AWUS01 KWNH 261258
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-261856-

Mesoscale Precipitation Discussion 1215
NWS Weather Prediction Center College Park MD
857 AM EDT Sun Oct 26 2025

Areas affected...Central Gulf Coast

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

Valid 261256Z - 261856Z

SUMMARY...Isolated to scattered flash flooding will remain
possible through the morning and into the early afternoon across
portions of the central Gulf Coast as convection slowly moves
eastward.

DISCUSSION...Recent radar imagery shows areas of heavy rainfall
continuing to move eastward across portions of southeast LA and
southern MS this morning. IR imagery indicates colder cloud tops
are being maintained, and GLM shows plenty of lightning activity.
This convection is being supported by strong synoptic ascent ahead
of a closed mid level low and within a strongly divergent region
of the upper level flow. Meanwhile, 30 to 40 kts of low level
south to south southeasterly flow is producing strong moisture
transport and convergence. The better instability is confined
closer to the coast, suggesting the highest rainfall rates should
be across southeast LA into far southern MS. However some of the
stronger low level convergence is farther north, which should help
compensate for the lower instability and drive some localized
higher rainfall rates here as well. The convection will continue
to progress off to the east, limiting the duration of highest
rates. However, some brief backbuilding/training of cells into the
strong low level inflow will continue to support some areas of
more persistent rainfall rates. Hourly rainfall should continue to
locally get into the 2-3" range.

Recent HRRR runs continue to indicate 1-3" of rain within the MPD
area, with localized totals over 3". Recent RRFS runs are a bit
higher, showing localized max values over 5" through 19z. Overall
think a compromise of the two is most likely, with localized
rainfall amounts getting into the 3-5" range through 19z where
some brief backbuilding is able to locally extend the duration of
higher rates. Will also note that the HRRR is probably a bit slow
with the eastward progression of the convection, with the RRFS
probably better with the idea of heavier rainfall totals getting
into coastal AL by later this morning.

FFG is quite high across this area, generally 3" in one hour and
4" in 3 hours. It seems unlikely this will get exceeded on a
widespread basis, however where some brief training can occur we
should be able to continue to locally exceed these amounts. Thus
an isolated to scattered flash flood risk is likely to continue,
with an emphasis on urban areas where runoff is enhanced.

Chenard

ATTN...WFO...JAN...LIX...MOB...

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

LAT...LON   31838994 31688862 31408795 30418726 29388857 
            28908922 28918978 29279039 30039039 30549035 
            30829040 31299048 

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