554 
FXUS62 KKEY 130829
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
429 AM EDT Mon Sep 13 2021

.DISCUSSION...
Currently - A surface through lower level ridge extends broadly
across the southeastern United States and the adjacent Atlantic.
This is producing gentle to moderate easterly breezes across the 
Keys and surrounding waters. Last evenings sounding is likely 
somewhat contaminated by an outflow boundary that swept through 
the area a few hours earlier, but it did indicate some low level 
inhibition which is consistent with shower activity struggling to 
hold together through the evening hours. The sounding did indicate
precipitable water above 2 inches,, but a bit below the ~2.25 
estimate of latest derived satellite imagery. Radar activity has 
more recently been trending upwards, with much of the activity 
concentrated over our eastern and southeastern waters.

Forecast - Over the next couple of days the surface ridge acros
the southeastern United States will gradually retreat eastwards
into the Atlantic as Tropical Storm Nicholas migrates northward
through the western Gulf of Mexico. The local pressure gradient
will gradually relax and winds will trend downwards. For the near
term, deep layered moisture will remain about half an inch above
normal for this time of year. This along with a still healthy flow
and at times no inhibition will continue the wetter than normal
pattern. Will advertize likely pops for today, trending to high
chance tonight. Outside raincooled areas, expect overnight lows to
be near 80 and highs near 90.

Heading into mid week an upper level low meandering over the
greater Antilles and Bahamas will help to amplify a surface 
trough over or just northeast of the Bahamas. As this trough 
develops and tracks towards the Carolina Coast, expect the local 
pressures gradient to open up and winds will slacken significantly
out of the southeast. Winds may go variable at times due to day 
time heating over the nearby large land masses. Rain chances 
should slip to near or slightly above normal due to the slackening
flow and the reintroduction of more persistent but still weak 
lower level inhibition and slightly drier air above the boundary 
layer. 

In the latter part of the week the surface through lower level
ridge will build westward across Florida as Nicholas and the
Carolina low lift northeastward into the northeastern United
States. With the ridge nearby, surface winds are expected to
become gentle out of the east. Rain chances will remain generally
near to slightly above normal due to weak inhibition and slightly
above normal deep layered moisture.

&&

.MARINE...
A ridge across the southeastern United States and adjacent
Atlantic will shift eastward further into the Atlantic as Tropical
Storm Nicholas arcs north then northeastward into the northwestern
Gulf states. Winds will relax further out of the southeast as a
surface trough/low develops near or northeast of the Bahamas and
Nicholes likely begins lifting northeastward through the central 
and eastern Gulf states. 

&&

.AVIATION...
Shower activity is beginning to increase across the area yet again 
after a brief lull. Another wet day is expected at both terminals. 
There will likely be periods with decreased shower coverage 
throughout the TAF period, however, due to the uncertainty of timing 
and location, have included VCSH through tomorrow morning. Surface 
winds will be from the east at around 7 to 10 knots. 

&&

.CLIMATE...
On this day in 1987, the daily record warm low of 86F was recorded 
in Marathon. This is also tied as the warmest low temperature 
recorded during the month of September. Temperature records in 
Marathon date back to 1950.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  88  80  89  80 / 40 50 40 40 
Marathon  88  80  90  79 / 50 50 40 40 

&&

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

&&

$$

Public/Marine/Fire...11
Aviation/Nowcasts....NB

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