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Area forecast discussion
National Weather Service Miami Florida
732 PM EST Mon Dec 11 2017

Update...as with last night, clear skies and light winds have
allowed temperatures to drop quickly across South Florida with
sunset. Another chilly night is on tap with temperatures
comparable to last night. No changes to the ongoing forecast.

&&

Previous discussion... /issued 645 PM EST Mon Dec 11 2017/

Aviation...VFR expected through the period with light and
variable winds tonight. West wind will pick up after sunrise on
Tuesday and persist through the day.

Previous discussion... /issued 332 PM EST Mon Dec 11 2017/

Discussion...

This afternoon and tonight: another clear and cool day across South
Florida, with temperatures running a few degrees warmer than Sunday.
Temperatures are currently maxing out in the mid-upper 60s, and
will fall quickly after sunset under clear skies and light winds.
Overnight lows will be a few degrees warmer in the interior in the
upper 30s and low 40s, with the Gulf Coast and East Coast similar
to last night in the mid-upper 40s, along with a few low 50s along
the immediate coast east of 95.

Tuesday through thursday: shortwave driving the current system
moving through the upper Midwest will swing south and east into
Tuesday. The associated surface low will follow the main upper level
low into New England and the Canadian Maritimes while dragging a
frontal boundary through the southeast and Florida.

With pwats currently near record lows across the region and little
moisture recovery expected over the next 24 hours, expected little
more than a modest increase in cloud cover and breezy west-northwest
winds during the day on Tuesday. The front will reinforce the cool
and dry airmass in place across the Florida Peninsula. While high
temperatures on Tuesday will be in the low to mid 70s, expect a dip
where temperatures struggle to get out of the 60s on Wednesday.
Temperatures return back into the low 70s on Thursday. Overnight
lows will likely be coldest behind the front Wednesday night, but
generally remaining in the low-mid 40s across the interior, upper
40s for the Gulf Coast and interior East Coast Metro, and low 50s
for the immediate coastal areas of the East Coast Metro.

Friday into next weekend: the large and relatively strong upper
level trough will continue to dominate the eastern half of the US as
we head into next weekend. The parade of stronger shortwaves moving
through the trough will also continue, with the next one of note
moving through the southeast late this week into the weekend. Timing
and strength differences remain between the GFS and ECMWF, but both
show another front moving through the state Friday or Saturday.
Models also differ as to if this will be a clean frontal passage or
if the boundary lingers through the weekend. Regardless, this will
likely be the next appreciable chance of rainfall across South
Florida.

Marine...a dry frontal passage will bring a surge of west to
northwest winds on Tuesday, with speeds picking up to 15 to 20 knots
by late in the afternoon. Speeds may be a steady 20kts at times,
especially overnight Tuesday into Wednesday morning and an advisory
may be needed during this time. High pressure quickly rebuilds
across the state on Wednesday with north-northwest winds diminishing
to 10kts or less on Thursday. Winds may pick up again into the
weekend with another frontal boundary. No significant rain chances
are expected through most of the upcoming week.

Fire weather...relative humidity values will bottom out around 30% for most of
the region this afternoon, with no issues expected with overnight
recovery. Breezy west-northwest flow on Tuesday will bring an
improvement in dispersions, which will be very good to excellent
during the afternoon. Relative humidity values will generally be above critical
levels, though the East Coast may drop to 35-40%. Light winds on
Wednesday will lead to poor dispersions again, with a reinforcing
dry airmass allowing relative humidity values to drop back into the mid 30s. Erc
values may approach critical values through the period.

&&

Preliminary point temps/pops...
West Palm Beach 43 72 50 69 / 0 0 0 0
Fort Lauderdale 51 74 52 69 / 0 0 0 0
Miami 51 74 55 69 / 0 0 0 0
Naples 47 73 55 66 / 0 10 10 0

&&

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

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