306 
FXUS62 KKEY 260914
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
514 AM EDT Sun Sep 26 2021

.DISCUSSION...
The convective activity last night worked the atmosphere enough 
that any shower activity has been few and far between. KBYX is 
only detecting isolated showers in the Straits of Florida. The 00Z
sounding showed a decrease in PW in comparison to the values we 
have been seeing over the past week, coming in at just under 2 
inches. Satellite derived TPW highlights very dry air across most
of the United States that extends down as far as Central Florida.
The Keys are right on the edge of this drier air, but are still 
in a swath of near normal moisture. Marine observation platforms 
are currently recording winds ranging from 4 to 7 knots across the
nearshore coastal waters. With the lower winds still prevailing
this morning, the larger islands have been able to radiate into 
the upper 70s while the rest of the island chain is closer to near
80 degrees. High pressure has started building into the region, 
and winds will increase today in response. Have kept near normal 
rain chances for today and tonight as moisture is expected to 
linger around through tomorrow morning. Temperatures are expected
to peak near 90 degrees this afternoon.

Moisture is expected to decrease as we head into tomorrow, and 
will remain low through around Wednesday night. Forecast 
soundings show abnormally low PWs settling across our area as a
surface high over the southeast shuttles in drier continental air.
In addition to keeping rain chances low and thunder chances non- 
existent for the first part of the week, dewpoints will also drop 
in response to this very welcome drier air. While dewpoints look 
to only drop into the upper 60s to near 70 degrees, it will 
definitely help it feel slightly less muggy than the oppressive 
summertime dewpoints of the mid to upper 70s usually do. As we 
head into the latter half of the week, a trough will sweep off the
East Coast starting between Tuesday night and Wednesday. This 
will deform the surface high over the East Coast and allow more 
moisture to enter the scene starting on Thursday. Rain and thunder
chances will return back to near climatology (~30%) during this 
time. Thereafter, the gradient will tighten as a strong high 
pressure centered over the Northeast builds into our area. We 
could start seeing winds increase as early as Wednesday night. 
Winds will remain elevated through the weekend. There is some 
discrepancy in the guidance as to what we can expect this weekend 
in regards to rain chances, with some models showing drier air 
returning and others not. Due to this uncertainty, have retained 
near normal rain chances. Temperatures will remain seasonable, 
with highs in the upper 80s to near 90 degrees and lows in the 
upper 70s to near 80 degrees.

&&

.MARINE...
There are no watches, warnings, or advisories currently in effect
for the coastal waters of the Florida Keys. From synopsis, High 
pressure will build over the southeastern United States today and
tonight, leading to freshening northeast to east breezes. An 
extended period of moderate northeast to east breezes are expected
Monday through Thursday. A trough will shift the high pressure 
off to the east through the week. Breezes will further freshen 
starting Wednesday night as another strong high pressure builds 
into the region.

&&

.AVIATION...
VFR conditions will prevail at both the Key West and Marathon 
terminals through the forecast period. Northeast to east breezes 
will freshen to gentle to moderate by this afternoon. Chances for 
rain look very low for this morning, becoming better by the 
afternoon. With that said, confidence is too low at this time to 
include mention of VCSH for either terminal.

&&

.CLIMATE...
On this day in 1920, the daily record cold high temperature of 
78F was recorded in Key West. This is also tied for the coldest 
high temperature ever recorded in September. Temperature records
date back to 1872.

&&

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

$$

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

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