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639
FXUS62 KKEY 240820
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
420 AM EDT Mon Jun 24 2024

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

.DISCUSSION...
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Issued at 420 AM EDT Mon Jun 24 2024

Convective coverage has remained fairly muted across the Keys
region during the late night hours, with radar currently detecting
just widely scattered showers. Temperatures along the island
chain are mostly in the upper 70s to lower 80s, with dewpoints in
the mid 70s, and winds on land generally from the east to
southeast at 5 mph or less. Surface analysis depicts high
pressure over the western Atlantic, with a weak trough over the
Florida peninsula, and weak low pressure in the Bay of Campeche.
Aloft, a weak mid/upper trough remains in place across Florida and
the SW Atlantic. The 00Z Key West sounding sampled a very moist
and conditionally unstable airmass, with PW of 2.20 inches (well
over the 90th percentile for the date). More recent MIMIC-TPW
satellite imagery shows the Keys remaining embedded within a large
area of 2+ inch PWs extending from the Caribbean and Greater
Antilles WNW through much of the Gulf of Mexico.

Although shower activity has been limited across the area since
Sunday afternoon, the synoptic pattern (copious moisture and
general weakness aloft) would appear to favor another rather wet
day across the Keys. The potential fly in the ointment may be lack
of low-level forcing, as we don`t expect the ESE wind surge which
pushed into our area early Sunday morning and was likely the
trigger for widespread shower development during that time.
However, most of the CAM guidance does indicate considerable
convective development at some point during the day. Am not as
confident in rainfall as on Sunday, but will maintain 60 percent
PoPs for today, which is in general agreement with the MOS
guidance as well. Otherwise, expect another partly to mostly
cloudy day, with limited sunshine and rainfall holding high temps
to the upper 80s.

Guidance has trended a bit drier from tonight through midweek,
with the mid level trough now washing out more quickly than
previously depicted, while the upper trough shifts well east of
Florida. That said, our low-level flow will be shifting to the
WSW, as the subtropical ridge drops southward in response to a
couple of mid-latitude troughs moving off the East Coast. With
ample moisture remaining in place, we may be primed for reverse
island cloud line development each day from Tuesday through
Thursday. Have maintained mid-range chance PoPs (30 to 40
percent). Max temps will edge up to around 90F by midweek as we
should see more sunshine.

Late this week and into the weekend, the subtropical ridge should
shift back northward, allowing for more typical midsummer gentle
ESE flow to resume. See no reason to deviate from near-climo 30
percent PoPs at this time.
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&&

.MARINE...
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Issued at 420 AM EDT Mon Jun 24 2024

Late night observations show mostly light to gentle E/SE breezes
across the Keys coastal waters. While no marine headlines are in
effect, numerous showers and scattered thunderstorms are expected
to impact the waters today with locally strong wind gusts and
rough seas. From the synopsis, high pressure over the western
Atlantic and low pressure over the Bay of Campeche will maintain
light to gentle east to southeast breezes today. The western
Atlantic ridge will settle southward into the Florida Straits from
Tuesday through Thursday, with light southwest to west breezes
prevailing over the Keys waters. The ridge will shift back
northward late this week, allowing light to gentle southeast
breezes to resume.
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&&

.AVIATION...
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(06Z TAFS)
Issued at 420 AM EDT Mon Jun 24 2024

A lull in convection has settled across the Keys early this morning,
but shower coverage is expected to increase over the next several
hours. Have included VCSH at both terminals with a rough estimate of
when more showers will be present near the island chain. Short term
amendments will be issued as needed for possible impacts as
uncertainty in exact timing and location is high. Outside of
convection, near surface winds will be from the east to southeast at
6 to 10 knots.
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&&

.CLIMATE...
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On this day in 2009, a record rainfall of 1.67" was measured in
Marathon. Rainfall records for Marathon date back to 1950.
-- End Changed Discussion --

&&

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

$$

Public/Marine/Fire...Jacobson
Aviation/Nowcasts....JAM

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