427
AWUS01 KWNH 130525
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-130930-

Mesoscale Precipitation Discussion 0262
NWS Weather Prediction Center College Park MD
124 AM EDT Mon May 13 2024

Areas affected...eastern TX into LA and central MS

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

Valid 130523Z - 130930Z

SUMMARY...Flash flooding appears likely within portions of the
South tonight, extending from eastern TX into LA and
western/central MS through 09Z. Periods of training are expected
to produce 2-4 inch totals in a 3 hour (or less) window.

DISCUSSION...05Z radar imagery over eastern TX into north-central
LA showed a few clusters of thunderstorms extending in a line from
east-central TX (Brazos/Madison County) into north-central LA,
south of I-20 (Natchitoches/Winn/Caldwell parishes). These storms
were elevated, likely rooted between 925-850 mb, based on area 00Z
soundings and recent RAP analysis soundings. Convective
development in the vicinity of I-45 sine 02Z appears to have been
sparked, in part, due to the approach of an 850-700 mb moisture
gradient, oriented NE to SW, observed in Layered PW imagery to be
moving east, with drier air to its west. Instability over the
region was ample to support convection for most locations but
dropped off below 500 J/kg in northeastern LA and central MS per
05Z SPC mesoanalysis and RAP data.

The continued eastward advancement of a mid-level trough over the
central Plains is expected to push the 850-700 mb moisture
gradient eastward across east-central TX through 12Z. Additional
convective development to the south of ongoing activity will be
possible but the main axis of forcing to the north is forecast to
shift toward the northeast over the next few hours, with
instability increasing into northeastern LA and MS with low level
warm advection and northward lifting of the surface warm front,
located over southeastern TX/southwestern LA at 05Z. Thunderstorms
are expected to maintain an overall movement from west to east but
exhibiting periods of training (1-2 in/hr) and the likelihood for
some areas to see 2-4 inches in 3 hours or less.

MRMS rainfall estimates over the past 12 hours show portions of
the Piney Woods region of eastern TX into central LA having picked
up 2-5 inches of rain. These recent rains combined with a wetter
than average May and elevated soil moisture values from NASA SPoRT
imagery from 23Z Sunday suggest the region will be more
susceptible to flash flooding than average. Expectations are that
2-4 inches of rain in 2-3 hours will result in some areas of flash
flooding through 09Z.

Otto

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

ATTN...WFO...FWD...HGX...JAN...LCH...LIX...SHV...

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

LAT...LON   33229035 32938946 31908963 30899073 30189339
            30229546 30659607 31399608 32299493 32749333