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Area forecast discussion...updated
National Weather Service Miami Florida
1034 am EST Mon Jan 22 2018

Update...
morning dense fog advisory was allowed to expire as the fog over
inland southwest Florida has dissipated. Updated zones were
transmitted to remove the headlines. Otherwise, the forecast
appears to be on track with little change anticipated through the
rest of the afternoon.

&&

Previous discussion... /issued 617 am EST Mon Jan 22 2018/

Aviation...
generally VFR with shower chances increasing later in the period
as a front approaches. Some sub-VFR morning fog and low clouds
could impact the terminals over the next few hours, particularly
at apf. Flow will veer from the east to south-southeast over the period.

Previous discussion... /issued 531 am EST Mon Jan 22 2018/

Update...
patchy fog has developed in portions of the interior. Reports of
visibility of one eighth to one quarter of a mile form Hendry
County as well as northern interior Collier County. Therefore, a
dense fog advisory has been issued for most of the interior areas.

Previous discussion... /issued 400 am EST Mon Jan 22 2018/

Discussion...
models are coming into better agreement with the weather for the
week. A weak 500mb ridge is sliding across the region today, as a
surface high, sitting to the northeast, begins to be pushed off to
the east. This is advance of a low pressure system currently over
the plains.

A strong 500mb low will move from the Central Plains, to the
northeast, and is progged to be over the Great Lakes region by
tomorrow morning. This system has a fairly vigorous surface low
associated with it. Models indicate that the low should remain
around 995mb for the next couple of days, with some fluctuation in
strength. This will bring a cold front out of East Texas and
across the Gulf states today and tonight. However, by tomorrow,
the low is pulling off to the northeast, somewhere north of
Buffalo, New York by mid Tuesday morning. This will pull much of the
energy away from South Florida. The GFS has moistened up quite a
bit since yesterday mornings run, and is now in better agreement
with the European model (ecmwf) with the precipitation actually making it to the
County Warning Area. It is just much weaker than it would be if the low had
tracked further south.

Ahead of the front models are indicating there could be around
1000 j/kg of cape over the area for Tuesday afternoon. With
diurnal heating, this could allow some thunderstorm activity to
pop up. So, have added a slight chance of thunderstorms for all of
South Florida for tomorrow afternoon. 500mb temps are showing to
be around -9c on the NAM sounding and a touch colder on the GFS.
The NAM model sounding is showing freezing level of around 13k.
This would also favor the development of some thunderstorm
activity.

The models have progressed the front further away from the
area, not stalling it until it is well over the Florida Straits
now. The GFS is quicker with the front, drying the area out by
Wednesday. The European model (ecmwf) on the other hand slows the front down as it
moves through. This would keep some shower activity over the
region through the day on Wednesday. Given this, kept a low end
chance of showers for much of the area through Wednesday
afternoon.

This front is not particularly strong for South Florida.
Temperatures on Wednesday do look about 5 to 10 degrees cooler,
but the dew points remain in the 60s for a couple days behind the
front.

By Thursday, high pressure is building well to the north of the
area. This high will bring a fairly tight pressure gradient to the
area, causing some breezy conditions, out of the east, to develop
for the latter half of the week. This may bring a few coastal
showers onshore for the Atlantic coast on Friday and Saturday.

By Sunday morning, the next low pressure system is progged to
developed over the northern Gulf. This low looks to attach itself
to a cold front that will be quickly moving across the central
US. This will increase rain chances for South Florida once again
for Sunday. Models indicate the front may begin to move through
the area Sunday night, with some uncertainty if it will clear the
area before the end of the forecast package. For now, have a
chance of showers in the forecast for South Florida, with maybe a
few thunderstorms on the southern Atlantic waters.

Marine...
seas are forecast to run 1 to 3 feet across the Atlantic waters
and up to 2 feet in the Gulf, for the next couple of days. A cold
front will bring a northeasterly to northerly wind to the region
Tuesday night. The front will also bring a chance of showers, and
perhaps some isolated thunderstorms on Tuesday as well. The front
is forecast to push out of the area sometime on Wednesday. High
pressure will build to the north beginning Thursday. This will
bring breezy conditions to all South Florida waters for the
latter half of the week, into the weekend. The wind will cause
seas to build to 7 to 9 feet by the end of the week.

The east wind today of 10 to 12 kts would correlate to a moderate
risk of rip currents. For the latter half of the week, a
northeasterly wind of 15 to 30 kts across the Atlantic waters
would result in a high risk of rip currents, which would likely
persist through the weekend.

&&

Preliminary point temps/pops...
West Palm Beach 77 68 79 64 / 10 20 40 50
Fort Lauderdale 77 69 78 66 / 0 20 40 50
Miami 79 71 80 67 / 0 20 40 40
Naples 81 66 77 63 / 10 30 40 10

&&

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

&&

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