911
FXUS62 KKEY 040201
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1001 PM EDT Tue Jun 3 2025

...New DISCUSSION, MARINE, AVIATION...

.DISCUSSION...
Issued at 1000 PM EDT Tue Jun 3 2025

CIMSS composite vorticity analysis places a slow-moving, cut-off
upper- level low centered in the eastern Gulf off of the Florida
Sun Coast. This has placed the Florida Keys in a region of upper-
level divergence and associated synoptically-forced ascent for
much of the day. Meanwhile, at the surface, a quasi-stationary
front draped over Central Florida continues to disintegrate, with
surface high pressure now centered just off the Carolinas
promoting mean surface easterlies. Despite the widespread shower
and scattered thunderstorm activity across the Keys and adjacent
coastal waters, we were successfully able to conduct a 00z
evening balloon launch at KEY. The sounding sampled an
uninhibited, largely saturated environment, coupled with minimal
CAPE to be realized. However, owed to the aforementioned synoptic
features, the sounding also revealed impressive 0-3 km helicity of
around 275 m2/s2, supportive of occasionally rotating cells
across boundary interactions.

For the overnight period, recent radar trends have certainly been
downward, with most shower activity feeding in the surface
southeasterlies quickly waning, indicative of at least temporary
mean subsidence. After a lull in activity, our attention turns to
a wave of Saharan dust approaching the eastern Bahamas, based on
satellite- derived precipitable water products. The leading edge
of this feature is progged to approach the Keys several hours
before sunrise, which may provide additional forced ascent, and
what very well be the last gasp of more widespread rainfall and
scattered thunderstorms for the next several days. Given the
current light to moderate stratiform precipitation across much of
the Island Chain and the potential for this second wave of
activity late in the first period, have elected to let the
inherited short-term forecast ride, including high PoPs. No
changes proposed for this late evening forecast update cycle.

&&

.MARINE...
Issued at 1000 PM EDT Tue Jun 3 2025

Due to continued widespread shower and isolated thunderstorm
activity across the Keys coastal waters, wind directions remain
quite variable, often quickly shifting along convective
boundaries. The copious boundary interactions continue to result
in bouts of confused seas, lasting through the overnight period.
Outside of any convection, fresh to strong southeasterlies are
expected to resume later tonight, warranting a continuation of
Small Craft Advisories overnight.

From synopsis, an upper-level low in the Gulf of America will
continue to promote a very active weather pattern across our area
overnight through at least Wednesday morning. Expect strong gusty
winds, sudden wind direction shifts, and locally rough and
confused seas with the stronger activity. A surface high pressure
system will move eastward off the Eastern Seaboard, linking up
with a North Atlantic ridge. This high will move out into the
Atlantic later this week, resulting in a return to gentle to
moderate east to southeast breezes and less rainy and thundery
conditions.

&&

.AVIATION...
(00Z TAFS)
Issued at 1000 PM EDT Tue Jun 3 2025

Occasional sub-VFR ceilings and visibilities will be possible
through around 04/03z, before scattered shower and isolated
thunderstorm activity lulls. Additional storm development will be
possible by around 04/08z, with potential impacts to the terminals
including gusty winds and sub-VFR visibilities through around
04/12z, before activity wanes again. Due to the uncertainty in the
evolution of the second round of activity, elected to keep
mention of thunder out of the TAF at this time, although this will
be reevaluated after 04/06z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  88  77  88  82 /  80  70  60  50
Marathon  86  77  88  82 /  80  70  60  40

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory until 5 AM EDT Wednesday for GMZ031>035-
     042>044-052>055-072>075.

&&

$$

Public/Marine/Fire...BT
Aviation/Nowcasts....11
Data Acquisition.....MC

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