Key Largo, Florida Weather Forecast Discussion

675
FXUS62 KKEY 181753
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
153 PM EDT Thu Sep 18 2025
...New AVIATION, PREV MARINE, DISCUSSION, AND FORECAST...
.AVIATION...
(18Z TAFS)
Issued at 148 PM EDT Thu Sep 18 2025
Scattered showers and isolated thunderstorms will continue to lurk
in the vicinity of the terminals through much of the evening
hours. Due to the chaotic nature of the convection, opted for just
an inclusion of a general period of VCSH for now, with specific
impacts to visibilities and ceilings left to future TAF amendments
with possible TEMPOs. Activity is expected to wane in the late
overnight period, and VCSH mention is removed from then through
the end of the TAF period. Outside of any storm, near-surface
winds will remain generally out of the northeast to east at 7 to
10 knots.
&&
.MARINE...
Issued at 1134 AM EDT Thu Sep 18 2025
No watches, warnings, or advisories are in effect in for the
Florida Keys waters. From synopsis, weak upper-level troughiness,
coupled with a decaying frontal boundary draped over the Florida
Peninsula, will support bouts of above normal rain chances through
tonight. As drier air pushes across the Keys and high pressure
builds across the Eastern Seaboard, drier conditions, coupled with
light to gentle northeast to east breezes, are expected for
Friday through the weekend.
&&
.PREV DISCUSSION...
Issued at 1134 AM EDT Thu Sep 18 2025
The 12z morning sounding at KEY sampled a substantial stable, dry
layer from the surface to around the 700 mb isobaric level,
following widespread showers and isolated thunderstorms overnight.
Over the past hour or two, the atmosphere appears it has begun to
recharge, with available KAMX nearby Doppler radar highlighting
scattered showers and thunderstorms, mainly over the central and
eastern Keys marine zones. Composite atmospheric analysis places
a lifting upper-level trough in the northern Gulf, and a decaying
low- level trough extending southwestward to the Florida Peninsula
from a filling area of low pressure off New England. CIMSS MIMIC
tropospheric-integrated precipitable water product shows an
expansive area of 2.25-2.50" upstream of the Keys all the way to
Andros Island. The forecast calls for one more wet and potentially
thundery afternoon, with drier conditions on the horizon beyond
tonight. No changes proposed for this late morning update package.
&&
.FORECAST...
Issued at 414 AM EDT Thu Sep 18 2025
A weak synoptic pattern will persist across South Florida and the
Keys through the upcoming week. A stalled boundary in the
vicinity of the Keys, combined with Atlantic high pressure to the
north will maintain a moist flow. Precipitable water values near
or above 2 inches will support periods of showers and
thunderstorms through the end of the week as deep moisture spills
through the region. Aloft, flow remains weak which will favor
slow-moving convection causing higher rainfall amounts over the
island chain. Convergence zones will act as the primary trigger
for convection development though as the week progresses
thunderstorms will become less favorable while rain is still
likely. Surface winds will generally remain from the east to
southeast while elevated speeds will start to slacken throughout
the coming days. Temperatures will remain warm and humid with
daily highs in the upper 80s and lows in the upper 70s.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...BT
Aviation/Nowcasts....BT
Data Acquisition.....BT
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NWS KEY Office Area Forecast Discussion