Windley Key, Florida Weather Forecast Discussion

945
FXUS62 KKEY 130229
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
1029 PM EDT Fri Sep 12 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 1029 PM EDT Fri Sep 12 2025
It has been an interesting afternoon and evening across the Keys
with multiple rounds of convection. The ones of note were a very
strong thunderstorm that developed over the southern mainland near
Homestead. This strong thunderstorm slowly drifted to the east
southeast resulting in a Special Weather Statement for the Upper
Keys from Ocean Reef to North Key Largo. A Special Marine Warning
was also issued for the surrounding nearshore and offshore waters.
Carysfort Reef Light recorded a peak wind gust to 35 knots or 40
mph at 340 pm EDT. MRMS data showed estimated rainfall amounts of
1 to 2 inches across the region with the heaviest in Miami`s area
where potentially 3"+ may have fallen. Then attention turned to
the western waters. A cluster of storms were moving eastward
towards the Lower Keys. As the storms approached Key West and
surrounding nearshore waters, it prompted a Special Marine
Warning for the Key West Harbor and the surrounding waters. The
peak wind gust here at the office was 27 knots or 32 mph and the
Key West Coast Guard station recorded a peak gust to 31 knots or
36 mph. The Key West NOAA observation recorded the strongest winds
with 40 knots or 45 mph at 642 pm. This cell continued
propagating just offshore the Lower Keys before dissipating on
approach to the Middle Keys. Another boundary moving off the
mainland made way for more convection across Florida Bay and the
Middle and Upper Keys in the past couple hours along with more
convection developing across the offshore Gulf waters.
Temperatures along the Island Chain are mostly rain cooled in the
upper 70s to near 80 degrees. Dew points are in the mid 70s.
Marine platforms around the Keys are mostly convectively
contaminated with north to northeast breezes ranging from 4 knots
at Sand Key to near 15 knots for the other platforms, except
Carysfort around 10 knots.
.SHORT TERM FORECAST...
The 00z evening sounding shows that of a post convective
environment. There is a decent dry layer from around 925 mb to
around 600 mb with a shallow inversion present near 925 mb. The
PWAT value came down from this morning being measured at 2.04
inches which is close to the 75th percentile compared to the 90th
percentile like it has been on previous nights. Instability is
also lower than it was this morning with the CAPE value measured
being 818 J/kg. For now, the keys are mostly worked over, however,
we expect things to destabilize with potentially more convection
expected for the first half of the weekend. Since we have multiple
boundaries, a front nearby, ample moisture, and some instability,
we have the necessary ingredients to keep radar active across the
area. Therefore, no changes expected to the ongoing forecast.
&&
.MARINE...
Issued at 1029 PM EDT Fri Sep 12 2025
There are currently no watches, warnings, or advisories in effect
across the Florida Keys coastal waters. From synopsis, a weak
surface trough strung across South Florida and the Keys will shift
southwards into the Straits over the next couple of days as high
pressure expands southward out of the southeastern United States.
The wet pattern will continue with rain chances likely trending
higher due to the migrating trough. Confidence is very low with
respect to the wind forecast. The trough is expected to stall not
too far off to the south and the fresher breezes associated with
the ridge further north should remain just out of our area through
the weekend. As a result, winds in the near term will be light,
often variable. However, showers and thunderstorms will deliver
localized higher winds and seas. Gentle to moderate northeast to
easterly breezes are expected to build in as the high finally is
able to spread down into our area. With that said, uncertainty
remains considerable.
&&
.AVIATION...
(00Z TAFS)
Issued at 1029 PM EDT Fri Sep 12 2025
VFR conditions are expected to persist through the TAF period.
Earlier convection has stabilized the air across the region for
now but we expect this to be short-lived. There continues to be
multiple boundaries throughout the Keys waters with one currently
moving southwest through the offshore Gulf waters. However, due to
the nature of the environment across the Keys, it is difficult to
say when the next round of showers and thunderstorms will occur.
As a result, VCSH was kept out of the TAF for now, except for MTH
where a light shower was expected to move through in the first
couple hours. Other than that, statistical guidance is showing
the risk for some episodic MVFR CIGs overnight into the early
morning Saturday. This was also too uncertain to put a BKN line in
the TAF, but, will be monitored and updated accordingly. Near
surface winds are expected to remain north to northeast between 2
to 8 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  89  77  89  78 /  70  60  70  60
Marathon  89  77  87  78 /  70  70  70  60
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...MJV
Aviation/Nowcasts....MJV
Data Acquisition.....AJP
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NWS KEY Office Area Forecast Discussion