Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 230140
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
840 PM EST Wed Feb 22 2017

.SYNOPSIS...
High pressure will remain over the Atlantic through Friday. A
cold front will pass through the area on Saturday. High pressure
builds over the area during the early part of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
Surface high pressure has moved off the coast and it will remain
over the western Atlantic through tonight. A cutoff low in the
southern stream of the jet will continue to drop well to our
south during this time.

Southerly flow will continue tonight...bringing unusually mild
conditions. Increased moisture will result in clouds. Increased
low-level moisture will get trapped underneath the nocturnal
inversion...resulting in areas of low clouds and fog. Min temps
will range from the mid to upper 40s in the Shenandoah Valley
to the lower 50s in Washington DC into the Virginia Piedmont.
Min temps will be close to climo for max temps this time of
year.

Any low clouds and fog should burn off Thursday morning. Southerly
flow will continue around high pressure Thursday. Increased
sunshine and southerly flow will allow for even warmer
condtions...with many locations reaching the mid 70s. Leaned
toward the warmer side of guidance. A pressure trough will
develop from the heating...which may be the focal point for a
few showers and even a couple thunderstorms later Thursday
afternoon. Will carry slight chance to chance pops during this
time with the highest pops near the trough across eastern West
Virginia...extreme northern Virginia and western Maryland.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
A few popup showers Thursday evening will dissipate with the
loss of daytime heating. More unusually mild conditions are
expected due to southerly winds. Areas of low clouds and fog are
possible.

A cold front will approach from the west Friday into Friday
night. Southerly winds will continue during this time. Ridging
aloft is also expected ahead of the cold front. This will cause
more unusually warm conditions for Friday with max temps in the
mid to upper 70s across most locations. Friday night will turn
out dry and warm ahead of the cold front.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A cold front will push across the region Saturday before moving
offshore Saturday night. Increasing warmth and moisture during
the day will lead to showers and a couple of thunderstorms,
mainly during the afternoon. A few showers could linger Saturday
night.

High pressure will build into the region Saturday night through
Sunday night. Temperatures will be 15 to 20 degrees cooler
then what has been experienced recently.

As the high moves offshore Monday, a storm system will move
parallel to the Ohio Valley and push into the mid-Atlantic
later in the day. A chance of rain and snow showers are possible
with the storm system. If the storm tracks farther south, then
precipitation could become more of a light snow event.

The storm will move offshore Monday night as high pressure
builds in behind the storm system through Tuesday evening. Dry
and seasonably cool temperatures expected through the period.

The high will move northeast and offshore the New Jersey Coast
overnight Tuesday into early Wednesday. Some light rain could
move in from the southwest ahead of a warm front late at night
and early Wednesday.

A warm front should move north of the region Wednesday, as
showers and perhaps a rumble of thunder develop ahead of an
approaching cold front later Wednesday afternoon. Springlike-
temperatures could evolve in this warm sector of the storm
system.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR condtitions expected through this evening. Areas of low
clouds and fog will likely develop underneath the nocturnal
inversion overnight into early Thursday. Went with MVFR
condtitions in the forecast. However...a stratus deck around
5kft may inhibit some of low clouds and fog from developing and
this will have to be monitored this evening.

Southerly flow will continue later Thursday through Friday
night. Areas of low clouds and fog are possible during the
overnight hours. Otherwise...VFR conditions are expected.

SubVFR conditions possible with rain showers and a few
thunderstorms Saturday, mainly in the afternoon and evening.
Winds southwest becoming west-northwest 10 to 15 knots gusts 20
to 25 knots Saturday. VFR conditions Saturday night once rain
showers and thunderstorms pass to the east. Winds northwest 15
knots gusts 25 to 30 knots Saturday night through Sunday.

&&

.MARINE...
High pressure will remain off the coast through Friday night. A
southerly flow is expected during this time. The gradient may be
light enough for some areas to decouple tonight into Thursday
morning. With dewpoints being higher than the water
temps...areas of fog are possible during this time. Wind speeds
should remain below SCA criteria through Thursday night.

The gradient will stregthen ahead of a cold front Friday through
Friday night. Have gusts capped around 15 knots during this
time due to the relatively cooler waters...but a few gusts
around 20 knots cannot be ruled out because if mixing were to
occur there are winds strong enough aloft.

Small craft advisories likely Saturday through Sunday. Gale
warnings possible Saturday night into Sunday. Southwest winds
ahead of the cold front will turn to the northwest behind the
cold front Saturday night through Sunday. Gusts 25 to 30 knots
are likely with gusts around 35 to 40 knots possible.

&&

.CLIMATE...
Warmest Februaries (average temperature)

   DCA           BWI           IAD
1. 46.9 (1976)   44.0 (1976)   42.1 (1990)
2. 45.2 (1990)   43.9 (1949)   41.1 (1976)
3. 44.7 (1997)   43.3 (1890)   41.0 (1998)
4. 44.3 (2012)   42.7 (1932)   40.9 (2012)
5. 43.9 (1949)   42.6 (1909)   40.5 (1997)

Feb 2017 (through the 21st)

DCA: 45.1  BWI: 41.6   IAD: 42.1

Warmest Winters (Dec 1-Feb 28/29)
   DCA              BWI              IAD
1. 44.7 (1931-32)   45.3 (1931-32)   40.0 (2011-12)
2. 44.3 (1889-90)   44.4 (1889-90)   39.7 (2001-02)
3. 43.3 (2011-12)   42.4 (1948-49)   39.4 (1997-98)
4. 43.2 (2001-02)   41.9 (1949-50)   39.0 (2015-16)
5. 42.8 (1949-50)   41.3 (1879-80)   38.3 (1990-91)

Winter 2016-17 (through Feb 21)
DCA: 43.0   BWI: 39.6   IAD: 39.9


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
UPDATE...WOODY!
PREVIOUS...BJL/KLW/DFH


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