Area Forecast Discussion
Issued by NWS Sterling, VA

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996
FXUS61 KLWX 060210 AAA
AFDLWX

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
910 PM EST Mon Dec 5 2016

.SYNOPSIS...
High pressure will briefly build over the region tonight.
Coastal low pressure will impact the area Tuesday into Tuesday
night before high pressure briefly returns again for Wednesday. A
potent cold front will pass through Thursday and arctic high
pressure will build overhead during the weekend.

&&

.NEAR TERM /TONIGHT THROUGH TUESDAY NIGHT/...

Clouds have thickened across most of the area early this evening.
Light rain is falling over far southern VA and North Carolina.
Precip will begin to overspread the far southwest corner after
06Z, but most probably after 09Z. Current temps and dewpoints
suggest precip will fall initially as light rain. After a few hrs
of saturation, temps may drop below freezing at the higher elevs
for rain to freeze on contact. There is good model support for
fzra in Highland, Pendleton and the western portions of Grant,
Mineral, Alleghany counties. There are also two RAWS stations,
Nathaniel Mtn (3004 ft) in Hampshire county WV and North Zone
Portable RAWS in western Rockingham (3830 ft) where current
dewpoints are low enough to support wet-bulb temps below freezing.
Have thought about expanding the current winter wx advzy east to
include Hampshire, Hardy, Augusta and Rockingham counties, but the
areal coverage of fzra seems too small to warrant an advzy for
the entire counties. There is also weak support for fzra over the
Blue Ridge mtns, however, dewpoint has been rising at Wintergreen
and is currently at 37F. So, fzra appears highly unlikely at this
time. Sub-freezing air could linger over the highlands through
most of the day according to the 12Z ECMWF ensembles, so current
advzy looks good in areal coverage and expiration time. Rain
moderate to heavy at times will fall over the rest of the area and
should begin to taper off between 00Z-03Z Wed. Total precip
amounts of 0.5 to 1.0 inches are expected with up to 0.20 inches
of frza possible over the highlands.

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The shortwave trough will move across the region Tuesday night.
Temperatures will likely max out in the 30s and around the low 40s
across the I-95 corridor Tuesday afternoon/evening. Temps will
slowly rise into the evening however winds will become NW by Wed
morning and cool dry air will move into the region.

Sunny conditions expected Wednesday with temperatures reaching the
40s and 50s along I-95. A cold front will approach the region

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A storm system will approach from the west Thursday and Thursday
night. A chance of rain or snow showers exist across the region each
period. Precipitation should be light in intensity with chilly
temperatures.

High pressure is expected to build in from the west Friday through
Saturday night. This high could bring the chilliest air so far this
season. Some upslope snow showers could also occur in the Potomac
Highlands.

The high will move offshore of the East Coast Sunday ahead of the
next approaching trough of low pressure Sunday night into Monday.
This next storm system could bring a chance of wintry precipitation
at the onset Sunday night, change over to rain, before ending as a
little snow sometime on Monday. The confidence in the timing and
precipitation type is low. The 12z GFS model is moving this storm
system eastward much faster than the 00z European model. We will
have to see how the 12z European model handles the storm.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...

LIFR/VLIFR conditions expected 12Z Tue-06Z Wed across all
terminals in moderate to heavy rain. Cigs and vsbys begin to
improve after 06Z Wed.

VFR conditions expected Wednesday.

Mvfr to ifr conditions possible in any rain or snow showers Thursday
and Thursday night. Winds variable 5 to 10 knots Thursday becoming
northwest and increasing 10 to 15 knots gusts 20 knots Thursday
night.

&&

.MARINE...
High pressure will build overhead tonight before coastal low
pressure impacts the waters Tuesday. A Small Craft Advisory is in
effect for portions of the waters Tuesday afternoon.

No marine hazards expected Thursday. Small craft advisories possible
Thursday night. Winds becoming northwest 15 to 20 knots gusts 20 to
25 knots Thursday night.&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     MDZ501.
VA...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     VAZ503-504.
WV...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     WVZ501-503-505-506.
MARINE...Small Craft Advisory until 5 PM EST this afternoon for
     ANZ530>543.
     Small Craft Advisory from noon to 6 PM EST Tuesday for
     ANZ532>534-537-540>543.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     MDZ501.
VA...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     VAZ503-504.
WV...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
     WVZ501-503-505-506.
MARINE...Small Craft Advisory from noon to 6 PM EST Tuesday for
     ANZ532>534-537-540>543.

&&

$$
SYNOPSIS...HSK
NEAR TERM...LFR
SHORT TERM...HSK/LFR
LONG TERM...KLW
AVIATION...LFR/KLW
MARINE...LFR/KLW



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