AWUS01 KWNH 291301
FFGMPD
MSZ000-LAZ000-TXZ000-291730-

Mesoscale Precipitation Discussion 1023
NWS Weather Prediction Center College Park MD
900 AM EDT Fri Aug 29 2025

Areas affected...eastern TX into LA and southern MS

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

Valid 291259Z - 291730Z

SUMMARY...Localized to widely scattered areas of flash flooding
will remain likely early this morning, possibly extending into the
early afternoon from portions of eastern TX into LA and southern
MS. While coverage of flash flooding may be limited, the potential
for very high rates in excess of 3 in/hr will exist.

DISCUSSION...1240Z radar imagery showed elevated thunderstorms
from northeastern TX into central LA and southern MS with embedded
areas of training and MRMS-derived hourly rainfall of 2 to 3+
inches...mainly over the north-central TX/LA border and just north
of Alexandria, LA. The environment was characterized by very high
moisture (PWATs 2.2 to 2.5 inches) and 500-1000 J/kg MUCAPE via
12Z SPC mesoanalysis data. Rainfall has been efficient given this
environment with local 88D imagery showing cells containing low
echo centroid signatures and 15 minute rates over 1 inch per MRMS
and gauge data. An elevated convergence axis stretched
southeastward from northeastern TX and was being overrun by
925-850 mb winds of ~15 to 20 kt from the SW, favorably ascending
the boundary with deeper layer mean winds translating cells toward
the southeast.

An MCV-like feature appeared to be located between JAN and PIB,
with movement toward the east. The low level convergence axis has
been advancing slowly but steadily toward the south over
southwestern MS into central LA, limiting the coverage and
magnitude of rainfall rates. The boundary was also advancing over
TX, toward the southwest, but its orientation aligning more
favorably with the mean wind was supporting a locally enhanced
flash flood threat over northeastern TX as of 1240Z. This area
will continue to be a locally higher concern in the short term
with hourly rainfall of 2 to 3+ inches. Short term RAP forecasts
show weakening and further veering of the low level flow through
17Z which should tend to lessen the overrunning component from
central LA into MS, but some isolated areas of training will
remain along the elevated convergence axis.

The flash flood threat should linger a bit longer over eastern TX
into western LA where despite weakening low level winds into the
rest of the morning, high moisture and areas of training should
focus at least a localized flash flood concern over the next few
hours. Additional development of thunderstorms with the onset of
daytime heating across southwestern LA may also pose a flash flood
threat after 15Z with an added component related to the advancing
low level axis of convergence from the north.

Otto

ATTN...WFO...FWD...HGX...JAN...LCH...LIX...MOB...SHV...

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

LAT...LON 33179511 33179444 32529362 31919224 31789059
31958945 31708869 31128847 30458876 29768996
29429118 29439301 29719395 30539469 31489541
32179566 32759557

$$
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