AWUS01 KWNH 191227
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-191730-

Mesoscale Precipitation Discussion 0660
NWS Weather Prediction Center College Park MD
827 AM EDT Fri Jul 19 2024

Areas affected...Central Gulf Coast

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

Valid 191226Z - 191730Z

Summary...Efficient thunderstorms with rainfall rates upwards of
3"/hr at times are expected to persist this morning. Repeating of
these storms may lead to some flash flooding.

Discussion...Radar and IR imagery across the Central Gulf Coast
continue to track an axis of showers and thunderstorms lifting
northeastward at around 10-15 kts. A particularly efficient
cluster of thunderstorms southwest of Mobile, AL contained
estimated rainfall rates approaching 3"/hr earlier as individual
cells merged near the coastline recently.

This corridor of activity is likely forced by 1) an approaching
shortwave to the west and 2) a diffuse northeast to southwest
oriented offshore convergence axis, which is aligned with the mean
wind vector. Amid the forcing from this low-level boundary, the
RAP suggests a very moist and unstable airmass will continue to
push inland along a tight gradient to maintain efficient rainfall
rates, with 2.1-2.25" PWATS and 2000-2500 J/kg of MUCAPE expected
along the coastline over the next few hours.

While the rainfall footprint with this activity will be somewhat
"popcorn" owing to a lack of appreciable vertical shear, the very
efficient rainfall production will support some flash flooding
risk this morning as cells repeat along the lingering convergence
axis. CAM guidance is a bit all over the place with initializing
the ongoing storms, although several pieces of high-res guidance
(11Z HRRR, ARWs, FV3, and RRFS) are quite wet and suggest rainfall
amounts of 3-5" are possible through this morning. While 1-3 HR
FFGs are quite high in the area (2.5-4"), repeating instances of
these efficient storms could realize these higher end amounts on a
localized basis, indicating some flash flood threat through this
morning.

Asherman

ATTN...WFO...LIX...MOB...

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

LAT...LON 30978818 30878667 30148686 29398840 28818930
29049008 29509009 30308934
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