Cudjoe Key, Florida Weather Forecast Discussion

190
FXUS62 KKEY 101902
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
302 PM EDT Wed Sep 10 2025
...New AVIATION...
.AVIATION...
(18Z TAFS)
Issued at 303 PM EDT Wed Sep 10 2025
VFR conditions are expected to prevail at both EYW and MTH for the
rest of today and into tonight. Isolated showers with occasional
embedded thunderstorms continue to percolate around either
terminal with VCSH included for as long as this activity is
expected to be around, though short term amendments will be issued
as required. Near surface winds will be light out of the southwest
to west, becoming variable.
&&
.PREVIOUS DISCUSSION...
Issued at 1135 AM EDT Wed Sep 10 2025
Conditions have settled down after a somewhat active start to the
day. Just before sunrise, a few thunderstorms developed just west
of the Lower Keys before moving over the island chain bringing a
quick early morning dousing. MRMS QPE notes max values just under
0.6 inches over land with higher values estimated over waters to
the south. Meanwhile, widely scattered showers and a few
thunderstorms churned east through the north edge of our Deep Gulf
waters. While the island chain is now rain free, convection
continues to bubble in the Gulf waters and also in the Straits
just south of the Lower and Middle Keys. Offshore observation
stations report light broadly southwest to west breezes outside of
convection. Temperatures along the island chain range in the
upper 80s to near 90 with dewpoints in the upper 70s.
No real change in our synoptic pattern keeps rain chances above
normal in the short term. A surface low in the Gulf is promoting
generally southwest breezes through our area. Meanwhile, confluent
and moist flow in the low to mid levels will keep a decent
environment for developing convection today, but only if lift can
be found from existing boundaries. This morning`s KKEY balloon
sounding is juiced up with a PW near 2.5 inches. While part of
this may be due to the showers nearby at time of launch, CIMSS
MIMIC PW does note a large swath of values greater than 2.25
inches painted across the island chain. Now whether or not showers
will get to use this moisture is a different story as CAMs are
back and forth on if convection will explode or not. A hint of dry
air in the eastern Straits could spell some trouble if it
eventually makes its way around. Opted to keep 50 PoPs today
moving to 40% tonight keeping just above guidance while still
respecting the possible intrusion of dry air and lack of lift.
Tomorrow, light and variable winds could inspire an island cloud
line day, so be on the lookout for that.
&&
.FORECAST...
Issued at 430 AM EDT Wed Sep 10 2025
The previously mentioned Gulf surface low is expected to degrade
into a long trough straddling the Florida Peninsula today into
tonight. As a result, light to gentle southwesterly breezes are
expected to slacken further, becoming variable at times. Forecast
soundings suggest some drier air associated with a dying ridge to
our southeast will percolate into our area. This should allow for
somewhat lower rain chances over the next couple of days. Expect
near to slightly above normal temperatures with dew points
stagnant in the mid to upper 70s.
Confidence is slowly increasing that high pressure over the
eastern United States will expand southward late in the week,
moving into South Florida late in the week and possibly the Keys
this weekend. This will likely result in a modest strengthening of
broadly northeasterly breezes, with the stronger winds remaining
further north of our area. This will unfold as a mid latitude
trough amplifies, reaching deep into the Gulf. The amplifying
trough aloft should encourage the formation of surface through
lower level troughing off the southeast Coast. Should this occur,
it will assist in driving a long stalled boundary southward into
or past the Keys this weekend. Uncertainty remains high regarding
timing, position, and strength of any of these features. The
combination the lower level boundary, likely some upper level
support, and the associated increase in deep layered moisture
should bring about a period or two of considerably higher rain
chances. For now will maintain likely PoPs in the Friday night
through Saturday night time frame. Currently, not much in the way
of airmass change is expected with guidance suggesting dew points
may only briefly dip into the lower 70s, not very exciting.
&&
.MARINE...
Issued at 1135 AM EDT Wed Sep 10 2025
No watches, warnings, or advisories are currently in effect for
the coastal waters of the Florida Keys. From synopsis, a weak
surface low centered over the eastern Gulf will smear out into a
flimsy trough stretching across the Florida Peninsula. In
response, light southwesterly breezes will become more variable in
direction. Disorganized weak flow will remain through much of the
remainder of the work week. While uncertainty remains high,
confidence is ticking upward that high pressure over the eastern
United States will manage to build southward through Florida and
into the Keys this weekend. This will spur modestly strengthening
northeasterlies.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  81  90  80  90 /  30  40  40  50
Marathon  81  90  80  89 /  40  50  40  60
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...JAM
Aviation/Nowcasts....JAM
Data Acquisition.....JAM
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NWS KEY Office Area Forecast Discussion