Special Marine Warning 236, NWS Key West, FL

Area Forecast Discussion
National Weather Service Key West FL
332 PM EDT Sat Oct 9 2021

.DISCUSSION...
South-central Florida has erupted into a cluster of strong
thunderstorms. Visible satellite imagery highlights confluent flow
to the west of Naples and northeast of the Bahamas, and weakly
cyclonic flow across Central Florida. The storms formed south of
the cyclonic curvature and east of the confluence, within a broad
sector of rich tropical moisture. Steepened mid-level lapse rates
associated with a maturing long wave trough axis continue to
spread south through Florida. To the northwest of the Florida
Keys, bands of confluent and convergent flow are thickening into
agitated cumulus, and these bands will continue towards the Keys
over the next few hours. Along the island chain, a thin and
emaciated cloud line has struggled with vertical development. With
the resplendent sunshine, a hot and humid October afternoon across
the Florida Keys.

.FORECAST...
The maturing mid-upper level cyclone digging south-southeast
through Florida will remain a weather player across the Florida
Keys for the next week. Several short waves embedded within the
long wave axis will coalesce into a cutoff cyclone within the next
day or so. At first this cyclone will be centered just to the
north of the northern Bahamas, then lumber to the south towards
central Cuba, all-the- while staying east of the Florida Keys.
This will not matter though because occasional bulges along its
western flank will introduce episodes of DCVA across the Keys. Low
level vorticity analyses highlight a developing low pressure
system near the Carolinas, with a lobe extending southwest across
Florida. The storms firing over south- central Florida this
afternoon are ahead of this lobe. We expect the tail- end of this
low level cyclonic curvature to push into the Keys this evening,
in conjunction with steep mid level lapse rates and moist and
confluent BL southwesterlies. We highlight 60% rain/thunder
chances for the island chain tonight, and some storms sliding
southeast off of South Florida could be strong this evening.
Thereafter, steering will shift from southwesterly on Sunday, to
south-southeasterly on Monday, to easterly by Wednesday. Dry
layers between 850-500 mb will limit coverage Sunday night through
Monday night, followed by a developing deep tropical profile. We
highlight 30% rain/thunder chances from Sunday through Saturday,
noting continued signals for a period of very heavy rains
Thursday through Saturday if the festering upper low can instigate
lower pressure across the Western Caribbean.

&&

.MARINE...
There are no watches, warnings, or advisories currently in effect
for the coastal waters of the Florida Keys. Light to gentle
breezes will prevail this evening through Tuesday, followed by
freshening breezes Tuesday night and Wednesday as high pressure
builds back into the southeastern United States. Tonight and
Sunday an unsettled weather pattern will increase the coverage of
showers and thunderstorms. Winds and seas will be higher in and
near showers and thunderstorms.

&&

.AVIATION...
Previous reasoning from this morning terminal forecasts continue on
its course. With higher than normal chances of rain, there are
chances for showers and thunderstorms late this afternoon and
tonight. Moreover, VCTS conditions are included in the current
terminal forecasts. Otherwise, winds will be light and out of the
west northwest.

&&

.CLIMATE...
On this day in 2009, the daily record warm low temperature of 84
degrees was recorded in Key West. This is also tied for the warmest
low temperature ever recorded in October. Temperature records in Key
West date back to 1873.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  77  85  78  86 / 50 30 20 20
Marathon  77  86  77  87 / 60 40 30 30

&&

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

Public/Marine/Fire...CLR/TW
Aviation/Nowcasts....NB
Data Acquisition.....SMS

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Hazardous Weather Outlook...UPDATED
National Weather Service Key West FL
837 AM EDT Sat Oct 9 2021

FLZ076>078-GMZ031>035-042>044-052>055-072>075-101245-
Monroe Upper Keys-Monroe Middle Keys-Monroe Lower Keys-
Florida Bay including Barnes Sound, Blackwater Sound, and
Buttonwood Sound-
Bayside and Gulf side from Craig Key to west end of Seven Mile
Bridge-
Gulf waters from East Cape Sable to Chokoloskee 20 to 60 NM out
and beyond 5 fathoms-
Gulf of Mexico including Dry Tortugas and Rebecca Shoal Channel-
Gulf of Mexico from west end of Seven Mile Bridge to Halfmoon
Shoal out to 5 Fathoms-
Hawk Channel from Ocean Reef to Craig Key out to the reef-
Hawk Channel from Craig Key to west end of Seven Mile Bridge out
to the reef-
Hawk Channel from west end of Seven Mile Bridge to Halfmoon Shoal
out to the reef-
Straits of Florida from Ocean Reef to Craig Key out 20 NM-
Straits of Florida from Craig Key to west end of Seven Mile
Bridge out 20 NM-
Straits of Florida from west end of Seven Mile Bridge to south of
Halfmoon Shoal out 20 NM-
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry
Tortugas out 20 NM-
Straits of Florida from Ocean Reef to Craig Key 20 to 60 NM out-
Straits of Florida from Craig Key to west end of Seven Mile
Bridge 20 to 60 NM out-
Straits of Florida from west end of Seven Mile Bridge to south of
Halfmoon Shoal 20 to 60 NM out-
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry
Tortugas 20 to 60 NM out-
837 AM EDT Sat Oct 9 2021

This Hazardous Weather Outlook is for the Florida Keys and
adjacent coastal waters.

.DAY ONE...TODAY AND TONIGHT

Isolated thunderstorms are expected. The primary thunderstorm
hazard will be lightning strikes.

The Key West tide gauge has measured high tides about a half foot
above the predicted tides for the past several days.
A Coastal Flood Statement in effect for the Florida Keys through
Sunday morning

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

Sunday and Sunday night, isolated to scattered thunderstorms are
expected. The primary thunderstorm hazards will include lightning
strikes and locally heavy downpours.

Monday through Friday, isolated thunderstorms are expected. The
primary thunderstorms hazard will be lightning strikes.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.