Sugarloaf, Florida Weather Forecast Discussion

758
FXUS62 KKEY 260821
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
421 AM EDT Fri Sep 26 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 414 AM EDT Fri Sep 26 2025
Conditions across the Florida Keys are still warm and muggy this
Friday morning. GOES East infrared satellite observations detected
lingering high altitude cirrus clouds and some low altitude
cumulus. KBYX and KAMX radar scans highlighted a line of showers
stretching from east of Fort Lauderdale to Floyd`s Wall in the
Florida Straits. Winds across the reef and the island chain
continue to be variable near about 5 knots. It is not a surprise
it feels extremely muggy, the lack of a breeze means moisture
remains trapped near the surface, and the evening 00Z sounding
sampled an environmental precipitable water value above the daily
75th percentile. Preparations for the day will remain the same as
earlier in the week, make sure to stay hydrated, stay in the shade
when possible, and wear sunscreen.
Currently, the weather pattern across the Keys is not too
complicated. The pressure gradient has been pretty weak across the
Gulf for most of the week. Weather phenomena have been driven by
a mixture of sea breezes, cloud lines, weak convergence
boundaries, and outflow boundaries. That comparative lack of
complexity is about to come to a very abrupt end. Tropical Storm
Humberto, which will not pose a threat to the Florida Keys, is
developing and expanding. A tropical wave over Hispaniola,
designated Invest AL94, is progged to continue northwest towards
the Bahamas. North and west of the Keys, a cold front is taking
shape over the central Gulf, which is attached to an upper level
trough digging south into the lower CONUS.
We are staring at the developing interaction between two tropical
lows in the western Atlantic and an eastward moving mid latitude trough
over the eastern CONUS. The environment east of the Keys is about
to become so chaotic it explains why numerical weather models
crunch more numbers than simulations of merging black holes.
Forecast specifics will become more clear with time, and high
confidence exists for a few topics. Breezes are forecast to back
northeasterly tonight and become northwesterly by Sunday night.
Wind speeds from gentle to fresh breezes are possible, though
moderate breezes over water are more likely. Shower coverage is
difficult, because as AL94 develops it will pull environmental
moisture towards its center. The mid latitude trough will also
direct drier continental air into the Gulf towards the Florida
Keys and inhibit shower formation late this weekend to the start
of next week. Statistical model guidance suggests shower chances
as low as 10 to 20% are possible this weekend. The forecast
package was put together while trying to find a middle ground
in the guidance. Showers are most likely Saturday night to Sunday
when the tropical wave is closest to the Florida Peninsula, but
before continental air reaches the Keys. Breezes may peak as early
as Sunday night, but probabilistic guidance suggests Monday to
Monday night as the most likely timeframe. Either way, please
check later updates for more information.
Conditions for the extended forecast are not at all certain. While
we can state winds will be westerly with high confidence, the
magnitude depends on what happens with AL94. Shower coverage is
also highly variable and depends on how long continental air is
funneled towards the Keys. It should be a bit cooler, and any
reprieve to dew points would be appreciated. Regardless of what
happens, the weekend is going to be busy.
&&
.MARINE...
Issued at 414 AM EDT Fri Sep 26 2025
No watches, warnings or advisories are in effect for the Florida
Keys waters. From synopsis, 6ight and variable breezes will
persist through Friday night while the pressure gradient remains
weak. On Saturday, a weak tropical wave, currently located over
Hispaniola, is forecast to move northwest towards the Bahamas.
Meanwhile, an upper level trough over the eastern CONUS will move
close enough to steer the developing low and support its
development east of the Florida Keys. Impacts for the Florida Keys
are expected to be moderate northwesterly breezes and
northeasterly swells along the Upper Keys.
&&
.AVIATION...
(06Z TAFS)
Issued at 414 AM EDT Fri Sep 26 2025
VFR conditions will prevail at EYW and MTH through the 06Z TAF
period. Latest radar imagery shows some showers over the Straits
of Florida. This activity is moving very slowly to the west
northwest. VCSH is not included in the TAF at this time due to
uncertainty on if this activity holds together, or if new shower
development occurs closer. Also, a cloud line is possible later
today. Near surface winds will largely remain light and variable.
&&
.CLIMATE...
On this day in Keys Weather History in 1920, the daily record cold
high temperature of 78F was recorded. This is also tied for the
coldest high temperature ever recorded in September. Temperature
records for Key West date back to 1872.
OF NOTE
In 2005, the last products were issued from WFO Key West at
the airport, and the move to the new office facility began.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  90  80  89  79 /  10  10  10  30
Marathon  89  80  89  79 /  20  20  20  30
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...AJP
Aviation/Nowcasts....MJV
Data Acquisition.....MJV
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest

NWS KEY Office Area Forecast Discussion