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fxus62 kkey 082058 
afdkey

Area forecast discussion
National Weather Service Key West Florida
358 PM EST sun Dec 8 2019

Discussion...
water vapor imagery shows an upper level trough exiting the southeast US
coast and out over the western North Atlantic. Upstream a ridge
continues its eastward trek from Baja California into western
Mexico. Behind this feature the next upper level low is slowly
digging south along the California coastline. At the surface, a
pressure cell that was previously located on the New England coast
has emerged over the North Atlantic. To the West Lee-side
cyclogenesis is taking shape with weak, but strengthening surface
trough along and just east of the Palmer Divide. To the north of
this feature an Arctic high is dropping south through Saskatchewan
and beginning to nose into the northern High Plains.

A little closer to home, visible satellite shows fair weather cu
over the Florida Strait and butting up against the shoreline of
the Lower Keys. Given the lower level flow, these clouds have
pushed across the middle and Upper Keys, leading to generally
mostly sunny skies. Temperatures warmed a couple degrees in Key
West from the upper 70s this morning to just above 80 degrees, as
reported by the Airport ASOS. Meanwhile, the Middle Keys saw a
relatively considerable increase from the mid 70s to near 80,
while the Upper Keys maintained a near-steady state in the mid
70s. Winds have veered to the east while remaining around 10 mph
with some gusts to 15 mph. Key West radar detects no precipitation
over our region, though there are some isolated showers being
detected over southern Mainland. These however will stay well away
from our area.

Tonight through Tuesday night, surface high pressure off the New
England coast will strengthen and build southward with the ridge
axis setting up across central and southern Florida. This will
drive our winds to veer more solidly from the east, continuing to
veer to the southeast by Tuesday. During this period expect winds
to generally range from 10 to 15 mph. In addition, expect a
gradual warming trend with temperature returning into the lower to
mid 80s for all locations in the Keys. Likewise, a turn to the
east and eventually southeast will bring in more lower level
moisture with a two-fold impact. The first being that dew points
will rise into the lower 70s, the first time since Dec 2nd. The
second being that the chances for isolated showers will slightly
increase. The upper level ridge, currently centered over western
Mexico, will trek east and maintain large scale subsidence aloft.
Therefore, any showers that develop in the east/southeast wind flow would be
shallow and mesoscale in nature. Given the nature of these showers
and no large scale forcing, will keep pops at no higher than 20
percent through the period.

Wednesday and Wednesday night, we will see a lull in the wind as
the high pressure cell to our east moves sufficiently away in
advance of the aforementioned strengthening trough along the
Palmer Divide. This feature will strengthen into a closed off
surface low and move northeast into the Great Lakes region with a
trailing cold front that will eventually reach the Florida
Panhandle by Wednesday afternoon but really no further. Its
effect for the most part will not be felt in the Keys except for
the weakening gradient and brief diminishing of the winds. The
high pressure cell quickly descending from Saskatchewan, will
move in behind the low and emerge off the mid-Atlantic coast by
Thursday. This will serve to freshen breezes from the east/NE
Thursday and Thursday night. Beyond Thursday, there is uncertainty
with how the next upper level low will develop once it moves
ashore from California later this week. For now it appears that if
a surface low does develop in the central Gulf, it'll quickly
move northeast and remain north of our area.

&&

Marine...
Ridge axis will build south and settle across central and southern
Florida with breezes remain gentle to moderate through Tuesday
night. Winds will remain from the NE/east tonight and gradually clock
around to the east/southeast by Tuesday. A dying cold front over the Gulf
of Mexico will erode the western flank of the ridge axis Tuesday
night through Wednesday night, allowing breezes to diminish.
Another weak area of low pressure may develop over the Gulf of
Mexico Friday and quickly trek northeast.

&&

Aviation...
VFR conditions are expected at both island terminals for the rest of
this afternoon and evening, with periods of few to scattered cloud
coverage at around 2500-3000 feet. Northeasterly winds at around 8
knots will veer to easterly late this afternoon.

&&

Climate...
in 1986, the daily record rainfall of 6.66" was recorded at the
Key West Airport. This is also the wettest day ever recorded in
December.

&&

Key watches/warnings/advisories...
Florida...none.
GM...none.
&&

$$

Public/marine/fire...liw
aviation/nowcasts....bt
data collection......nb

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