205 
FXUS62 KKEY 111627
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1127 AM EST Mon Jan 11 2021

.SHORT TERM...(Today through Wednesday)

Considerable warming and moistening has occurred in the lowest few
thousand feet of the KEY sounding over the past 24 hours. At EYW,
temperatures rose 6 degrees in a single hour between 3 and 4 am as
winds shifted from northeast to southeast off warm Gulf Stream
waters. This wind shift boundary has likely turned up stationary
over Bayside and Gulfside waters. Compared with 24 hours ago, Key
West is 12 degrees warmer, and the dewpoint is 13 degrees moister.
There is still a thick layer of dry air between 4,000 and 14,000
feet, which will maintain a dry forecast for at least the rest of
today, but the prevalence of altocumulus clouds jibes well with
the moist and unstable layer between about 600 mb and 400 mb.
Through Tuesday, this dry layer will narrow, but it will remain
the biggest impediment to rainfall development. This is in spite
of being on the southern periphery of a jet streak curring across
North Florida and the nearby proximity of the aforementioned wind
shift boundary. 


Looking upstream, a well-defined cold front is currently making
slow headway across the Central Gulf. The front will become more
diffuse on Tuesday but still manage to cross the Keys late in the
day. A turn to north and northeast winds will bring modest cooling
for Wednesday. The slightly cooler air mass will remain quite
shallow on Wednesday, with plenty of moisture and some leftover
elevated instability. Areas of light rain and scattered showers
will be possible on Wednesday, as the vigorous shortwave trough 
currently digging through the Sonoran Desert races east and passes
by to our north on Wednesday. This will provide some jet stream 
lift and should wash out any remaining mid-level dry air. 

&&

.MARINE...

Winds shifted from northeast to southeast over the islands during
the pre-dawn hours. This wind shift boundary is now somewhere over
the Bayside and Gulfside waters. It has likely turned up
stationary, and some of our guidance now pushes this boundary back
south across the Keys late this afternoon. Proximity of the 
boundary will lead to variable wind at times, though northeast 
winds will be driving its push back south. 

From synopsis...A cold front extended from the Florida Panhandle 
back across the Central Gulf this morning. The front will weaken 
as it reaches the Keys late Tuesday, but high pressure to its 
northwest will bridge across the boundary and bring a turn to 
moderate northeast breezes by Tuesday night and Wednesday. High 
pressure will move eastward off the Texas coast on Wednesday, 
passing east across the Gulf on Thursday, then dissipating near 
the Florida Peninsula on Friday. The next cold front will pass the
Keys around Friday night.

&&

.AVIATION...

VFR conditions will prevail at the Key West and Marathon terminals 
through 12/12Z. Southeast to South winds near 10 knots are likely to 
persist through this afternoon before becoming variable and 
decreasing to near 5 knots. Then tonight, winds will become 
predominantly east to northeast. FEW to SCT coverage around 3500 
feet and a second BKN deck around 15K feet.

&&

.CLIMATE...

On this date in 2010, Marathon recorded a low temperature of 39F.
This is the coldest temperature ever recorded during the month of
January.

&&

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

$$

Public/Marine/Fire...Haner
Aviation/Nowcasts....SDR
Data Acquisition.....LIW/LW	

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