104
FXUS62 KKEY 190831
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
431 AM EDT Fri Jul 19 2024

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

.DISCUSSION...
Issued at 430 AM EDT Fri Jul 19 2024

Showers have remained isolated across the area during the late
night hours, with radars currently detecting only a few showers
over the offshore Gulf waters and the distant eastern Straits of
Florida. Temperatures along the Keys island chain are hovering in
the mid 80s, with dewpoints in the mid to upper 70s, and winds on
land from the east to southeast around 10 mph. Surface analysis
depicts Atlantic high pressure extending westward across the
Florida peninsula and into the Gulf of Mexico. Aloft, the
subtropical ridge also extends westward from the Atlantic across
Central/South Florida and the central Gulf. While the 00Z Key West
sounding measured slightly above normal PW of 1.92 inches, more
recent MIMIC-TPW and GOES-TPW satellite imagery show a drier
airmass spreading into the Keys from the southeast, with estimated
PWs dropping to between 1.6 and 1.7 inches.

For today, the drier airmass currently spreading into our area
should keep rain chances below normal, and have maintained the
existing 20 percent PoPs. The main weather concern for today will
be the heat, with highs in the lower 90s and dewpoints in the
upper 70s driving heat indices as high as 110F during the midday
and afternoon hours. Accordingly, have issued a Heat Advisory for
all of the Keys from 10A this morning through 7P this evening.

A minor increase in moisture and ESE flow may bring a bump in
convective activity across the area tonight into Saturday morning,
then a relatively dry airmass for this time of year should prevail
across the area Saturday afternoon/night, ahead of a tropical
wave moving westward across the Caribbean and Greater Antilles.
Have continued with low chance (30 percent) PoPs for tonight
through Saturday night, but rain chances may end up being lowered
for Saturday afternoon/night, if the dry slot depicted by the GFS
during that time pans out. Otherwise, a Heat Advisory may be
needed again for Saturday with max heat indices currently forecast
around 110F.

The tropical wave will approach our area Sunday afternoon, with
the surface wave axis forecast to push through Sunday night, and
deep moisture in the wake of the wave lingering through Monday.
We expect increased rain chances in the 40 to 60 percent range
during this time, with the highest chances currently focused on
Sunday night. Temps may be slightly suppressed due to increased
cloud cover and rainfall, with highs around 90 and lows around 80.

Thereafter, the dominant Atlantic ridge pattern will resume. We
may see a TUTT approach our area from the east by around
Wednesday, but the lower level reflection of this feature appears
rather weak, and have opted to maintain low chance PoPs, which are
near climo, through the extended period at this time.

&&

.MARINE...
Issued at 430 AM EDT Fri Jul 19 2024

Late night observations show SE winds decreasing to around 10
knots along the reef and at Long Key C-MAN, with seas at Satan
Shoal running around 2 feet. No marine headlines are currently in
effect across the Keys waters, but there is the potential for
Small Craft Exercise Caution headlines on Saturday night. From the
synopsis, Atlantic ridging will remain across the Florida
Peninsula through Saturday, with gentle to moderate east to
southeast breezes continuing across the Keys coastal waters.
Breezes will increase during the weekend as the ridge strengthens
to our north. A tropical wave is forecast to move through the area
Sunday night and Monday, bringing an increase in rain and thunder
chances. Moderate east to southeast breezes will resume behind the
wave next week.

&&

.AVIATION...
(06Z TAFS)
Issued at 430 AM EDT Fri Jul 19 2024

VFR conditions will prevail at the EYW and MTH terminals through the
TAF period. As drier air moves into the area shower activity should
be limited today therefore VCSH is not included at this time.
Surface winds will remain from the east to southeast near 10
knots.

&&

.CLIMATE...
On this date in 1880, a temperature of 97F was recorded in Key West,
which is the warmest temperature ever recorded in July, and is tied
for the highest temperature ever recorded in Key West. Temperature
records for Key West date back to 1872.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 10 AM this morning to 7 PM EDT this evening
     for FLZ076>078.

GM...None.
&&

$$

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

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