Area Forecast Discussion
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950
FXUS62 KKEY 161555
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1055 AM EST Tue Jan 16 2018

.DISCUSSION...
High pressure is just east of the Appalachians with an axis
reaching from eastern Canada to the northern Gulf Coast. Strong
northeast breezes peaked overnight as the gradient tightened along
the southern flank of the surface high. Most exposed marine
locations recorded winds approaching 25 knots.

The coastal shelf gulf and bayside of the island chain has cooled
considerably over the past few days. The Key West Harbor gauge
indicates 68F, corroborated by the SST analyses courtesy of the
NASA SPoRT group. We launched our KKEY RAOB at 6AM this morning,
which sampled northeast winds of 31 knots at 1 kft. At the same
time, the Key West ASOS registered sustained winds of 10 knots
with no gusts. This is a testament to the amount of decoupling
provided by the cooler shelf waters during northeast flow, sans
CAA.

The forecast calls for winds to slowly decrease this afternoon,
especially in the lee of South Florida. Highs will reach the
lower to mid 70s and rain chances remain slight. We dropped
Florida Bay from the Small Craft Advisory, otherwise, no changes
needed or planned. The next wind surge accompanied by CAA will be
Wednesday night.

&&

.MARINE...
Small Craft Advisory remains in effect for the all Coastal Waters
of the Florida Keys, except Florida Bay. Winds peaked overnight at
most locations between 22 and 24 knots, with assumed winds in the
Florida Straits 26-28 knots. Winds have decreased since then, and
this trend will continue through the afternoon. Large seas in the
Straits will slowly subside, and portions in the lee of South
Florida will probably drop out of Advisory wind criteria (<20
kts) this afternoon. From synopsis, a ridge of high pressure,
from Eastern Canada to the northern Gulf Coast, will slide
eastward into the western north Atlantic this afternoon. A
reinforcing area of high pressure will build southeastward from
the Great Plains Wednesday, reaching North Florida by Friday.
Fresh to strong breezes will subside Friday and Friday night. High
pressure will strengthen across the western North Atlantic
Saturday and Saturday night, resulting in freshening easterly
breezes.

&&

.AVIATION...
VFR will prevail at the EYW and MTH terminals this afternoon.
Forecast soundings, statistical guidance, and analogue situations
indicate good chances for low level stratus at the terminals
around 12Z Wednesday. A relatively moist boundary layer atop
chilly coastal shelf waters will lend to the possibility of CIGS
based around 010. For now we have included no impacts at the
terminals, but will need to reassess this afternoon and evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  72  65  72  56 / 10 10 -  -
Marathon  74  65  72  54 / 10 10 -  -

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory until 5 PM EST this afternoon for
     GMZ032>035-042>044-052>055-072>075.

&&

$$

Public/Marine/Fire...CLR
Aviation/Nowcasts....CLR
Data Collection......KN

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