AWUS01 KWNH 221701
FFGMPD
ALZ000-MSZ000-LAZ000-222259-

Mesoscale Precipitation Discussion 0975
NWS Weather Prediction Center College Park MD
100 PM EDT Fri Aug 22 2025

Areas affected...southeastern Louisiana, coastal areas of
Mississippi, far southern Alabama

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

Valid 221659Z - 222259Z

Summary...Spotty/isolated flash flood potential exists with
slow-moving thunderstorms across the discussion area through 22Z/4p CDT.

Discussion...Recent satellite imagery indicates deepening
convection along a variety of subtle low-level confluence
boundaries across the discussion area. Surface heating across the
region has enabled development of 4000 J/kg SBCAPE in the
pre-convective airmass amid 2.2 inch PW values. Deep, efficient
convective process are already supporting spots of 1 inch/hr rain
rates (estimated per MRMS). Additional areas of 1-2 inch/hr rain
rates should develop through the afternoon as additional cells
develop and mergers begin to occur.

The rainfall will occur on locally sensitive areas due to
urbanized/hydrophobic surfaces in/near New Orleans, Baton Rouge,
and Northshore Lake Pontchartrain near Covington and Slidell.
Isolated instances of flash flooding will become more probable
during the afternoon hours.

Much of the convective (and flash flood) threat will be diurnally
driven today, although the degree of convective overturning will
ultimately modulate the spatiotemporal threat of the flash flood
risk through 22Z/4p CDT. Eventually, widespread low-level
stabilization should result in a lower flash flood threat,
although this scenario should take a few hours to play out.

Cook

ATTN...WFO...LCH...LIX...MOB...

ATTN...RFC...ALR...ORN...NWC...

LAT...LON 30989045 30788866 30468810 29618895 29148912
28969035 29399160 29889234 30659225

$$
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