593 
FXUS62 KKEY 072006
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
306 PM EST Sun Nov 7 2021

.DISCUSSION...
Water vapor imagery highlights an upper level ridge sliding
northeast across the Plains, upstream of a developing nor'easter
to the east of the Carolinas. Cyclonic mid-upper level flow and 
dry, sinking air is across the southern Gulf, the Keys, and the 
southern tier of Florida. A 1027 mb surface high centered near
Tennessee supports moderate to fresh, northwest to north breezes
across the Florida Keys. Winds are a couple knots higher than
expected, which may be related to the deepening SFC low to the
east of South Carolina. Temperatures across the island chain are
in the mid to upper 70s with dewpoints in the lower to mid 60s.
The sensor on top of the KEY tower recently measured a dewpoint
of 57, the lowest we can remember so far this year. 

.FORECAST...
The upper level ridge will migrate east tonight through Tuesday
night, driving the nor'easter east into the western North
Atlantic. The surface high will remain over the Southeast United 
States, although its southeastern flank will fill the void 
previously occupied by the departing coastal storm. The cool and
dry airmass over the Mainland will surge to the south later
tonight, then again on Monday night. Pennekamp measured a low of
62 this morning, and tonight's lows should be a couple degrees
cooler, not only for the Upper Keys, but for most of the island
chain. Dewpoints on Monday afternoon will fall into the upper 50s
for many island communities, the driest air so far this season.

Breezes will diminish Tuesday through Wednesday as the surface
high bulges to the southeast in response to lower heights sliding
east through the Plains and Mississippi River Valley. Surface
winds will veer as the high builds southeast, allowing BL moisture
to finally make a return on Thursday. We advanced the timing of
the 30% rain chances to Thursday, and held onto the 40% chances 
Friday and Friday night as the flow becomes more confluent beneath
falling heights aloft. The next cold front is progged for Saturday
or Saturday night, followed by another blast of continental
northerlies on Sunday.  

&&

.MARINE...
Small Craft Advisory in effect for the Straits of Florida from
Ocean Reef to Craig Key due to north swells as high as 7 to 8
feet. Small Craft Should Exercise Caution across the remaining
coastal waters of the Florida Keys due to north winds 15 to 20
knots. From synopsis, a low pressure system to the east of 
Georgia supports moderate to fresh breezes. As this low slowly 
moves further northeastward tonight through Tuesday, breezes will 
slacken and turn to the northeast.

&&

.AVIATION...
VFR conditions will prevail at both the Key West and Marathon 
terminals through this evening and overnight. Surface winds will 
be generally out of the north near 12 knots with occasional gusts 
near 20 knots. After sunset, winds will drop a knot or two and 
become less gusty, but will increase again and become gusty near 
sunrise and through the morning hours as a mainland density 
current (cooler air over the mainland) overspreads the Keys island
chain.


&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  67  75  66  78 / -  0 -  10 
Marathon  65  75  66  78 / 0 0 10 10 

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory for GMZ052-072.

&&

$$

Public/Marine/Fire...CLR
Aviation/Nowcasts....Devanas
Data Acquisition.....DR

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