Conch Key, Florida Weather Forecast Discussion

680
FXUS62 KKEY 111847
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
247 PM EDT Thu Sep 11 2025
...New AVIATION...
.AVIATION...
(18Z TAFS)
Issued at 247 PM EDT Thu Sep 11 2025
VFR conditions are expected to prevail at EYW and MTH for the rest
of today and into tonight. While conditions have been drier than
expected, precipitation on mainland and in the Deep Gulf is
trudging south towards our waters. Have removed VCSH for the time
being, but short term amendments will be used as short term
impacts become apparent. Near surface winds will be light and
variable, becoming west to northwest.
&&
.PREVIOUS DISCUSSION...
Issued at 1135 AM EDT Thu Sep 11 2025
Skies over the Florida Keys are clearer than they were yesterday
around this time. GOES-19 visible imagery notes mainly fair
weather cumulus dotted around our area outlining residual outflow
boundaries from now diminished nocturnal convection. A glance at
KBYX radar confirms that only a couple small showers between the
Deep Gulf and Straits of Florida remain after widely scattered
showers and some embedded thunderstorms popped up earlier this
morning. The previously mentioned outflow boundaries generally
have free reign to move as they please since light westerly
breezes, that are occasionally variable, are clocking in along
our Reef observation stations. Surface temperatures on land are
unsurprisingly already in the upper 80s with dewpoints persisting
in the upper 70s.
The short term forecast is a touch closer to a normal wet season
day than the last few. Light and almost variable winds combined
with another PW over the 90th percentile measured in this
morning`s KKEY sounding will keep possible cloud line formation on
the table for this afternoon. Meanwhile, showers and thunderstorms
are expected to develop along the front still parked across
mainalnd South Florida this afternoon. As a surface trough in the
Gulf edges south, northwesterly breezes will reestablish
themselves across our waters perhaps creating an easier path into
our area for some of mainland`s convection or outflow boundaries.
Recent CAM runs cannot seem to agree on whether or not showers
will form ahead of mainland`s influence, but generally agree that
something will be crossing the Keys from the north later today.
Thus opted to hold 50 PoPs for today and continuing with a 40%
into tonight. Rain chances peak for the forecast period starting
tomorrow as the front finally looks to shift further south. How
that is going to effect the rest of the forecast is still in flux
of course, so stay tuned.
&&
.FORECAST...
Issued at 248 AM EDT Thu Sep 11 2025
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 1135 AM EDT Thu Sep 11 2025
No watches, warnings, or advisories are currently in effect for
the coastal waters of the Florida Keys. From synopsis, a weak
surface trough draped across South Florida. This will keep a very
moist and unsettled environment across our area. A stalled front
across Florida is expected to slide southward into the Straits
this weekend. As a result, rain chances will remain elevated while
winds firm up slightly and clock from northwest to northeast.
With that said, there is considerable uncertainty as stronger
breezes will not be far off to the north and light and variable
breezes are expected just to our east.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  80  90  78  89 /  40  60  70  60
Marathon  79  89  78  87 /  40  60  70  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