Mesoscale Precipitation Discussion 0424
NWS Weather Prediction Center College Park MD
440 PM EDT Tue Jun 11 2024

Areas affected...South Florida

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

Valid 112040Z - 120240Z

SUMMARY...Slow-moving and locally training showers and
thunderstorms with extreme rainfall rates will continue going into
the evening hours. Flash flooding is ongoing across parts of south
FL and this threat will continue into the evening hours with some
expansion of the threat along the I-95 corridor from Miami to Fort
Lauderdale expected.

DISCUSSION...The late-day GOES-E IR satellite imagery in
conjunction with dual-pol radar imagery shows numerous clusters of
cold-topped convection with extreme rainfall rates impacting south
FL, and especially the I-95 corridor of southeast FL around the
Miami metropolitan area. The convection is focusing along a
southwest/northeast orientation trough axis with a deep tropical
airmass characterized by 2.5+ inch PWs and a tally skinny CAPE
environment with MLCAPE values of 1500 J/kg.

Rainfall rates with the ongoing activity have been extremely high
and as high as 2 to 4 inches/hour with an extremely efficient
environment favored by very high WBZ heights (over 15,000 feet)
and persistent deep layer ascent that is also being supported by a
30 kt southwest low-level jet coming in off the southeast Gulf of
Mexico.

Given the latest satellite and radar trends, and output from the
HRRR guidance, additional rainfall totals across south FL going
through the mid-evening hours may reach 4 to 8 inches, with
isolated storm totals potentially approaching or exceeding 10
inches.

The urban corridor along I-95 from Miami to Fort Lauderdale will
be at risk for locally significant and potentially
life-threatening urban flash flooding given the extremely high
rainfall rates and persistence of these training clusters/bands of
showers and thunderstorms.

Orrison

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

ATTN...RFC...SERFC...NWC...

LAT...LON   27088005 26367985 25717999 25178042 25118067
            25198118 25528136 25748166 25948174 26298109
            26648069 26968045