Mesoscale Precipitation Discussion 0429
NWS Weather Prediction Center College Park MD
525 PM EDT Wed Jun 12 2024

Areas affected...South Florida

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

Valid 122125Z - 130325Z

SUMMARY...Catastrophic and life-threatening flash flooding is
expected to continue into the evening hours across south Florida
with an emphasis on the highly urbanized and densely populated
I-95 corridor from Fort Lauderdale south through Miami and
Homestead.

DISCUSSION...An extremely high-impact flash flood event is ongoing
across south Florida with a particular focus on the highly
urbanized I-95 corridor of southeast Florida involving Broward and
Miami-Dade County, with also significant flooding concerns noted
farther west back into parts of Collier and Monroe County where
there continues to an elongated west-southwest to east-northeast
band of very strong convection with extremely high and
life-threatening rainfall rates.

Dual-pol radar in conjunction with local gauges continue to show
rainfall rates reaching well into 3 to 5 inch/hour range, and
while the higher end of these rates has tended to be over the
Everglades over the last few hours, these extreme rates have been
continuing to train over the same area and have also been
advancing through the densely populated and highly sensitive urban
corridor from Fort Lauderdale south down through Miami.

GOES-E IR satellite imagery shows very cold convective tops
persisting with this training band of convection with multiple
overshooting tops reaching on the order of -75 to -80C. An
elongated axis of very strong moisture convergence working in
tandem with deep tropical moisture and instability is expected to
maintain extreme rainfall rates potential over the next few hours.

PWs are locally over 2.5 inches with MLCAPE values of 2000 to 3000
J/kg are seen pooled up over far south Florida. However, there is
also 30 to 40+ kts of effective bulk shear in place, and the
combination of all of these ingredients suggests a persistence to
the well-organized nature of the convective band.

Gradually a southeastward advance of the convection, albeit slow,
is expected over the next few hours. Unfortunately, this means a
persistence of extreme rainfall rates over the highly urbanized
areas of southeast Florida. Widespread flash flooding, with
catastrophic impacts are ongoing from near Fort Lauderdale down
through Hollywood, but the situation is expected to worsen for
areas farther south involving Miami and eventually even Homestead
farther down the I-95 corridor.

An additional 4 to 8 inches of rain with isolated 10+ inch amounts
will be possible going through the early to mid-evening hours. For
some locations, this will bring multi-day storm totals upwards of
15 to 20+ inches. Significant and life-threatening flash flooding
is ongoing and is expected to continue as a result over the next
several hours.

Orrison

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

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

LAT...LON   26438020 26167981 25358018 25108088 25548140
            25828183 25898181 26058123 26238069