460
AWUS01 KWNH 031728
FFGMPD
FLZ000-032325-

Mesoscale Precipitation Discussion 0157
NWS Weather Prediction Center College Park MD
127 PM EDT Sun May 03 2026

Areas affected...southeastern FL

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

Valid 031726Z - 032325Z

SUMMARY...Thunderstorms are expected to expand in coverage through
the afternoon across southern FL. Storm total rainfall of 2 to 4
inches (locally higher) may occur across isolated sections of the
urban southeastern corridor due to cell mergers and brief upstream
development.

DISCUSSION...17Z surface observations and visible satellite
imagery showed a cold front from just south of FLL to ~20 miles
south of MKY (marked by strengthening northerly winds and dewpoint
falls) with a pre-frontal trough/outflow boundary extending from
south of the Keys to just south of Great Abaco in the Bahamas. The
southern boundary was acting as the effective front with northerly
winds at the surface and cooler surface temperatures, but VAD wind
data indicated that the rain-cooled boundary was only 1-2 kft
deep. 17Z SPC mesoanalysis data indicated that the environment
over southern FL consisted of 500-1500 J/kg MLCAPE (slightly
higher MUCAPE) and PWs near 2 inches (near/above SPC sounding
climatological daily max at MFL)

In addition, effective bulk shear of 40-45 kt was sufficient for
storm organization with the potential for supercells and
multicells. Average cell motions should remain progressive,
following the deeper layer mean wind from the WSW at 20-30 kt, but
organized cells could deviate right of the mean wind. In the upper
levels, the right-entrance region of a strong sub-tropical jet
departing from off of the coast of the Southeast may continue to
provided added support for ascent across southern FL into the
evening hours.

Given the shallow nature of the stable layer at the surface,
breaks in clouds could allow some surface-based cells to form
should sufficient heating through cloud cover occur. Regardless of
where cells are rooted, eastward tracking thunderstorms are
expected to develop and increase in coverage, perhaps quickly, in
the 18-21Z time frame following peak diurnal heating and recent
HRRR/RRFS forecasts. Upstream redevelopment will be possible given
an unstable southerly component to the inflow, with potential for
1-2 inch hourly rainfall and storm totals of 2 to 4 inches
(isolated higher rates/totals possible). Given mostly dry
antecedent conditions across southern FL (with a few exceptions),
any flash flooding that occurs should be isolated and likely urban
in nature.

Otto

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...KEY...MFL...MLB...

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

LAT...LON   27037996 26737974 25997978 25387999 25238015
            25258039 25528053 26458042 26988014