621
AWUS01 KWNH 200542
FFGMPD
TXZ000-201010-

Mesoscale Precipitation Discussion 1233
NWS Weather Prediction Center College Park MD
1241 AM EST Thu Nov 20 2025

Areas affected...portions of central TX

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

Valid 200540Z - 201010Z

Summary...Isolated to widely scattered instances of flash flooding
will be possible over portions of central TX including the Hill
Country through 10Z. Localized totals of 2 to 4+ inches may occur
over a relatively short period of time.

Discussion...Regional radar imagery through 0530Z showed widely
scattered coverage of thunderstorms over central TX with an
increasingly concerning cluster near/south of JCT with only small
net-movement over the past hour. The environment over central TX
contained anomalous precipitable water values of 1.3 to 1.7 inches
and 500-1500 J/kg MLCAPE (SPC mesoanalysis and area soundings from
00Z) with moisture contributions from the tropical eastern Pacific
in the mid/upper levels and Gulf of America in the lower levels.
0-6 km mean layer winds were a progressive 20-30 kt toward the
northeast but sufficient speed shear was present for organized
cells and slower storm motions right of the mean wind.

While larger scale forcing ahead of a strong mid to upper level
trough/closed low over the CA/AZ border was still well west of TX,
the low level response out ahead of this feature was SSE 925-850
mb winds of 20-30 kt with increasing low level moisture values
into central TX since Wednesday evening as seen on OSPO LPW
imagery in the surface-850 mb layer. Transient axes of low level
convergence and upslope flow into the Edwards Plateau are expected
to continue to support small clusters of thunderstorms with mean
movement off toward the northeast. However, there will likely be
areas of upstream convective redevelopment which will allow for
training and repeating cells at times. Peak hourly rainfall of 1
to 2 inches (locally higher) is expected within SW to NE axes of
training with 3-hr totals of 2-4 inches, although idealized
training over a particular location has the potential for rainfall
totals over 4 inches in 3 hours. Current thinking is that the
coverage of flash flooding through 10Z will remain low enough to
keep the "flash flooding possible" wording on this message given
dry antecedent conditions, but concerns for rapid rises of water
will exist across portions of the sensitive Hill Country despite
the dry antecedent grounds.

Otto

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

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

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

LAT...LON   32119869 31429791 30329826 29749881 29269946
            28930081 29550147 30710103 31759995