AWUS01 KWNH 221612
FFGMPD
LAZ000-TXZ000-222211-

Mesoscale Precipitation Discussion 0974
NWS Weather Prediction Center College Park MD
1212 PM EDT Fri Aug 22 2025

Areas affected...southeast Texas, southwestern Louisiana

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

Valid 221611Z - 222211Z

Summary...Slow-moving convection continues to expand in coverage
this morning, with areas of 2-3 inch/hr rain rates becoming likely
beneath the strongest storms. Flash flooding is expected.

Discussion...Deep convection has been focused mainly along coastal
areas of Texas and Louisiana for most of the morning. Over the
past hour or so, storms has materialized just inland across the
discussion area (nearer to I-10) due to 1) strong surface heating/destabilization, 2) abundant moisture (2.3 inch PW), and
3) convergence along a weak front across the region (generally
from Houston Metro east to Baton Rouge, LA). Kinematics/steering
flow aloft are very weak (<5 knots), suggestive of slow-moving
cells/clusters that are outflow dominant and propagate erratically
through the afternoon. A few of these clusters were forming near
Lake Charles and just north of Houston while already producing
spots of 1-2 inch/hr rain rates.

With continued surface heating, convective clusters are expected
to expand in coverage. The orientation of storms relative to
outflow from prior activity over the Gulf suggests potential for
several cell mergers as well. 2-3 inch/hr rain rates will
eventually materialize, and may impact populated/flashy urban
centers such as Lake Charles, Beaumont, and Houston through 20Z.
FFGs near those areas are as low as 1-1.5 inches/hr and should be
readily exceeded. Surrounding areas have higher FFGs (in the 3
inch/hr range) that should still be exceeded as stronger
convection develops through the morning and early afternoon.
Areas of flash flooding are expected given the developing scenario.

Cook

ATTN...WFO...CRP...EWX...HGX...LCH...

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

LAT...LON 31019345 30519193 29869179 29589269 29619471
28749616 29029737 29879728 30399670 30939521

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AWUS01 KWNH 301305
FFGMPD
LAZ000-TXZ000-301715-

Mesoscale Precipitation Discussion 1031
NWS Weather Prediction Center College Park MD
904 AM EDT Sat Aug 30 2025

Areas affected...eastern TX into southwestern LA

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

Valid 301303Z - 301715Z

SUMMARY...Heavy to extreme rain rates over 3 in/hr are expected to
occur within localized pockets over portions of eastern TX and
southwestern LA over the next few hours. Areas of flash flooding
are likely to continue through 17Z.

DISCUSSION...1245Z radar imagery over the lower Sabine River
Valley showed a small cluster of thunderstorms west and northwest
of LCH with 3 Wunderground observation stations reporting 3+
inches of rain in an hour two stations showing 5 inches in an hour
through 12Z. Thunderstorm coverage was expanding NNW from
southwestern LA into portions of eastern TX along an elevated
(925-850 mb) convergence axis with low level flow intersecting the
boundary from the west. Some of the "strongest" low level flow was
located just south of the DFW Metroplex and over southwestern LA
with about 10-15 kt oriented nearly perpendicular to the elevated
convergence axis with mean layer winds directing cells slowly
toward the southeast. SPC mesoanalysis data from 12Z showed MUCAPE
values of 500-1500 J/kg coincident with PWATs of 2.1 to 2.3+ inches.

Short term forecasts from the RAP show the low level flow
maintaining over the next few hours but with gradual weakening
through 17Z which may act to disrupt organization late this
morning. However, the environment will remain supportive of highly
efficient rainfall production until then with pockets of extreme
rain rates possible (3+ in/hr) and localized storm totals in
excess of 5 inches through 17Z. Areas of flash flooding will be
likely and trends will be monitored for additional MPDs as needed
later this morning.

Otto
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