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afdkey

Area forecast discussion
National Weather Service Key West Florida
254 PM EDT Wed Oct 16 2019

Discussion...
water vapor imagery highlights a broad mean-layer ridge centered
over the Florida Keys and western Cuba. The low-level ridge axis
is across the Keys as well, lending to gentle southwest breezes
across the coastal waters. The one outlier is Carysfort Reef,
where southwest winds have increased to 12 knots due to the
heating of South Florida. This morning's kkey radiosonde observation sampled 1.80"
of pw, moderate instability, and plenty of dry air above 800 mb.
Since then, we have watched visible satellite imagery an the slow
erosion of the low level cumulus as the Cuban shadow worked
northward. A brief Lee-side cloud line formed between Big Pine Key
and the Middle Keys. Most of the island chain remains rain free.

Forecast...
a powerful Nor'easter will develop tonight, dragging weak cyclonic
low-level curvature through Florida. Meanwhile, a short wave
trough over the Texas- Mexico border will erode the northwestern
flank of the mean- layer ridge. Baroclinic forcing from the short
wave will act upon a weak area of low pressure (see early
afternoon ascat) over the Bay of Campeche on Thursday and Thursday
night. To the north of this system along the Gulf Coast, a stalled
frontal boundary will entangle with the developing low over the
Gulf. A sloppy and elongated area of low pressure is expected to
move northeast toward the northern Gulf Coast Friday and Friday
night.

Despite all this action over the Gulf and the eastern United
States, the Keys will feature slim rain chances and light breezes
through Thursday night. Isallobaric forcing Friday through
Saturday night will result in freshening south-southeasterly
breezes and increased rain chances. By Sunday, the subtropical
ridge will build across Florida, lending to gentle to moderate
east- southeasterly breezes and near normal rain chances Sunday
night through Wednesday.

&&

Marine...
no current watches, warnings, or advisories. A ridge axis will
linger over the coastal waters of the Florida Keys tonight through
Thursday night. An area of low pressure will move northeastward
across the west- central Gulf of Mexico Friday through Saturday.
When areas of low pressure develop over the Gulf, wind speeds are
normally significantly higher than model predictions. We have
trended winds higher Friday through Saturday night based on this
experience. High pressure will build west across Florida Sunday
through Monday.

&&

Aviation...
VFR conditions are expected at both eyw and mth terminals for the
rest of this afternoon and evening. While a developing cloud line
may produce a few showers, the window of opportunity is closing.
Light southwesterly winds will become variable after 00z.

&&

Key watches/warnings/advisories...
Florida...coastal flood advisory for flz076- 077.

GM...none.
&&

$$

Public/marine/fire...clear
aviation/nowcasts....bt
data collection......kbl

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