Upper Sugarloaf Key, Florida Weather Forecast Discussion

962
FXUS62 KKEY 110829
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
429 AM EDT Thu Sep 11 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 248 AM EDT Thu Sep 11 2025
A weak surface trough stretches across South Florida and the Gulf
this morning, resulting in light and variable, mostly westerly
breezes across the Keys and surrounding waters. Last evenings
sounding indicated precipitable water is well above normal at 2.3
inches, with ample CAPE and no inhibition. Meanwhile, complicated
troughing aloft reaches southward into the Gulf. As a result, rain
chances will remain above normal. While convective activity near
the island chain is rather limited this our, scattered activity
is picking up off to our west through northwest and southeast.
Uncertainty remains quite high through the duration of the
forecast. Over the next couple of days the troughing over the
eastern United States will amplify, reaching down into the Yucatan
by this weekend. This along with precipitable water remaining
well above 2 inches will result in rain chances remaining above
normal. The highest rain chances are expected in the Friday
through Saturday time frame as this is where the lower level
troughing and confluent flow will best focused near the Keys. In
addition, there is the potential for some upper level support due
to the unusually amplified upper trough just to our west. All
guidance indicates a surface high over the eastern United States
will shove a front southward through South Florida tomorrow and
further into the Straits or Cuba this weekend. With that said, the
stronger winds associated with the high is not expected to make
much headway into the Keys. As a result, winds are expected to
remain light whilst shifting from northwest to north to northeast
sometime this weekend.
The tail of the upper level trough is expected to cut off late
this weekend and ball up over the eastern United States early
next week with associated troughing remaining across the Gulf.
This is expected to help deepen a coastal trough off the Atlantic
Coast and keep weak lower troughing and a moisture rich
atmosphere across South Florida and the Keys. Rain chances will
probably remain above normal in this environment. Winds will be
highly dependent on the evolution of any Atlantic troughing. With
that said, winds should transition to gentle to moderate northeast
to easterlies early next week.
&&
.MARINE...
Issued at 248 AM EDT Thu Sep 11 2025
There is a stunning amount of uncertainty with the marine wind
forecast in the upcoming days. This is initially due to a weak
trough strung across South Florida, resulting in light and
variable winds, likely perturbed by day time heating and
convective influences. Heading into this weekend, high pressure
expanding down the southeastern United States and Florida is
expected to shove a front southwards through South Florida and by
sometime this weekend be located either across the Florida Straits
or Cuba. The belt of stronger breezes around the building high is
expected to remain north of Keys waters and the local pressure
field expected to remain quite relaxed and winds light. It
wouldn`t take much of a shift for a very different outcome. Stay
tuned.
&&
.AVIATION...
(06Z TAFS)
Issued at 248 AM EDT Thu Sep 11 2025
VFR conditions are expected to prevail this morning at EYW and MTH.
While shower and thunderstorm activity will be possible throughout
the TAF period, chances are a bit lower until after sunrise. Opted
to maintain VCSH after this time. Activity before this time and any
shower-driven excursions into sub-VFR will be addressed via
amendments as necessary. Winds will generally be light and variable
through sunrise, then will become predominately westerly though
still light and subject to variability.
&&
.CLIMATE...
On this day in 1900, the daily record cold high temperature of 80F
and the daily record low temperature of 71F were recorded at Key
West. In addition, the daily record rainfall of 3.87" was recorded
at Key West in the same year. Temperature records for Key West date
back to 1872. Rainfall records for Key West date back to 1871.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...11
Aviation/Nowcasts....MC
Data Acquisition.....MC
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NWS KEY Office Area Forecast Discussion