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000
FXUS62 KKEY 201850
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
250 PM EDT Sat Apr 20 2024

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

.DISCUSSION...
Issued at 155 PM EDT Sat Apr 20 2024
Water vapor imagery highlights a broad belt of westerlies across
the CONUS. The subtropical ridging is displaced well to the south
into South America, with weak westerlies covering the Caribbean.
Surface observations place a stationary front across the Deep
South, south of a linear line of thunderstorms near the Red River
Valley and northern Louisiana. High pressure centered northeast
of the Bahamas supports gentle southeast breezes across the Keys
this afternoon. Temperatures are in the mid 80s and dewpoints are
near 70. The KBYX radar is echo free and skies are sunny. Low
level cumulus is muted across South Florida and Cuba, denoting the
widespread subsidence and dry air across the basin.

.FORECAST...
The low-level ridging will recede to the east tonight through
Sunday as lower heights spread southeast into the Mississippi and
Ohio River Valleys. A cold front will slide slowly down Florida
and the eastern Gulf on Monday, then pivot through the Keys Monday
night. MOS guidance is steadfast with single digit POPS through
the frontal passage, likely due to the diffluent BL flow. There
will be very little air mass change on the back side of the front,
but a legit wind shift to the north then northeast are expected
Monday night and Tuesday.

For Tuesday and Tuesday night, the cold core low currently racing
east towards the Baja will phase with the lower heights already in
the Gulf of Mexico. The paltry moisture from the front will linger
near the Keys as winds shift to the east Tuesday night and
Wednesday. Forecast soundings describe limited inhibition and ML
CAPE profiles near 1000 J/kg. The overnight crew hinted at thunder
probabilities Wednesday/Wednesday night at shift change, and we
agree. Low-level forcing will be weak and steering flow initially
from the northwest will turn variable. We will hold off on another
cycle to let the cold core low enter into the Mexican upper air
system.

A large anticyclone will start to take shape over the western
North Atlantic Thursday through Saturday while mean layer ridging
builds back into the Gulf and the Southeast. Fair weather and
moderate to fresh easterly breezes will resume the normal spring
time pattern. Of note, in a month`s time, the average high
temperature will increase four degrees (highest rate of the year)
from 83F to 87 F. Even the mention of a cold front is a welcome
gift for late April.

&&

.MARINE...
Issued at 155 PM EDT Sat Apr 20 2024
There are no watches, warnings, or advisories currently in effect
for the coastal waters of the Florida Keys. High pressure over
the western North Atlantic will maintain gentle to occasionally
moderate southeast breezes across the Florida Keys coastal waters
through the weekend. Gentle southerly breezes on Monday will
become moderate from the north Monday night, as a weak frontal
boundary slides through South Florida and the Keys. High pressure
over the Southeastern states will bring moderate easterly breezes
back to the Keys waters by the middle of next week.

&&

.AVIATION...
(18Z TAFS)
Issued at 155 PM EDT Sat Apr 20 2024
VFR and dry conditions will prevail at both EYW and MTH island
terminals through the TAF period. Near-surface winds will remain out
of the southeast at near 10 knots.

&&

.CLIMATE...
On this day in 1997, the daily record low temperature of 61F and
58F was recorded in Key West and Marathon, respectively. April
temperature records for Key West date back to 1872, and back to
1951 for Marathon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  76  84  76  84 /   0   0   0  10
Marathon  76  86  76  86 /   0   0   0  10

&&

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

$$

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

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