Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

000
FXUS61 KLWX 220221 AAA
AFDLWX

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
921 PM EST Wed Feb 21 2018

.SYNOPSIS...
A cold front will pass through this evening before stalling out
to our south Thursday. The boundary may return north as a warm
front Saturday before a stronger cold front passes through from
the west on Sunday. High pressure will return for early next
week.

&&

.NEAR TERM /THROUGH THURSDAY/...

Cdfnt is currently moving across the area this evening and
extends from BWI swwd through near Dulles and New Market, VA.
Temps and dewpoints are in the 70s/60s respectively south of the
front and mid 60s/mid 50s north of the front under a northerly
wind. Only a few showers are expected along the front this
evening as it continues to push south of the area. By 06Z, front
should have cleared the entire fcst area except perhaps Nelson
county where it will get hung up. Really, not a lot of shower
activity expected until very late tonight (after ~09Z or so)
when some shortwave energy will approach the Appalachians.

By this time tomorrow, temperatures will be more than 30
degrees colder than at present, with some places perhaps nearly
40 degrees lower.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
Wave of low pressure passes northeast along the stalled front on
Thursday night, with rain diminishing, but drizzle will linger.
We still have a small threat of freezing rain later at night
across northern portions of the region, particularly western
Maryland, depending on how much cold air can build south across
the region.

Another wave of low pressure will develop in Texas and move
northeast along the front early Friday, with another round of
rain expected in the morning. By afternoon, this wave should be
north of the region, and it will just be cloudy and drizzly
again. Temperatures should warm a bit, perhaps reaching the low
50s late.

Warm front aloft pushes north Friday night, but the surface
front will be stuck to our south thanks to the high to the
northeast providing a low level cold air wedge, so it will
remain relatively cool and drizzly. However, temperatures should
be steady or slowly rising as the cold air gradually erodes.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A frontal boundary will be stalled over our area on Saturday
separating a colder air mass from warm air. The boundary will
lift as a warm front Saturday night while a cold front moves
through on Sunday. These will allow for rain showers over our
area from Saturday into Sunday. Conditions should be drying out
Sunday night and remain dry through Wednesday as high pressure
builds in from the west and then settles overhead.

Temperatures will be above normal Saturday and Sunday and then
gradually become more normal by mid-week.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As a cold front continues to cross the region this evening, a
few showers will be possible. Winds will turn northerly behind
the front, and low ceilings with MVFR conditions are forecast
develop by early Thursday morning. MVFR/IFR conditions are then
likely in low clouds, areas of rain, and drizzle Thursday,
Thursday night, and potentially lasting into Friday.

Sub-VFR conditions possible Saturday into Sunday with a frontal
boundary affecting our area. VFR conditions should return on
Monday with high pressure building over us.

&&

.MARINE...
With warm air temperatures expected over considerably cooler
waters, the strongest gusts will likely be observed along the
shorelines. As a cold front crosses the region tonight, winds
will turn northerly behind the front, and now look more likely
to reach SCA criteria, so have raised one for the bay and
adjacent waters (except the Potomac) for after midnight.
Northeast flow looks to remain elevated on Thursday, so maintain
SCA thru the day. It may need additional extension into the
evening, but at this point am not confident about this so have
cut it off at the end of the day. As the front starts a gradual
retreat back to the north on Friday, winds should diminish below
SCA.

Winds are expected to remain below SCA criteria on Saturday.
Sunday winds will increase and come close to criteria, so it
should be monitored in case a SCA is needed. Winds will decrease
on Sunday night and remain below criteria into Monday.

&&

.CLIMATE...
The all-time February highest minimums are:
61 at DCA/Washington (2/17/1891)
58 at BWI/Baltimore (2/17/1891)
55 at IAD/Dulles (2/17/1976)
- records only go back to 1960 at IAD

The all-time February highest maximums are:
84 at DCA/Washington (2/25/1930)
83 at BWI/Baltimore (2/25/1930)
79 at IAD/Dulles (2/24/1985 and 2/25/2000)
- records only go back to 1960 at IAD

Record warm daily maximum temperatures
       Wed 2/21
DCA    75 (1953)
BWI    74 (1930)
IAD    70 (1997)

Record warm daily minimum temperatures
       Wed 2/21
DCA    51 (1954)
BWI    49 (1981)
IAD    45 (1981)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EST Thursday for ANZ530>534-
     537>543.

&&

$$
SYNOPSIS...RCM
NEAR TERM...LFR
SHORT TERM...RCM
LONG TERM...IMR
AVIATION...IMR/RCM
MARINE...IMR/RCM
CLIMATE...LWX



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.