Special Weather Statement, NWS Miami, FL

Area Forecast Discussion
National Weather Service Miami FL
421 PM EDT Thu Aug 15 2019

...FLOOD WATCH EXTENDED THROUGH FRIDAY EVENING FOR EAST COAST
METRO AREAS...

...SOME STRONG TO EVEN ISOLATED SEVERE STORMS POSSIBLE EARLY THIS
EVENING AND AGAIN ON FRIDAY...

.DISCUSSION...

THIS AFTERNOON THROUGH FRIDAY...
The mid to upper level trough over the Southeastern United States
will remain nearly stationary through Friday, as high pressure
remains nearly stationary over the Central Atlantic waters. At the
same time, a weak cold front over the Southeastern United States
will move slowly south into Northern Florida. This will keep the
steering flow in a south/southwest direction over South Florida
through Friday keeping the deep tropical moisture in place along
with the PWAT values around 2 inches which is in the 90th
percentile for this time of year.

Showers and thunderstorms will continue to develop over the
interior areas and push slowly east into the east coast metro
areas through rest of the afternoon hours before slowly
dissipating this evening. The weather should then be mostly quiet
for the overnight hours tonight before another round of showers
and thunderstorms develops on Friday over the region. The best
coverage of the showers and thunderstorms will be over the
interior and east coast metro areas on Friday afternoon where the
sea breezes collide. Therefore, heavy rainfall is still possible
this afternoon into early this evening and again Friday afternoon
especially over the interior and east coast metro areas. More
information on the potential of flooding conditions for the east
coast metro areas is available in the hydro section below.

The 500 mb temps have cooled to -6C this morning in the MFL
sounding, and the short range models are showing the 500 mb temps
to continue to cool down to -7 to -8C on Friday, as a mid to
upper level low will be located over the Bahamas. This will allow
for some of the storms this afternoon and again on Friday to
become strong with even a possible severe storm possible especially
over the interior and east coast metro areas where the sea
breezes collide. The primary impacts from the strong to severe
storms will be gusty winds up to 50 mph and small hail along with
frequent lightning strikes.

THIS WEEKEND...
The mid to upper level trough is forecast by the short range
models to move east this weekend, allowing for the ridge of high
pressure over the Central United States to build westward into the
Florida peninsula. This will allow for the steering flow to become
more south/southeast this weekend and focus the best coverage of
showers and thunderstorms over the interior and Lake Okeechobee
region. The PoPs will be a little bit higher on Saturday than
Sunday, as some drier air will be working into the region on
Sunday ahead of a tropical wave that is currently approaching the
Leeward and Windward Islands.

EXTENDED FORECAST...

The tropical wave is forecast by the long range models to move
west northwest through the Northwest Caribbean Sea early next week
and into the Southern Gulf of Mexico waters by middle of next
week. The northern portion of the wave is forecast to move through
South Florida early next week bringing in another around of PWAT
values around 2 inches leading to scattered to numerous showers
and thunderstorms over the region along with some heavy rainfall.
The weather will then get back to more of a typical summer like
pattern over South Florida for the middle of next week, as the
ridge of high pressure remains over the Western Atlantic waters
extending back west into the Florida Peninsula. This will focus
the shower and thunderstorm activity east coast areas in the late
night and morning time shifting to the interior and west coast
metro areas in the afternoon and evening hours for the middle of
next week.

&&

.MARINE...
The winds will remain south/southwest tonight through Friday night
at 10 knots or less. The winds will then swing to more of a
south/southeast direction this weekend with speeds still at 10
knots or less, before going more easterly early to middle of next
week with speeds increasing to 10 to 15 knots. This will keep the
seas at 2 feet or less in both the Atlantic and Gulf waters
through this weekend, before increasing to 2 to 3 feet in the
Atlantic waters early next week.

&&

.HYDROLOGY...
Rainfall amounts across South Florida range from 2 to 4 inches
over the western areas along the Gulf coast to 3 to 5 inches with
isolated amounts up to 7 inches over the eastern areas of South
Florida during the last 7 days. This has allowed for the ground
over the eastern areas to become saturated. Any additional
rainfall amounts this afternoon (east coast: additional 0.5 to 1.1
inches) and again on Friday afternoon (east coast: another 0.25
to 0.5 inches) will lead to possible flooding conditions over the
east coast metro areas. Therefore, the Flood Watch has been
extended for the east coast metro areas through Friday evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  90  77  92  77 /  70  60  80  60
Fort Lauderdale  90  81  92  79 /  60  50  70  60
Miami            90  79  93  79 /  60  40  70  50
Naples           89  78  90  77 /  40  20  30  20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch until 8 PM EDT this evening for FLZ068-072-074-168-
     172-173.

AM...None.
GM...None.

&&

DISCUSSION...54/BNB
MARINE...54/BNB
HYDROLOGY...54/BNB