Upper Matecumbe Key, Florida Weather Forecast Discussion

514
FXUS62 KKEY 141905
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
305 PM EDT Sun Sep 14 2025
...New AVIATION...
.AVIATION...
(18Z TAFS)
Issued at 305 PM EDT Sun Sep 14 2025
VFR conditions are expected to prevail at both EYW and MTH
through the rest of today and into tonight. A cloud line has
formed along the Lower and Middle Keys this afternoon, but
precipitation is having trouble developing and sustaining with
dry air aloft. Will leave mention out unless required. Near
surface winds will be light and variable.
&&
.PREVIOUS DISCUSSION...
Issued at 1108 AM EDT Sun Sep 14 2025
Mostly sunny skies have found their way to the Florida Keys this
morning as dry air has finally settled aloft after several days of
wet conditions. GOES-19 visible imagery notes some fair weather
cumulus strung across the island chain associated with old
outflow boundaries. While our land areas have been free of
precipitation, KBYX radar has detected some showers percolating
in the Straits of Florida and more recently the Deep Gulf waters.
A few of these showers have briefly grew to thunderstorm strength
but are short-lived. Light and variable winds observed along the
Reef help explain the nearly stationary movement of any convection
that does form. Meanwhile, current temperatures on the island
chain average in the mid 80s with dewpoints still stuck in the mid
70s.
The short term forecast looks to remain rather quiet to kick off
the week. This morning`s KKEY 12z sounding closely resembles
yesterday evening`s sounding with dry air intruding throughout
the thermodynamic profile. The observed PW has now dropped to
1.57 inches, or below the 25th percentile for today. CIMMS MIMIC
TPW confirms this change with drier values stretched across the
majority of Florida and the eastern Gulf. Southeasterly winds are
observed at most levels of the atmosphere confirming a deep layer
trough axis lies perhaps just off to the west of our area.
Considering the amount of dry air aloft, a lack of flow, and poor
upper level support for convection, slight chance PoPs continue
to be appropriate in the short term. The front south of our area
will crawl back to the north starting sometime tomorrow resulting
in increasing rain chances by the middle part of this coming week,
so enjoy the dry spell while it lasts.
&&
.FORECAST...
Issued at 517 AM EDT Sun Sep 14 2025
Forecast soundings, consistent with synoptic analysis, suggests
the Florida Keys will finally be in a convective lull over the
next 48 hours or so, as the frontal boundary that has flirted with
the Island Chain remains well displaced to the south. The reprieve
from the rainfall will likely only be short-lived, as the front
nudges back northward Tuesday. The front then appears to stall yet
again in the vicinity of South Florida. As a sprawling area of
high pressure in the North Atlantic interacts with this frontal
feature, easterly breezes will freshen as well, supporting
elevated speed convergence and correlated elevated rain chances.
Despite brief bouts of rain-cooled temperatures, highs will reach
the upper 80s to near 90, with lows in the upper 70s to near 80.
&&
.MARINE...
Issued at 1108 AM EDT Sun Sep 14 2025
No watches, warnings, or advisories are currently in effect for
the coastal waters of the Florida Keys. From synopsis, a weak
frontal boundary will remain in the vicinity of the Florida Keys
coastal waters over the next several days. Weak undulations of
this feature, interacting with high pressure to its immediate
north, will result in a low confidence forecast for winds and rain
chances. Gentle to moderate northeast to east breezes are
expected to build in by Tuesday afternoon or night, as the axis of
the high pressure finally is able to spread down closer to the
Keys marine zones.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  79  90  80  90 /  20  30  30  40
Marathon  79  89  80  89 /  20  30  30  40
&&
.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