Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 122333
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
733 PM EDT Wed Aug 12 2020

.Aviation (00Z TAFs)...

Showers and storms are waning but isolated convection remains
possible this evening, especially around/south of APF.
Shower/storm chances increase Thursday morning for the eastern
terminals before the focus shifts inland and towards the Gulf
Coast. Naples is likely to see thunderstorms on station once again
after 18z. Light and variable winds overnight shift ESE-SE
Thursday afternoon except at Naples where winds become more WSW
with the Gulf Breeze.

&&

.Update...

Shower and thunderstorm coverage is waning and decreased PoPs
area-wide as a result. That said, still enough CAPE around to
kick off a few more storms in areas not yet contaminated with
cloud debris. This is evident currently across southern portions
of Collier County and over the adjacent waters. Shower coverage
should become more isolated overnight and mainly confined to the
local waters. Thereafter shower/storm coverage increases for the
east coast around 13-15z before the Atlantic breeze pushes inland
and shifts the afternoon focus over the interior and Gulf Coast
areas.

&&

.Prev Discussion... /issued 318 PM EDT Wed Aug 12 2020/

Short Term (Rest Of Today And Thursday)...

A weak mid-level trough is currently located over Florida, situated
between a high pressure system in the central Gulf of Mexico and the
Bermuda ridge axis. Relatively light easterly flow persists under
these synoptic conditions. Convection from this morning along the
Broward/Palm Beach County border has disrupted the Atlantic sea-
breeze formation. As a result most of the activity has ceased along
the Atlantic metro region, though isolated to scattered showers are
still present over the Atlantic coastal waters.

The aforementioned easterly flow is forcing westward propagation of
an outflow boundary over the western interior to converge with the
Gulf Coast sea-breeze. Consequently, showers and thunderstorms are
developing over metro Collier County. This appears to be the area
most favorable for convective development over the course of the
afternoon, although strong storms may develop over the interior
where sufficient low-level convergence and mixing become
superimposed. The 12Z MFL sounding, southerly winds within the 850-
600 hPa layer has advected higher PW values (2.13 ins) over the CWA.
While this may contribute to higher instability (CAPE) over the
region, this is offset modest lapse rates around -6 C/km within this
layer. While there could be a few stronger storms with gusty winds
and small hail, the main concern will be heavy localized rainfall
leading to potential flooding concerns.

For Thursday, the overall synoptic pattern will remain the same
with the showers and thunderstorms over the Atlantic and east
coast in the morning hours before activity shifts to be over the
interior and Gulf Coast. High temps will be in the low to mid 90s
once again.

Long Term (Friday Into Next Week)...

Not much changes in the flow pattern across South Florida the
remainder of the week into the weekend. A trough sinks into the
Southeast remaining north of the region with the Atlantic ridge
keeping light east to southeasterly flow across the area. This will
continue to allow for the typical diurnal summertime pattern with
showers and storms over the Atlantic and east coast in the morning
and early afternoon, before sea breezes develop and convection
shifts over the interior and west coast in the afternoon and
evening. Main concern will continue to be locally heavy rainfall
with light flow and slow storm motion with high rainfall rates.
Isolated stronger storms are possible that may be capable of
producing an isolated gusty downburst.

As we move into Sunday and into next week the flow regime will be
come more southerly, maybe even southwesterly which under this flow
region afternoon showers and thunderstorms will focus over northern
portions of the area around Lake Okeechobee and Palm Beach region.

Temperatures will remain hot in the low to mid 90s with heat
indices reaching into the triple digits each afternoon. Heat
indices up to 105 are possible within areas that do not get the
sea breeze or convection, particularly over the interior.

Marine...
High pressure across the region will continue to maintain
light east to southeasterly wind flow and generally favorable marine
conditions throughout the forecast period. Isolated to scattered
showers and storms will be possible across the Atlantic waters
during the overnight and morning hours, becoming focused across the
Gulf waters during the afternoon and early evening hours.

Aviation...
A weak upper level trough and Bermuda high, have allowed for a
weak flow over the area, as well as enough instability to cause
convection to initialize this morning, and isolated TS moved
across South Florida. This cause abundant cloud cover and has
hindered convection this afternoon. However, as the sky clears,
daytime heating should allow for another round of TSRA to develop,
mainly in the interior and Gulf coast. There are a few isolated
TSRA over the Atlantic, which may move onshore this afternoon.
&&

.Preliminary Point Temps/PoPs...
West Palm Beach  78  91  78  91 /  20  30  10  40
Fort Lauderdale  80  90  80  90 /  20  30  10  40
Miami            80  92  79  91 /  30  30  10  40
Naples           76  93  76  93 /  20  60  30  50

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&

Update/Aviation...34/SPM
Short Term...09/Bhatti
Long Term...33/Kelly


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