From Weather Alert@21:1/175 to All on Tue Feb 16 23:36:00 2021
AWUS01 KWNH 161846
FFGMPD
FLZ000-162344-
Mesoscale Precipitation Discussion 0023
NWS Weather Prediction Center College Park MD
145 PM EST Tue Feb 16 2021
Areas affected...Southeast Florida Coast
Concerning...Heavy rainfall...Flash flooding possible
Valid 161844Z - 162344Z
Summary...A few rounds of thunderstorms producing locally heavy
rainfall are expected through the afternoon. Isolated hourly
totals approaching 1.5-2.0 inches could result in localized flash
flooding, particularly for sensitive urban areas.
Discussion...Along and ahead of a cold front that is inching
eastward, the environment early this afternoon is characterized by
SBCAPE of 2000 J/kg despite some cloud cover seen in recent
satellite imagery. An axis of higher moisture exists as well with
the latest PWs ranging from 1.7 to 1.9 inches, which is about 2
standard deviations above the normal. Radar and observations show
a few lines of storms moving through with recent reports of
locally 1 to 1.5" have fallen in and around Miami.
The moderately unstable environment ahead of the front will be
sufficient for scattered thunderstorms to continue to develop and
track east/northeast through the afternoon. The approach of the
front itself and the upper level wave/troughing well to the north
will provide the larger scale forcing in addition. The 850-300 mb
wind layer is southwesterly and parallel to the expected storm
motions, thus repeating rounds and training are likely.
The most recent hi-res guidance supports some isolated hourly
totals up to 2" and some totals through 00Z of 2-4" with localized
5" totals possible. The 12Z HREF indicates high probabilities of
exceeding 1" while showing a slight signal for 2"+/hr totals.
Despite recent drier than normal conditions, the repeating rounds
over a sensitive urban location could result in some
localized/isolated flash flood instances through early this
evening.