830
AWUS01 KWNH 121906
FFGMPD
TXZ000-OKZ000-130104-

Mesoscale Precipitation Discussion 0660
NWS Weather Prediction Center College Park MD
305 PM EDT Sat Jul 12 2025

Areas affected...TX

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

Valid 121904Z - 130104Z

Summary...Expanding convection ahead of an MCV will result in
isolated to scattered flash flooding through the afternoon across
much of central to northern Texas.

Discussion...Two distinct MCVs are evident on visible satellite
imagery...one across portions of western OK and another over the
southern TX Panhandle. It is the latter one that will likely be
the main player in an expanding thunderstorm threat over central
and north TX this afternoon and evening. These are small scale
features that can be difficult for models to resolve with much
lead time, thus not too surprising that recent high res model runs
are not doing a great job with the ongoing activity and evolution
going forward. Given the downstream environment, the 17z HRRR in
particular seems much too dry, oddly killing convection despite
the MCV and downstream instability pool. Recent runs of the
experimental RRFS are seemingly handling things better, albeit
maybe progressing convection too quickly off to the east.

The environment downstream of the MCV has a broad are of MLCAPE
around 2000 J/KG and PWs over 1.6" (should continue to increase
towards 1.75"). Deep layer wind shear is weak, but the flow at
300mb is broadly diffluent, which combined with the MCV should
help sustain convection long enough for locally heavy rain. The
downstream environment is a bit messy, with subtle boundaries and
some ongoing convection. It seems likely that we will see some
cell merger activity in this environment as convection closer to
the MCV runs into the more isolated downstream cells...which
should locally increase the flash flood risk.

While isolated flash flooding is probable, there remains
uncertainty on the coverage of the threat through 01z. Most
indications would suggest just this isolated coverage of flash
flooding, as some eastward propagation and pulsing nature of
convection preventing a more widespread risk through 01z. However
still certainly the potential for localized higher end
impacts...and upwind propagation vectors would support
backbuilding/slowing of convection. Thus if activity is able to
organize more than current models indicate, then a more organized
flash flood risk could certainly evolve by 01z. In addition,
guidance is trending towards the MCV being a focus for slow
moving/backbuilding convection tonight (after the expiration of
this MPD). So we will need to closely monitor observational and
model trends through the afternoon and evening...as these
nocturnal MCV driven events can produce a significant flash flood
threat. Additional MPDs will be issued as needed as the risk
evolves.

Chenard

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

ATTN...WFO...EWX...FWD...LUB...MAF...OUN...SJT...

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

LAT...LON   34259748 34089696 34039634 33579616 31859654
            31059756 30679910 30420051 30370084 30440152
            31440136 31670128 32570060 33359935 34189838