636
AWUS01 KWNH 131004
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-131430-

Mesoscale Precipitation Discussion 0263
NWS Weather Prediction Center College Park MD
604 AM EDT Mon May 13 2024

Areas affected...central Gulf Coast

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

Valid 131002Z - 131430Z

SUMMARY...Flash flooding is expected for portions of the central
Gulf Coast region over the next few hours from west to east
training of heavy rain. 2-4 inches within a 2-3 hour window will
be possible.

DISCUSSION...At 0930Z, a slow moving warm front was analyzed along
the central Gulf Coast with surface observations showing
approximately a 5 degree jump in dewpoint over the past 3 hours
with veering winds. Isentropic ascent continued to support largely
elevated thunderstorms to the north of the front, from
north-central LA into south-central MS. However, the leading edge
of convection has evolved into a linear segment, with strong to
severe winds reaching the surface. Thunderstorms that were located
farther away from the surface warm front, such as north-central
LA, were estimated to be rooted higher up above the surface,
closer to 850 mb per area RAP analysis soundings.

The linear segment moving through south-central MS was oriented NE
to SW, moving generally to the east at 40 kt over the past 3
hours, but with some southward nudging over LA with the trailing
edge extending back toward the southwest. This general motion
(ESE) is expected to continue in the short term, ahead of a
700-500 mb shortwave trough seen on Layered PW imagery, associated
with a strong gradient in moisture, extending from east-central AR
to southeastern TX at 09Z.

30-35 kt of 850-700 mb layer winds from the SW or SSW will
continue to support ascent atop the surface warm front in the
short term with convection to its north possible stalling the warm
front`s northward progress due to rain-cooled air to its north.
ESE movement of convection is expected to continue over the next
3-4 hours along with the likelihood for training from 1 to 2+
in/hr rainfall rates and 2-4 inches in 2-3 hours time as heavy
rain echoes align from west to east.

Portions of this area, especially LA into southwestern MS, have
increased soil moisture and greater potential for flash flooding
due to recent heavy rainfall, but locations east of roughly I-55
have been drier and are likely less susceptible to flash flooding,
with the exception of urban locations.

Otto

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

ATTN...WFO...BMX...JAN...LCH...LIX...MOB...SHV...TAE...

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

LAT...LON   32428854 32308689 31578598 30098643 30118909
            30159032 30199195 30389291 30709314 31599304
            31809270 32099119 32308965