Duck Key, Florida Weather Forecast Discussion

196
FXUS62 KKEY 291819
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
219 PM EDT Mon Sep 29 2025
...New AVIATION...
.AVIATION...
(18Z TAFS)
Issued at 220 PM EDT Mon Sep 29 2025
VFR conditions will prevail at both EYW and MTH for the rest of
today and into tonight. Low rain chances will leave mention out of
both TAFs. Near surface winds will be out of the northwest at near
10 knots with occasional to frequent gusts of 15 to 20 knots.
&&
.PREVIOUS DISCUSSION...
Issued at 1130 AM EDT Mon Sep 29 2025
A warm and dry day is underway across the Florida Keys as Tropical
Storm Imelda spins just off the east coast of mainland Florida. As
expected, our area finds itself in the dry slot of Imelda with
only a couple broken lines of fair weather cumulus streaking
across the island chain on GOES-19 visible imagery. KBYX radar
is free of precipitable echoes in our area but does catch some of
Imelda`s outermost rain bands to the northeast. These bands had
been drifting along the side of our easternmost waters earlier
this morning, but have since trekked north following the storm`s
expected path. Meanwhile, moderate to fresh northwest to north
breezes are observed along our offshore observation stations with
the higher magnitudes unsurprisingly found in the northeast
portion of our area closer to Imelda. Mostly clear skies are
resulting in temperatures once again reaching the mid to upper 80s
across the Keys despite a northerly wind direction.
Imelda`s influence on our sensible weather continues to be limited
to our winds. Despite its eventual easterly turn into the
Atlantic towards Hurricane Humberto, Imelda`s wind field is
expected to expand along its path keeping conditions breezy at
times for the Keys in the short term. These northwesterly breezes
will continue to draw dry modified continental air into our area.
This morning`s KKEY 12z sounding is notably drier than 24 hours
ago with a drop in PWAT greater than 0.3 inches. Dry air layers
now start just above 800 mb and is already acting to keep
organized convective development at bay despite a cyclonic surface
wind field and accelerated flow. Thus slight chance PoPs continue
to look appropriate for the short term. The biggest forecast
question continues to be when the winds will peak again with
numerical guidance pointing to later today into the evening and overnight
hours. A thermal low developing on mainland Florida with these
mostly clear skies may help speed up this change however. Will
continue to evaluate and update the forecast with new information
as needed, stay tuned...
&&
.FORECAST...
Issued at 400 AM EDT Mon Sep 29 2025
Ensemble numerical weather prediction guidance is in marked
agreement regarding the evolution of Imelda over the next couple
of days, with the system drifting northward as it strengthens near
the Bahamas through Tuesday morning. As it comes in closer
proximity to much stronger Humberto, the system will sharply be
dragged eastward and (thankfully) away from the Southeast. Despite
the movement away from the Southeast and the Keys, the National
Hurricane Center is forecasting a largely expanding wind field
associated with Imelda over the next several days, which will keep
conditions breezy at times through at least early Tuesday night.
The northwesterly flow on the backside of Imelda will also
continue to usher in much drier conditions for the Keys. Slight
measurable rain chances thus seem appropriate for today through
Tuesday.
With Imelda and Humberto moving away by mid-week, high pressure
over the Eastern Seaboard will slide slowly eastward into the
western North Atlantic. Winds will respond, clocking around to the
north to northeast, then eventually northeast to east by the end
of the week. A return to seasonably wet and thundery conditions is
expected as well for the extended forecast period.
&&
.MARINE...
Issued at 1130 AM EDT Mon Sep 29 2025
A Small Craft Advisory is in effect for the easternmost Straits of
Florida and Small Craft Should Exercise Caution for increasing
winds in all other Keys coastal waters. From synopsis, Tropical
Storm Imelda, located in the vicinity of the Bahamas, will move
slowly northward today and tonight, then make a sharp eastward
turn on Tuesday into the west- central North Atlantic. Moderate to
fresh northwesterly breezes today through Tuesday will slacken by
Tuesday night. High pressure over the Eastern Seaboard will
slowly slide eastward into the western North Atlantic, with mainly
gentle northwesterly breezes eventually veering to the northeast
to east for the middle to latter part of the work week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  80  91  78  89 /  20  20  30  30
Marathon  80  90  78  88 /  20  20  30  30
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory until 5 AM EDT Tuesday for GMZ052-072.
&&
$$
Public/Marine/Fire...JAM
Aviation/Nowcasts....JAM
Data Acquisition.....JAM
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NWS KEY Office Area Forecast Discussion