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009
FXUS62 KKEY 230828
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
428 AM EDT Sun Jun 23 2024

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

.DISCUSSION...
-- Changed Discussion --
Issued at 428 AM EDT Sun Jun 23 2024

After a lull during the late evening hours into the overnight
period, convective coverage has increased considerably across the
Keys area during the last couple of hours, with radars currently
showing numerous showers and scattered thunderstorms over the
Straits, spreading into eastern Hawk Channel and the Upper Keys.
Temperatures along the island chain are in the upper 70s to lower
80s, with dewpoints in the mid to upper 70s, and winds on land
mostly from the northeast at 5 mph or less. Surface analysis
depicts high pressure over the western Atlantic, with a weak ridge
extending across the Florida peninsula, and weak low pressure in
the Bay of Campeche. Aloft, a large mid/upper level low continues
to spin over the southwestern Atlantic, splitting the subtropical
ridge and maintaining general weakness aloft over our region. The
00Z Key West sounding sampled a very moist and conditionally
unstable airmass, with PW of 2.22 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.

Today looks to be another wet day across the Keys, as the
combination of copious tropical moisture, troughing aloft, and low
level speed convergence as a brief bout of somewhat stronger E/SE
flow pushes into our area should all support scattered to numerous
showers, with the potential for any of them to produce lightning
at any time. Have bumped PoPs up to 60 percent, which is still
below some of the guidance. Otherwise, expect a partly to mostly
cloudy day, with limited sunshine and rainfall holding high temps
to the upper 80s.

The conditions supporting above normal rain chances will change
only slowly during the next few days, as general troughing aloft
lingers over the SW Atlantic and Florida, with deep tropical
moisture remaining stuck across our region. Have increased rain
chances for tonight through Tuesday from the previous forecast,
although not as high as the very wet NBM guidance, and still below
some of the MOS guidance as well.

Mid level ridging should finally build to some extent across the
area during the middle and later part of the week, with PWs
eventually dropping closer to normal for this time of year. Low
level WSW flow may support reverse island cloud lines each day.
Nudged PoPs up to 40 percent for Tuesday night and Wednesday in
better agreement with the latest guidance, then continued with
slightly above climo PoPs around 30 percent from Wednesday night
through Friday.
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&&

.MARINE...
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Issued at 428 AM EDT Sun Jun 23 2024

Winds collapsed across the Keys coastal waters during the late
evening hours, but have recently begun to pick up from the east
again across eastern sections. While no marine headlines are in
effect, numerous showers and scattered thunderstorms will 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 gentle to
moderate east to southeast breezes across the Keys coastal waters
today, becoming light to gentle tonight through Monday evening.
The western Atlantic ridge will settle southward into the Florida
Straits during the middle and later part of the week, with light
southwest to west breezes prevailing over the Keys waters.
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&&

.AVIATION...
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(06Z TAFS)
Issued at 428 AM EDT Sun Jun 23 2024

VFR conditions are generally expected at both EYW and MTH today.
Multiple waves of scattered showers and some thunderstorms are
expected to cross the island chain throughout the day with those
passing over either terminal possibly resulting in bouts of sub VFR
visibilities and CIGs. VCSH is included at both terminals throughout
the TAF period as uncertainty for the exact timing and location of
showers is very high. Short-term amendments will be issued as
needed. Outside of any shower or thunderstorm, near surface winds
will be light and variable early, becoming east to southeasterly at
6 to 10 knots.
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&&

.CLIMATE...
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On this day in 1995, a record rainfall of 0.70" was measured in
Marathon. Rainfall records for Marathon date back to 1950.
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&&

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

$$

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

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