Grassy Key, Florida Weather Forecast Discussion

273
FXUS62 KKEY 200852
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
452 AM EDT Sat Sep 20 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 451 AM EDT Sat Sep 20 2025
The Florida Keys are experiencing a fairly typical late-
September pattern with warm, humid air dominating the area.
Temperatures are currently in the lower 80s with dew points in the
upper 70s making things feel pretty sticky outside. A gentle
northeast breeze is helping take the edge off the humidity, though
it also signals the presence of a slightly drier air mass that
has limited a majority of shower activity overnight into this
morning. KBYX is currently detecting isolated showers just south
of the Dry Tortugas. Today is expected to be similar to conditions
yesterday with mostly sunny skies and light to gentle winds
making for a nice Saturday!
...FORECAST...
Through the weekend, the Keys will remain under the influence of
a broad ridge aloft with weak synoptic forcing. Low-level
northeast to east flow will continue to advect warm, humid air
into the CWA though precipitable water values are expected to
remain somewhat suppressed through Sunday from a relatively drier
airmass overhead compared to the climatological norm. This should
limit shower activity, although isolated pulse-like showers and
thunderstorms can never be ruled out this time of year. With
minimal convective inhibition, any showers that do form could
briefly intensify before collapsing producing a few lightning
strikes and gusty winds.
By early next week, deeper tropical moisture will return back into
the Keys as the ridge axis shifts. Increasing moisture will
enhance instability and allow for more convection to develop. Have
nudged PoPs up to 40% though guidance is suggesting higher which
will be re-evaulated as confidence increases. Towards late week,
drier mid- level air may move in again reducing shower chances
once again. Outside of convection, breezes throughout the week
will remain light to gentle.
&&
.MARINE...
Issued at 451 AM EDT Sat Sep 20 2025
No watches, warnings, or advisories are currently in effect for
the Florida Keys waters. From synopsis, as drier air continues to
push across the Keys and high pressure builds across the Eastern
Seaboard, drier conditions, coupled with light to gentle northeast
to east breezes, are expected through the weekend. This week,
moisture will return, but winds will remain light to gentle.
&&
.AVIATION...
(06Z TAFS)
Issued at 451 AM EDT Sat Sep 20 2025
VFR conditions will prevail at both island terminals today. Latest
guidance shows the terminals remaining dry through the period.
However, we cannot rule out an isolated shower or thunderstorm. Due
to the low confidence in whether or not we get a shower or
thunderstorm, VCSH is not mentioned in the TAF at this time. Near
surface winds will remain northeast to east between 3 to 8 knots.
&&
.CLIMATE...
On this day in 2005, Hurricane Rita passed 45 miles south of Key
West as a category two hurricane. Key West recorded sustained
winds of 62 mph and gusts to 76 mph. Marathon reported sustained
winds of 41 mph and gusts to 52 mph. Flooding 2 feet above ground
level flooded up to 4 blocks inland in midtown Key West. Up to 200
residences affected by storm surge in Key West. Storm tides
estimated at 3 to 5 feet above mean sea level. Numerous coastal
streets flooded with U.S. Highway One flooded at Sea Oats Beach on
Lower Matecumbe Key. Rainfall totaled 4.26 inches at John
Pennekamp State Park in Key Largo.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...AP
Aviation/Nowcasts....MJV
Data Acquisition.....MJV
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NWS KEY Office Area Forecast Discussion