Mesoscale Precipitation Discussion 1235
NWS Weather Prediction Center College Park MD
518 AM EST Thu Nov 20 2025

Areas affected...portions of central TX

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

Valid 201015Z - 201600Z

Summary...Another round of heavy rain with flash flood potential
appears to be organizing across western portions of the Edwards
Plateau. Areas of training are likely to produce hourly rainfall
of 1 to 2 inches and 3-hr totals of 2-4 inches (locally higher)
across portions of central TX. A few instances of flash flooding
will be likely through 16Z.

Discussion...Between 09-10Z, thunderstorm coverage has been
increasing across western portions of the Edwards Plateau, from
near SJT, south-southwest toward the Rio Grande. This recent
increase could be related to increasing ascent ahead of an
approaching mid-level trough over AZ and northwestern Mexico,
which was beginning to acquire a negative tilt, but was still
located a bit west of the region. In addition, 925-850 mb winds
remained in the 20-30 kt range from the S to SSE, continuing to
transport anomalous low level moisture northward from the western
Gulf into central TX where 500-1500 J/kg MLCAPE was estimated by
the 09Z SPC mesoanalysis page. Orographic lift across the Edwards
Plateau and a recent increase of low level convergence are also
contributing factors to the recent expansion of thunderstorms.

Recent RAP guidance indicates an axis or axes of low level
convergence aligning from Val Verde County toward the vicinity of
San Angelo through 16Z, matching the orientation of the mean
steering flow from the SSW. This signal, when combined with weak
right-entrance region divergence tied to an upper level jet east
of the upper level trough, is expected to result in areas of
training with 1 to 2 inches of rain per hour, and 2 to 4 inches of
rain in 3 hours or less time (locally higher possible). In
addition, recent WoFS guidance has been increasing probabilities
for 2+ inches of rain from near Val Verde County, north to
northeastward to just southeast of San Angelo over the next few
hours, with the 09Z cycle displaying a 40-70 percent probability
of exceeding 2 inches through 15Z across this corridor. The
anomalously moist environment will support locally high rainfall
intensities which should overcome dry antecedent conditions,
supporting at least a localized flash flood concern over the next
3-6 hours, with locally considerable impacts possible across any
urban/impervious surfaces.

Otto

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

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

LAT...LON   32389946 32119884 31699846 30639852 29619945
            28910033 29010170 30760171 32090080