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000 
FXUS62 KMFL 120032
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
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. 

&&

.PREV 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.

PREV 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...RH 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. RH 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 RH 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...
FL...None.

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