794
FXUS62 KKEY 211738
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
138 PM EDT Fri Aug 21 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...

- Conditions remain somewhat favorable for an island cloud line
  and associated waterspouts through late afternoon.

- Rain and thunder chances will return to near normal over the
  weekend through early next week.

- With highs near 90 and dewpoints in the mid to upper 70s,
  afternoon heat indices will peak at 105 to 108 degrees.

&&

.AVIATION...
(18Z TAFS)
Issued at 130 PM EDT Fri Aug 21 2026
VFR conditions will prevail at both Florida Keys island terminals
through 18z Saturday afternoon. The best chance for any isolated
vicinity shower will be late afternoon and early evening due to
possible island cloud line formation, mainly in the vicinity of
EYW. Chances for development are low due to a current BKN cirrus
deck, although this will be monitored over the next several
hours. Near- surface winds will generally be light out of the
southeast to south through the TAF period, although winds will go
VRBL at times through this evening.

&&


.PREV DISCUSSION...
Issued at 259 AM EDT Fri Aug 21 2026
The Florida Keys will remain within a weak flow pattern today
characterized by a split ridge orientation divided by deep-layer
troughing over the Southeastern US. The center of the col region
will shift slightly to our west in response to a subtle westward jog
of the surface ridge over the Bahamas which will promote more of a
southeasterly component to our winds today, especially across the
Middle to Upper Keys and surrounding coastal waters. Nonetheless,
expect generally light SE breezes becoming variable at times during
the afternoon. Waterspout potential should not be quite as high as
it was yesterday given less variability in the wind profile, but
will still need to monitor cloud line development this afternoon due
to the weak flow, particularly near the Lower Keys. The nearly 2"
PWATs sampled by the 00Z KKEY RAOB would suggest ample support
for routine showers and thunderstorms, but latest hi-res forecast
soundings suggest an arriving pocket of drier low-level air will
drop PWATs back down into the 1.4-1.6" range along the Island
Chain while deeper moisture content will be found over the
Southeastern Gulf. I have maintained a chance for thunderstorms
in the Gulf with models suggesting scattered development in the
10-14Z time frame.

Heading into the weekend, a cold front associated with the
aforementioned trough over the Southeast will advance south and
stall along the Gulf Coast region as the trough axis becomes
oriented along the Eastern Seaboard. SAL dust concentrations over
the Keys will become mostly negligible as moisture pools ahead of
the frontal boundary, and 1000-500mb RH values will, at times,
range from 60-70% as southeasterly flow becomes more established.
As such, expect a seasonable August forecast over the weekend
with near-normal rain chances and hot and humid conditions. Highs
in the lower 90s and dewpoints in the mid to upper 70s will
result in continued heat stress and afternoon head indices in the
105-108 degree range.

&&

.MARINE...
Issued at 1030 AM EDT Fri Aug 21 2026
Conditions will be somewhat favorable for island cloud line
formation, mainly in the vicinity of the Lower and Middle Keys.
Any cloud line may produce a few waterspouts. Mariners are
reminded that a waterspout would most likely appear beneath a
dark, flat bottom of a building cumulus line, just at the hint of
rain.

From synopsis, a split ridge pattern remains in place across
the Florida Keys coastal waters. This will promote generally light
to gentle southeast to south breezes today, becoming variable at
times during the afternoon. As North Atlantic ridging builds
westward, southeasterly breezes will become more established over
the weekend, becoming gentle and at times moderate during the
overnight hours, continuing through early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  91  82  92  82 /  10  10  20  10
Marathon  90  82  90  82 /  10  10  20  20

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...BT
Aviation/Nowcasts....BT
Data Acquisition.....BT

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