092
AWUS01 KWNH 121519
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-122031-

Mesoscale Precipitation Discussion 0030
NWS Weather Prediction Center College Park MD
1018 AM EST Wed Feb 12 2025

Areas affected...Lower Missisippi Valley

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

Valid 121518Z - 122031Z

Summary...Showers and thunderstorms will expand in coverage and
begin to train from SW to NE through the afternoon. Rainfall rates
in excess of 1"/hr will become more common, which through training
may produce 2-3" of rain. This could lead to instances of flash
flooding.

Discussion...The regional radar mosaic this morning depicts two
areas of heavy precipitation spreading across portions of the Gulf
Coast and lower Mississippi Valley states. A meandering stationary
front analyzed by WPC draped from northern MS into eastern TX is
providing focus for a corridor of convection, while a more broad
warm front slowly lifting across LA/MS is helping to spawn warm
advection showers and isolated thunderstorms. In general, rainfall
rates this morning have been between 0.25 and 0.5 inches per hour,
but a few embedded 1"/hr cells have recently been observed via
MRMS radar estimates. This has produced locally 2-3" of rain in
the past 6 hours, and a few flood advisories are currently in
effect.

As the morning progresses into the afternoon, upstream troughing
across the Central Plains will amplify, with synoptic ascent
becoming enhanced across the region through height falls, PVA, and
an intensifying jet streak aloft. Together, this will help lift
the warm front more steadily northward, leading to greater
instability drawing northward and impinging into the stationary
front. This is reflected by impressive moisture transport vector
convergence later this morning, especially from northern LA into
northern MS. As CAPE climbs to 500-1000 J/kg, this will support
more widespread convective rain rates which the HREF indicates
have a 20-40% chance of exceeding 1"/hr, with short term rain
rates potentially eclipsing 2"/hr as shown by the HRRR 15-min
fields. Storm motions will remain quick on 850-300mb winds of
40-60 kts, but organization along this boundary and some
backbuilding into TX will support training. This suggests that
despite the fast motion of individual cells, some areas may pick
up 2-3" of rain.

The soils across this region are generally saturated as noted via
NASA SPoRT 40cm soil moisture that is around the 90th-95th
percentile. This has reduced FFG to just 1-2"/3 hrs, or less, in
many areas, for which the HREF suggests has a 20-50% chance of
exceedance in the next few hours. This is further reflective of
the isolated potential for flash flooding into this afternoon.


Weiss

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

ATTN...WFO...JAN...LCH...LZK...MEG...SHV...

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

LAT...LON   34238926 33958850 33368831 33048848 32578930
            32039023 31339199 31039338 31069381 31169418
            31549474 32279439 32789356 33479207 33969096