Mesoscale Precipitation Discussion 0900
NWS Weather Prediction Center College Park MD
147 PM EDT Wed Sep 26 2018

Areas affected...Central/Northern LA into Central MS

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

Valid 261746Z - 262246Z

Summary...Line of slow moving convection across central LA into
central MS will drift northward in an anomalously high moisture
environment and possibly lead to flash flooding this afternoon.

Discussion...Latest visible satellite imagery showed a couple of
boundaries converging across portions of central LA into central
MS, one associated with a line of convection moving northward with
another tied to a cold front sagging southward.

Regional radars depicted a slow moving line of convection was
producing widespread 1 to 1.5 in/hr rates with localized 2-3 in/hr
rates across east-central LA into west-central MS. Recent totals
showed pockets of 1 to 3 inches.

Latest hi-res models have a poor handle on the evolution of this
convection across the area. It seems that the line will favor the
instability pool (MLCAPE of 2000 J/kg) and continue drifting
northward over the next several hours. This remains in an area of
high PWATs (1.8 to 2.1 inches) with very warm cloud depths
expected (4.0-4.5 km) so extremely efficient rain processes will
continue.

Rain rates of 1-2 in/hr will be possible through the afternoon
hours with additional rainfall of 2-4 inches possible from central
MS westward into central LA. The main limiting factor against more
widespread flash flooding is relatively high FFG across the area,
though there are pockets of wetter soils that will need to be
closely monitored.

Taylor

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...

LAT...LON   33169057 33069014 32828987 32438983 31988997
            31769026 31589060 31109148 30989291 30999308
            31029335 31099363 31219385 31319406 31459422
            31689433 31949440 32249439 32559424 32769387
            32929183