Mesoscale Precipitation Discussion 0573
NWS Weather Prediction Center College Park MD
451 AM EDT Wed Aug 01 2018

Areas affected...FL Panhandle into AL/GA

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

Valid 010850Z - 011450Z

Summary...Bands of heavy showers with isolated thunderstorms will
continue to come ashore across central and eastern portions of the
Florida Peninsula and shift inland into southern portions of
Alabama and Georgia this morning. Rain rates of 2 in/hr are
expected to continue.

Discussion...NEXRAD radars and GOES-16 depict bands of heavy
showers and isolated thunderstorms with local rain rates of 2
in/hr. The main band at 0830Z stretches north from St. George
Island and just east of the Apalachicola River. This activity is
riding north with the warm conveyor belt east of a digging trough
axis over Louisiana. The FL Panhandle is in the preferred right
entrance region of the associated jet (and will be for the next
few days in the stationary long-wave pattern). Precipitable water
values exceed 2.25" according to the 06Z RAP (three standard
deviations above the mean) with surface dewpoints in the mid 70s.

Expect upper level difluence to increase over this area as the
trough digs through 12Z before stalling. Associated increases in
the number of bands coming ashore can be expected through this
time. MLCAPE of 1500-2000 J/Kg at the coast does diminish to
500-1000 J/Kg north of the FL border, though the low level
southerly flow should aide instability transport inland a bit over
the next few hours. The orientation of the bands should allow for
peak intensity to last more than an hour for any particular
location. That is how the 2 in/hr expected should top the 3 inch
3hr flash flood guidance across this area. Due to the high FFG,
expect flash flooding to remain localized through 15Z.

Jackson

ATTN...WFO...BMX...TAE...

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

LAT...LON   31768554 31658364 30848330 29798336 29628359
            29928410 29708440 29488520 30088600 30938608