Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 140900

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EST Sat Jan 14 2017


A cold front is positioned over southern Virginia. A large area of
high pressure is moving into northern New York state. The front
will remain to our south before returning north as a warm front
Tuesday. A weak cold front will push through the area Wednesday.
High pressure looks to be in control of the weather late in the



As of 330am, a 1044mb surface high is centered over Ottawa with a
surface ridge extending south across the Mid-Atlantic. Upper level
high pressure is centered over FL with a plume of gulf moisture
arcing around this high from the mid-South states to the mid-
Atlantic. A swath of precip is oriented east-west across the area
from Petersburg, WV to Calvert Co MD. This should enhance the cold
air damming wedge and draw dewpoints in the teens farther south. A
sharp north edge to the precip has developed with this particularly
dry air to the north.

It has taken awhile tonight for precip to get going and the wet bulb
temperature is yet to be realized. Freezing rain is expected to
overspread the area through the middle morning hours. Therefore, no
changes to the headlines will be made at this time. Guidance
consensus is for echoes to fill in to the north where snow should at
least mix in.

The 00Z GFS and ECMWF veer the wind south through the morning hours.
However, this appears to be a case where models erode cold air
damming too soon given the precip developing over the area. Will
have to continue to adjust the forecast based on observations and
new high res guidance.



Reinforcing high pressure should break the wedge tonight with dry
NWly flow ending precip this evening. Therefore, no extension to the
headlines have been made yet.

A warm front lifts into the area Sunday night with low chances of
mainly rain over the SWrn half of the CWA. High pressure shifts
offshore Monday with a return southerly flow developing, beginning
a warming trend.



We are approaching what is climatologically the coldest time of
the year...but there really isn`t any signal that implies cold
air is coming our way.

The front which is currently analyzed as being over southern
Virginia looks to remain in the Carolinas over the next few days
before pushing to the north Tuesday as a warm front in response to
a short wave moving through the Mississippi Valley. This will
bring about a chance for rainshowers. Highs are expected to be in
the 50s.

The short wave and an attendant cold front will push through the
area Wednesday. Another chance for showers. Depending on the time
of the fropa Wednesday could see 60 degrees.

After the front passes through Mid Atlantic looks to be under
high pressure through Friday. Highs in the 50s...lows around
40. The average temperatures for this time of year are lows 40s
for highs...mid 20s for lows.



MVFR conds developing across the DC metros with IFR cigs likely as
cold air damming enhances over the area. A wintry mix through
sunrise with mainly light freezing rain then through the rest of the
morning hours across the DC metros. Temperatures remain low through
the afternoon before precip tapers off tonight.

Warm front brings low chances for rain west of the DC metros Sunday
night, the high pressure develops with VFR conds Monday.

Rain showers are possible Tuesday through Wednesday. Brief MVFR
periods will be possible as well.



Winds expected to remain below SCA criteria Tuesday and Wednesday.


DC...Winter Weather Advisory until 6 PM EST this evening for DCZ001.
MD...Winter Weather Advisory until 6 PM EST this evening for MDZ003-
     Winter Weather Advisory until 6 PM EST this evening for MDZ005-
VA...Freezing Rain Advisory until 6 PM EST this evening for VAZ025-
     Winter Weather Advisory until 6 PM EST this evening for
WV...Freezing Rain Advisory until 6 PM EST this evening for WVZ501-
     Winter Weather Advisory until 6 PM EST this evening for


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