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Area forecast discussion 
National Weather Service Miami Florida
1022 am EST Sat Dec 20 2014

Update...
another dry and warm day is underway across South Florida with a
few clouds and southeasterly winds. Moisture will continue to
increase across the area through the day and into tonight with
westerly flow aloft. This will result in an increase in cloud
cover overnight and is reflected in the ongoing forecast. No
updates are planned at this time.

&&

Previous discussion... /issued 627 am EST Sat Dec 20 2014/

Aviation...

VFR conditions will prevail at all South Florida terminals with a
light southeast surface wind. There could be some patchy fog
before sunrise over the interior and affect only ktmb. However,
chances are low and have not placed in the taf. The light wind
will allow for a southwest coast sea breeze after 17z.

Previous discussion... /issued 413 am EST Sat Dec 20 2014/

Discussion...

A benign upper air pattern continues during the first half of the
weekend across much of the nation. A flat upper level high will
be centered over the Caribbean with zonal flow over Florida and
the southeast. High pressure consolidating over New England and
the middle Atlantic later this weekend, will wedge down the eastern
Seaboard creating a stationary boundary along the southeast coast,
onto which a few areas of low pressure will ride from the Gulf of
Mexico and across northern Florida. Although a combination of
surface easterly winds and midlevel S to SW winds will produce
more clouds, slightly cooler temperatures and an increase in moisture
through the column, the weekend is expected to remain dry across
South Florida. Showers will develop ahead of one of these
disturbances moving through the Gulf of Mexico and northern
Florida Sunday night. The operational GFS has been the wettest and
farthest south with quantitative precipitation forecast across South Florida for a couple of runs.
The rest of the model suite has been drier and further north,
although a few showers and maybe a thunderstorm can't be ruled out
in the warm moist sector, mostly for the northern half of the
County Warning Area, through Monday.

The upper pattern will amplify into early next week, mainly in
response to a strengthening upper high/ridge nearing the western
Continental U.S.. several shortwaves plunging over the crest of the western
ridge will carve out a trough through the Midwest which will drive
a cold front into South Florida Wednesday morning/afternoon. Before
then, Tuesday is expected to be warm and humid for this time of
year, just ahead of the front with deep southerly flow.

Long range guidance has been showing it's typical fast bias with
cold fronts in the extended, delaying its passage by about 6hrs
with each run. If we take this into consideration, the best
chance for rain across the East Coast cities may be second half of
the morning or early afternoon Wed, with frontal passage more
towards lunch or the second half of Wednesday. Confidence will
grow as the event nears. Model sounding convective available potential energy above 1k j/kg elicits
at least a chance for thunderstorms with the front, most likely
across the lake region. Colder air and dry high pressure then
quickly arrives for Christmas. The forecasted placement of the
surface high is in the optimal position for decoupling and a
chilly Thursday night/Friday morning for the interior. As the
anticyclone moves east, easterly flow dominates with moisture
slowly returning from offshore late next week.

Marine...

High pressure this weekend deivers easterly flow. A cold front
will approach the Gulf waters late Tuesday and move through the
Atlantic waters on Wednesday. Winds will veer to the south and
southwest midweek, then northwest and north into Christmas. Expect
building seas, especially through the offshore Gulf waters, by the
middle of next week.

&&

Preliminary point temps/pops...
West Palm Beach 78 66 78 69 / 0 0 10 20
Fort Lauderdale 77 68 79 70 / 0 0 10 10
Miami 78 68 79 69 / 0 0 10 10
Naples 76 63 78 66 / 0 0 10 20

&&

Mfl watches/warnings/advisories...
Florida...none.
Am...none.
GM...none.
&&

$$

Update...10/cd
aviation...71/je

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