294
AWUS01 KWNH 130226
FFGMPD
TXZ000-130825-

Mesoscale Precipitation Discussion 0665
NWS Weather Prediction Center College Park MD
1025 PM EDT Sat Jul 12 2025

Areas affected...Central Texas

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

Valid 130225Z - 130825Z

SUMMARY...A serious risk of high-impact flash flooding from
slow-moving, and locally training showers and thunderstorms will
exist later tonight across central TX, including portions of the
Edwards Plateau/Hill Country.

DISCUSSION...The GOES-E Proxy Visible satellite imagery shows a
slow-moving vort center gradually drifting east across the Concho
Valley which overnight will eventually advance into the broader
Hill Country region. Based on the latest CIRA-ALPW data, this
energy is embedded within a concentrated corridor of deeper
moisture lifting up across central TX, with strong concentrations
seen in the 850/500 mb layer with overall values of 1.5 to 1.75+
inches.

Meanwhile, the airmass more broadly pooled across the Hill Country
region is quite unstable with MLCAPE values of 1500 to 2500 J/kg.
This instability is seen pooling along a weak surface trough out
ahead of a stationary front, and this coupled with the arrival of
the aforementioned vort energy along with a gradually increasing
southerly low-level jet should help drive developing areas of
showers and thunderstorms with high rainfall rates.

A nocturnal tightening of the mid-level vort energy along with
increasingly convergent flow along its southern and eastern flanks
near the surface trough will favor convection growing gradually
upscale, but in a very concentrated manner in a southwest to
northeast fashion across central TX. This region will also be in
the right-entrance region of an upper-level jet to further support
ascent for convection.

Rainfall rates are expected to be on the order of 2 to 4
inches/hour with the stronger storms, and the latest HRRR/RRFS
guidance along with support from the 18Z HREF and 12Z REFS suites
support these rates. An excellent environment will develop later
tonight for back-building and training convection, with slow
cell-motions. Favorable Corfidi vectors with weak steering flow
are expected to align that will facilitate this convective
evolution especially after midnight.

Some rainfall totals by 08Z (3AM CDT) may reach as high as 4 to 6+
inches, but with additional very heavy rainfall expected after
this time frame going through dawn. A serious risk of high-impact
flash flooding is expected overnight across the sensitive Hill
Country region, with dangerous and life-threatening flash flooding
likely by later tonight. Additional MPDs will be issued
accordingly as this event unfolds.

Orrison

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

ATTN...WFO...EWX...FWD...MAF...SJT...

ATTN...RFC...FWR...NWC...

LAT...LON   32939718 32759622 32189589 31489612 30639713
            29949852 29579995 29690106 30260173 30930152
            31320091 31669989 32209880