Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 151533 AAA

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1033 AM EST Sun Jan 15 2017

High pressure will build over the area through tonight. A stationary
front over the southern Mid-Atlantic states will move north as a
warm front Tuesday. A weak cold front will push through the area


.NEAR TERM /THROUGH TONIGHT/...High pressure will build over the
area through tonight setting up a cold air damming event. Low
clouds will remain banked up against the mountains under
northeast flow with light rain developing early this evening over
the cntrl Shenandoah valley. Looking at hi-res models, NCAR 3-km
10-member ensemble and NAM-WRF 3-k parallel run, some pockets of
fzra are possible only over the higher elevs of the Blue Ridge
mtns and ridges in Shenandoah, Augusta and Rockingham counties.
Farther north, where temperatures are likely to drop below
freezing, no precip is expected. Have adjusted Wx and PoP grids
for tonight keeping northern areas dry roughly north of the
Potomac river.


Despite 1030mb surface high pressure building over the central mid-
Atlantic tonight, upper level lift/a developing warm front
associated with the SWrn low looks to bring rain into the area
tonight. There is a chance for a wintry mix late tonight on the
northern fringes of the precip shield that develops.

High pressure shifts offshore Monday with the warm front lifting
north of the area and return southerly flow developing. However,
little mixing during the day likely makes for a cooler Monday than
Sunday by a couple degrees.

Low pressure moves NE across the Great Lakes Tuesday with another
warm front entering the area. Areas of rain cross the area with a
quarter to a half inch of rain. Perhaps this is enough to close the
gap on our seasonal deficit.


One thing seems clear - cold air will be held at bay for the
extended part of the forecast in what is climatologically the
coldest time of the year.

Wednesday does look to start out showery as a short wave tracks
through the Mid Atlantic followed by clearing Wednesday afternoon/
overnight. Highs should climb into the 50s with lows staying above

Temperature-wise both Thursday and Friday should also see highs
rise into the 50s. Models do begin to disconnect for the second
half of the week - Euro has east coast under a ridge Thursday while
GFS shows a trough moving through. While we are in fast upper
level flow not sure the change is so rapid that another trough
will move over us...and prefer the drier solution.

By choosing the Euro depiction this would lead to the next short
wave approaching the region Friday. Because of this have added low
chance PoPs to the day. P-type would only be rain. This is still
over five days away so there will likely be alteration to the


IFR conditions now at KCHO only improving to MVFR this afternoon.
No wintry precip expected at any of the TAF sites tonight.

Light southerly flow develops Monday. Another warm front brings
south winds, rain, and IFR conds Tuesday.

Showers possible Wednesday then VFR Wednesday afternoon through


High pressure moves overhead tonight with light southerly flow
Monday through Tuesday.

Winds expected to remain below SCA values Wednesday and Thursday.




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