Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 021511

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1011 AM EST Fri Dec 2 2016

High pressure will gradually move into the region through Sunday.
An upper-level disturbance will pass through the area Sunday night
and high pressure will briefly return for Monday. Coastal low
pressure may impact the area Tuesday into Tuesday night before
high pressure briefly returns for Wednesday. A potent cold front
will move through late next week.


West-northwest flow will continue through this afternoon and
actually become re-enforced tonight as a system moves through New
England this afternoon, sending another push of modest cold-air
advection southeastward. Some of the earlier cloud cover has
dissipated over the metro, but it reamins thick to the NW.
Thinking remains that additional strato-cumulus clouds develop
this afternoon in the west/northwest flow. Overall theme should
be mostly cloudy north/west, mostly sunny south/east with a breeze
up to about 20-25 mph. Some upslope snow showers continue to be
possible along the Allegheny Front as well. Temperatures will be
right around climatological normals, with highs in the 40s/50s.


As mentioned, northwest flow/CAA gets somewhat re-enforced
tonight, so overall idea of partly/mostly cloudy north/west and
mostly clear south/east is expected to continue. Otherwise, near
normal temperatures with lows in the upper 20s to mid 30s.

High pressure over the midwestern US will slowly move eastward and
towards the region on Saturday, however the gradient between it
and the gradually departing system over southeast Canada will
still keep the area in a brisk northwest flow with gusts 20-25
mph. Again under northwest flow, theme of cloudier northwest and
clearer southeast should continue. High temperatures will be a
couple of degrees cooler than today, generally in the 40s to
around 50F.

High pressure will briefly be in control Saturday night into
Sunday morning leading to a slackening wind field and continued
dry weather. However, a weakening system coming out of the mid-
Mississippi Valley will lead to increasing clouds on Sunday,
followed by increasing chances for some light overrunning warm air
advection precip by late Sunday and Sunday night. Still several
days out, but the potential for some light frozen precipitation
exists, especially in northern/western and higher elevation
locations. Thermal profiles look to favor mostly rain from the
I-95 corridor southeast. Highs Sunday will be in the 40s for most,
with lows Sunday night in the 30s.


High pressure will briefly build overhead Monday from the
Midwest...likely bringing dry and seasonably chilly conditions.
Low pressure in the southern branch of the jet will track through
the southern Plains Monday before moving northeast toward the
Tennessee Valley Monday night.

As the low moves into the Tennessee Valley Monday night...clouds
will lower and thicken and precipitation will begin to overspread
the area from southwest to northeast. The low will slowly pass by
to our west Tuesday while it transfers energy to a coastal low.
Warm and moist air from the Gulf of Mexico and Atlantic Ocean
will overrun the surface cooler air in place...likely resulting in
a soaking rain for most areas. However...there are some concerns
with precipitation type. As the low approaches Monday night into
Tuesday...this will cause an upper-level ridge to build over New
England. That will allow for the surface high to our north to
strengthen. There will not be much in the way of cold air...but
there will be plenty of dry air ahead of the storm. Insitu cold
air damming may result in enough cold air late Monday night into
Tuesday for snow to occur. The best chance for snow will be across
the ridges. This will have to be monitored since uncertainty
remains high this far out. Any snow should change over to rain
Tuesday night as warmer air takes over with the primary low
passing by to our west.

The primary low will track into Canada Tuesday night while the
coastal low slowly moves off to the east. Rain will decrease in
coverage...but low clouds and fog will likely hang around. Weak
high pressure will settle overhead for Wednesday before a potent
cold approaches late in the week.


VFR conditions through at least Sunday PM if not Monday eve.
Scattered-broken stratocumulus deck at 4000-6000 feet will
continue with varying coverage into Saturday. This will eventually
be replaced by an increasing high cirrus deck by Sunday morning.
Clouds will lower and thicken Sunday night as a weakening system
moves through, along with the chance for some rain/snow showers. A
brief period of sub-VFR is possible.

Winds will be out of the west/northwest through Saturday, with
daytime gusts up to 20-25 knots.

VFR conditions are likely for Monday through Monday evening.
Clouds will increase and rain will overspread the areas late
Monday night into Tuesday. IFR conditions are likely for Tuesday
through Tuesday night.


Small Craft Advisory is in effect for all waters this afternoon
through Saturday for persistent gusty northwest flow with gusts in
excess of 20 knots. The period of strongest winds is expected
tonight into Saturday morning when winds may approach gale force
for a time.

Winds begin to decrease Saturday night, but SCA may need to be
extended with gusts up to 20 knots still possible. Winds finally
drop below SCA criteria Sunday.

High pressure will remain over the waters Monday into
Monday night. Coastal low pressure will develop late Monday night
into Tuesday near the Carolinas. The low will slowly track up the
coast Tuesday afternoon before moving off to our east Tuesday
night. A Small Craft Advisory will likely be needed for the waters
Tuesday through Tuesday night. High pressure may briefly build
toward the waters for Wednesday.


Meteorological autumn 2016 has ended (it runs from September 1st
through November 30th). It was unusually warm and dry across the
much of the area. Below are preliminary temperature and
precipitation rankings for this autumn.

Washington DC area (Ronald Reagan National Airport, DCA)
Temperature (warmest)     Precipitation (driest)
1.  63.9 degrees (2016)   1.  1.83 inches (1930)
2.  63.3 degrees (2007)   2.  2.42 inches (1941)
                          3.  2.65 inches (2001)
                          4.  3.33 inches (1998)
                          5.  3.45 inches (1879)
                          6.  4.07 inches (1967)
                          7.  4.16 inches (2016)
                          8.  4.26 inches (1973)
Records have been kept at DCA since August 1st 1941. Additional
temperature records in the Washington DC area date back to 1872,
and additional precipitation records date back to 1871.

Baltimore MD area (Baltimore-Washington International Thurgood
Marshall Airport, BWI)
Temperature (warmest)     Precipitation (driest)
1.  64.7 degrees (1931)   Not in Top 20 (2016 was 29th driest
2.  63.4 degrees (1941)   with 6.65 inches)
3.  63.3 degrees (1881)
4.  61.9 degrees (1946)
5.  61.8 degrees (1900)
6.  61.3 degrees (1970)
7.  61.1 degrees (1927)
8.  60.7 degrees (1947)*
9.  60.4 degrees (1930)
10. 60.3 degrees (1919)
    60.3 degrees (1945)
    60.3 degrees (1942)
13. 60.2 degrees (2016)
    60.2 degrees (1985)
*One day of missing data
Records have been kept at BWI since January 1st 1950. Additional
temperature records in the Baltimore MD area date back to 1872,
and additional precipitation records date back to 1871.

Dulles VA area (Washington Dulles International Airport, IAD)
Temperature (warmest)     Precipitation (driest)
1.  60.3 degrees (2007)   1.  3.96 inches (1998)
2.  60.0 degrees (2016)   2.  4.59 inches (1978)
3.  59.5 degrees (1985)   3.  4.61 inches (1965)
                          4.  4.97 inches (2016)
                          5.  5.31 inches (1981)
Records have been kept at IAD since November 30th 1962.


MARINE...Small Craft Advisory until 6 PM EST Saturday for ANZ530>543.


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