373
AWUS01 KWNH 031631
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-032230-

Mesoscale Precipitation Discussion 0579
NWS Weather Prediction Center College Park MD
1231 PM EDT Thu Jul 03 2025

Areas affected...Vicinity of the Red River Valley of the South

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

Valid 031630Z - 032230Z

Summary...Showers and thunderstorms will develop along a decaying
frontal boundary and train through the afternoon. Rainfall rates
may pulse up above 2"/hr at times, leading to 1-2" of rainfall
with locally higher amounts above 3". Flash flooding is possible.

Discussion...The regional radar mosaic late this morning shows a
rapid uptick in convection developing along a decaying stationary
front aligned near the Red River Valley of the South. Recent radar
estimated rain rates from KTLX and KFWS have been as high as
1.5"/hr within fresh convection, with storm motions generally of
to the north at 10 kts.

The environment is becoming increasingly favorable for heavy rain
containing convection, with a ribbon of MLCAPE exceeding 1000 J/kg
overlapping PWs as high as 2 inches, which is well above the 90th
percentile for the date, and a daily max at KOUN according to the
SPC sounding climatology. Modest low-level S/SW winds measured via
VWPs at 10-20 kts lifting into the decaying front are resulting in
increasing isentropic ascent, which is acting together with a weak
impulse moving into North Texas and broadly diffluent 300mb flow
to provide deep layer ascent. This lift occurring into these
favorable thermodynamics will continue to support increasing
coverage and intensity of thunderstorms through the aftn.

The high-res CAMs are again struggling to handle the ongoing
activity, although the ensembles, both HREF and REFS, appear to be
usable. These ensembles both suggest that coverage of 1"/hr (and
2"/hr) neighborhood rain rate probabilities will rapidly rise
during the next few hours in a NW to SE oriented axis in the
vicinity of the decaying front. With ascent remaining in place and
thermodynamics becoming increasingly robust later today (SBCAPE
approaching 2000 J/kg), thunderstorms should remain supported and
intensify. This is suggested by HREF and REFS probabilities for
2"/hr rates reaching 25-35%, coincident with HRRR 15-min rainfall
exceeding 0.75" at times (brief 3"/hr rates). Although the models
disagree on where the heaviest rain will occur, the maximum
convergence just north of the boundary should be favored, which is
also where Corfidi vectors are aligned most obliquely right of the
mean flow to suggest enhanced training from NW to SE as the line
forms and advects slowly northward.

0-10cm RSM from NASA SPoRT is generally around 50% south of the
Red River, but as much as 80% to the north, suggesting that OK is
more vulnerable than TX today. This is also where the, albeit
modest, FFG exceedance probabilities exist. While that area may be
most susceptible today, any place that receives training of these
more intense rain rates could experience instances of flash
flooding through the aftn.


Weiss

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

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

ATTN...RFC...FWR...ORN...TUA...NWC...

LAT...LON   35959870 35539757 34169560 33269406 33179395
            32699348 32269335 31989358 31839419 32089574
            32769774 33449901 34419950 35509952