Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 140900
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EST Sun Jan 14 2018

.SYNOPSIS...
Canadian high pressure will settle over the eastern U.S. today
and then begin to lift out Monday. A clipper system will bring a
cold front through the area Tue night. Low pressure will develop
offshore Wed or Thu followed by moderating temperatures and high
pressure for the late week.

&&

.NEAR TERM /UNTIL 10 AM THIS MORNING/...

Wind chills are in the single digits early this morning, except
lower teens in S MD and central VA, and below zero in the
mountains. The Potomac Highlands and Blue Ridge are maintaining
minus ten or lower wind chills, and the wind chill advisory
there continues until 10am.

&&

.SHORT TERM /10 AM THIS MORNING THROUGH TUESDAY NIGHT/...

Winds will gradually slacken today, but a cold day ahead with
temps not breaking out of the 20s. A clipper system will bring a
cold front thru the area late Tue, though the parent low will
remain well to our north. That will bring our next chance of
snow showers with some light accumulations possible.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...

Global models have remained consistent showing an upper trof
deepening as it approaches the area Wed inducing weak sfc
cyclogenesis offshore Wed afternoon and night. A period of light
snow appears possible Tue night in the west and in the east Wed as
heights fall across the area and forcing for upward vertical motion
increases with the approach of the upper trof. Some uncertainty
lingers mainly with respect to timing and QPF with the Euro being
slower and snowier than the GFS, but this should be in general a
light QPF event under 0.1 inches water equivalent but with
relatively high SLRs. At the worst case scenario, this could be a
marginal advisory event. Trof axis crosses the area at the latest
06Z Thu, earlier on the GFS with snow ending by midnight Wed night
across far southern MD if not a lot sooner.

Temps begin to moderate quickly on Thu as trof departs and heights
rise quickly. By the end of next weekend, we could be looking at
very mild weather with Euro showing exceptionally high heights.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...

VFR conditions until at least Tue when the clipper cold front
could bring some light snow and lower cigs and vsbys. Stronger
winds this morning will gradually weaken during the day and Sun
night.

Possible flight restrictions later Tue into Wed in light snow
eastern terminals as cold front, then upper trough, cross the
area.

&&

.MARINE...
Small craft advisory conditions will persist today, but winds
will weaken and should be below criteria by late today or later
this evening. After that, lighter winds will be in control until
the clipper cold front passes later Tue.

SCA conditions expected Wed and Thu with possible gales Wed
night.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Wind Chill Advisory until 10 AM EST this morning for MDZ501.
VA...Wind Chill Advisory until 10 AM EST this morning for VAZ503-
     504-507-508.
WV...Wind Chill Advisory until 10 AM EST this morning for WVZ501-
     503-505-506.
MARINE...Small Craft Advisory until 5 PM EST this afternoon for
     ANZ530>533-535-536-538>542.
     Small Craft Advisory until 11 PM EST this evening for ANZ534-
     537-543.

&&

$$
SYNOPSIS...CS
NEAR TERM...CS
SHORT TERM...CS
LONG TERM...LFR
AVIATION...CS/LFR
MARINE...CS/LFR



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