ATTN...WFO...BMX...FFC...MOB...TAE...

ATTN...RFC...ALR...NWC...

LAT...LON   33108546 32948460 32668412 31978387 30808387 
            30198412 29858443 29668490 29798550 30018573 
            30168663 30138702 30188746 30378760 30768706 
            31098605 31978586 32688574 
$$
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