365
AWUS01 KWNH 041521
FFGMPD
FLZ000-042115-

Mesoscale Precipitation Discussion 0315
NWS Weather Prediction Center College Park MD
1120 AM EDT Thu Jun 04 2026

Areas affected...southeastern FL

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

Valid 041519Z - 042115Z

SUMMARY...There will be the potential for flash flooding across
mainly the urban corridor of southeastern FL through 21Z.
Localized slow moving showers and thunderstorms will be capable of
producing 2 to 3+ inches of rain in an hour but with 1+ inches in
15 minutes.

DISCUSSION...Visible satellite imagery at 15Z showed a few narrow
streamers of low level convergence into southeastern FL with two
located over Biscayne Bay becoming more active with shower
development over the past hour. While a cold/stationary front was
analyzed south of the Keys at 15Z, it was shallow, with deep
moisture of ~2.0 to 2.2 inches as far north as Broward County.
MLCAPE was estimated via 15Z SPC mesoanalysis data to range from
500-1500 J/kg over Miami-Dade and Broward counties with little to
no CIN. ENE winds of 10-15 kt in the surface to 0-1 km layer. as
seen in VAD wind data from KAMX and RAP analysis soundings over
southeastern FL, shifted to largely light and variable from about
1 km AGL to 8 km AGL, resulting in a mean steering flow of ~5 kt
or less over the region.

Expectations are for additional shower/thunderstorm development
into the afternoon, but with model forecasts showing some
semblance of low level drying in the 18-00Z time frame from the
north, the threat for heavy rain is likely to wane toward 00Z.
While any additional cells that form through the afternoon should
remain disorganized due to a lack of shear, they should also be
slow moving, contingent upon the south/north shifting of the low
level axes of convergence.

Recognizing the environment in place, slow movement will allow for
efficient rainfall production and heavy rain of 1+ inches in 15
minutes along with 2 to 3+ inches per hour. These higher rates are
likely to remain isolated in nature but should they overlap with
the urban corridor of Broward and Miami-Dade counties, rapid
runoff is expected to lead to flash flooding.

Otto

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

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

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

LAT...LON   26377999 25557990 25228027 25208060 25388076
            26278060