Area Forecast Discussion
Issued by NWS Key West, FL

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520
FXUS62 KKEY 220317
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1017 PM EST Thu Nov 21 2024

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

.DISCUSSION...
Issued at 1015 PM EST Thu Nov 21 2024
A deep cyclonic circulation over the Ohio Valley is giving an
early taste of wintry weather across the Northeast and central
Appalachians, with a classic deep trough axis tilting to the
northwest with height across Florida and the Gulf of Mexico. All
this to say finally a deep influx of continental air becoming
entreched across the Keys. The evening sounding confirmed a thin
layer of moisture trapped beneath a 6C inversion based near 2200
feet off the surface. North-northwest winds were calculated around
28 knots beneath this inversion with deep cool air advection
aloft. Temperatures across the island chain were narrowly confined
in the upper 60s to around 70F, and while the thin stratocumulus
has pulled back westward and southward, no doubt the general
mid-70s sea surface temperatures across Florida Bay and Gulfside
are having a moderating effect. Still, it`s not a bad start to
true late autumn weather with the radar clear of precipitation
echoes and precipitable water values falling to below half of what
they were calculated at Key West 24 hours ago.

Overnight, little change is expected with mesoscale guidance still
anticipating a noctural density surge off the Everglades beginning
during the early morning hours, with forecasted temperatures
in the lower to mid 50s just north of the Bay. While upper Keys
winds are just starting to become occasionally breezy, windy
conditions are still expected to set in before dawn with no public
forecast modifications necessary.

&&

.MARINE...
Issued at 1015 PM EST Thu Nov 21 2024
Small Craft Advisories will remain in effect for all Florida Keys
coastal waters overnight. Winds were observed from the northwest
around 18 to 23 knots sustained along the reef as well as well-
exposed Gulfside locations. From synopsis: Fresh to occasionally
strong northwest to north breezes are expected overnight. Moderate
to fresh northwest to northerly breezes will continue through
Friday night, with considerable diurnal speed variations. High
pressure will then advance eastward through the Gulf Coast states
this weekend resulting in winds relaxing and veering to northeast
to east.

&&

.AVIATION...
(00Z TAFS)
Issued at 1015 PM EST Thu Nov 21 2024
VFR conditions are expected to prevail overnight into Friday.
Stratocumulus cloud bases in the FL025-030 range may produce a
brief moments of MVFR at EYW overnight, with the general trend
favoring higher, above-MVFR bases toward morning. For Marathon,
skies will likely stay clear. North-northwest winds are expected
to continue 13 to 17 knots with frequent gusts near 25 knots
overnight at EYW, with winds at MTH increasing after 06Z near
those levels as well.


&&

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

&&

$$

Public/Marine/Fire...JR
Aviation/Nowcasts....JR
Data Acquisition.....MJV

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