931
AWUS01 KWNH 121759
FFGMPD
TXZ000-OKZ000-122300-

Mesoscale Precipitation Discussion 0259
NWS Weather Prediction Center College Park MD
158 PM EDT Sun May 12 2024

Areas affected...Red River Valley of Northern TX...Adj Southern
OK...

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

Valid 121800Z - 122300Z

SUMMARY...Broad isentropic warm advective ascent to support
back-building within a favorable environment for training of
embedded elevated convection.  Spots of 2-3" in short-duration
over saturated soils, localized incidents of flash flooding
possible.

DISCUSSION...GOES-E WV depicts the base of the larger scale
positive tilt trough is emerging from NE NM/SE CO, while a
southern stream shortwave moves through the downstream subtle
ridging over Eastern TX.  As such, there is solid broad scale
ascent within diffluent flow aloft supporting the slant-wise
ascent over the 850mb boundary that bisects TX from SE to near CDS
before angling north along the eastern portions of the Northern TX
Panhandle.  VWP from DYS and DFW sites, denote strong southerly
30-35kt 925-850mb flow which is providing modest warm advection of
unstable air to allow MUCAPE to 1000-1500 J/kg across the Big
Country into North Texas; though a very stable layer exists over
South-central to Southwest Oklahoma.  This instability supports
the fractured/scattered nature of the thunderstorm development
across the area though some embedded cells capable of intense
short-term rates.

The question will be duration, but above the development region
the turning in the ascent channel quickly veers to southwesterly
through a bulk of the steering depth of thunderstorms that have
developed over this FGEN boundary. This is favorably oriented to
support a training/repeating environment.  In addition, there is a
fair saturated mid-level environment to help maintain rainfall
efficiency of the thunderstorms that do lift over the boundary.
Given the instability potential for rates up to 1.5"/hr.  With
upstream height-falls and exiting wave, flow regime may weaken
slightly but is probable to maintain the isentropic ascent and
training for a few more hours, with back-building or upstream
regeneration along the boundary.   As such, spots of additional
2-3" are probable.

Normally, this would not be of great concern, but recent heavy
rainfall in the region has resulted in 0-40cm saturation
percentages to be well above normal (in the 95th percentile) and
generally about 60-70% per NASA SPoRT LIS product.  As such, there
will be limited infiltration and greater than normal runoff from
this spotty 2-3" and localized scattered incidents of flash
flooding are considered possible.

Gallina

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

ATTN...WFO...FWD...OUN...SHV...SJT...TSA...

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

LAT...LON   34369874 34319711 34069637 33929558 33709496
            33139479 32569520 32229672 32389832 32999913
            33989936