Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 140219
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
919 PM EST Fri Jan 13 2017

.SYNOPSIS...
A frontal system will stall near the area through the weekend. A
cold front will approach the area before weakening during midweek.

&&

.NEAR TERM /THROUGH SATURDAY/...
1040mb+ surface high will move eastward from the Great Lakes and
into New England tonight and on Saturday. This is causing low
level cold air to seep southward and into our region tonight.
Temperatures have fallen into the 30s across the northern third of
the area and will continue to fall through the rest of the night.
By morning, expecting temperatures near or just below freezing in
most locations, with the exception of parts of central VA and
southern MD where mid 30s likely.

Waves of light precipitation will move across the area tonight and
into Saturday, and with low level and surface temperatures near
freezing, this will set the stage for a light mixed precipitation
event. With marginal temperatures at onset, precip likely to start
out as rain/sleet, with freezing rain where it does fall below
freezing, and possibly some snow, mainly across Maryland and West
Virginia. Precipitation will then transition to a mix of sleet and
freezing rain/rain on Saturday. Models currently differ on depth
of low level cold and this will determine on how much sleet versus
freezing rain occurs. Temperatures then may rise slightly Saturday
afternoon, with some places going back to plain rain before
tapering off to light precip/drizzle. With light precip amounts,
marginal cold, and warm ground temperatures before the event, ice
amounts won`t be excessive for most locations. Highest
accumulations likely across the higher elevations where coldest
layer is modeled between 1000 and 3000 feet in elevation.

Thus total snowfall amounts light, under an inch, and mainly
confined to central/northern Maryland and portions of WV. Ice
accumulations generally a trace to a tenth of an inch for most
locations in the advisory area, except up to two tenths across
the higher terrain. DC/Baltimore metros a trace to a few
hundredths.

&&

.SHORT TERM /SATURDAY NIGHT/...
Precip will become more spotty Sat
night with temps slowly rising. There could be a few spots along
the Mason-Dixon line that remain below freezing Sat night, but
most areas will be above freezing.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
High pressure will be centered
to our northeast while a frontal boundary will be to our
southwest. The boundary stalls while the high pressure moves to
our east. Some guidance suggest that the boundary will be closer
to our CWA, increasing PoPs over our region, while some other
guidance keeps us dry. It is expected that the boundary will lift
north as a warm front on Tuesday followed by a cold front on
Wednesday.

Guidance is again in disagreement with what will happen with the
front. Some guidance stalls it to the south while other pushes it
east and away from us, so one dryer scenario than the other.
Temperatures will be near normal on Monday, followed by a warming
trend Tuesday into Wednesday. We have to see what will happen with
the Wednesday cold front.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions this evening will deteriorate into MVFR/IFR,
possibly LIFR, during the overnight hours and Saturday/Saturday
night as low clouds and light mixed precipitation moves overhead.
Icing concerns exist at MRB/IAD/BWI/MTN, and to a lesser extent,
DCA. CHO has lowest risk of seeing freezing rain. Area should then
begin to dry out with improving conditions Sunday, before
additional precip is possible Sunday night.

Frontal boundary near our region could bring some precipitation
on Monday. Warm front lifts on Tuesday and cold front moves
through on Wednesday. Therefore precipitation is still possible
through Wednesday possibly bringing sub-VFR conditions.

&&

.MARINE...
Northerly winds below SCA will continue tonight before becoming light
and variable Saturday and Saturday night.

Frontal boundary near our region could bring some precipitation
on Monday. Warm front lifts on Tuesday and cold front moves
through on Wednesday. Therefore precipitation is still possible
through Wednesday, while winds are expected to stay below
threshold.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Winter Weather Advisory from midnight tonight to 6 PM EST
     Saturday for DCZ001.
MD...Winter Weather Advisory from midnight tonight to 6 PM EST
     Saturday for MDZ003-004-013-501>504.
     Winter Weather Advisory from 4 AM to 6 PM EST Saturday for
     MDZ005-006-011-014-505>508.
VA...Freezing Rain Advisory from midnight tonight to 6 PM EST
     Saturday for VAZ025-026-507-508.
     Winter Weather Advisory from midnight tonight to 6 PM EST
     Saturday for VAZ027>031-040-052>054-501-502-505-506.
     Freezing Rain Advisory until 6 PM EST Saturday for VAZ503-504.
WV...Winter Weather Advisory from midnight tonight to 6 PM EST
     Saturday for WVZ050>053-055-502>504.
     Freezing Rain Advisory until 6 PM EST Saturday for WVZ501-505-
     506.
MARINE...Small Craft Advisory until 1 AM EST Saturday for ANZ533-534-
     537-542-543.

&&

$$
SYNOPSIS...LFR/MM
NEAR TERM...MM/LFR
SHORT TERM...IMR
LONG TERM...IMR
AVIATION...MM/IMR/LFR
MARINE...MM/IMR/LFR


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