Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 32 33 34 35
FXUS61 KLWX 261857

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
257 PM EDT Wed Oct 26 2016

High pressure will continue to drift east from the area through
tonight. A cold front will cross the area Thursday evening. High
pressure then builds over the area through Friday night. A
secondary cold front crosses the area this weekend with high
pressure then into at least the middle of next week.


As of 2pm, a surface ridge axis extends from high pressure near
the ontario/quebec border to the MD part of the Chesapeake Bay.
Weak low pressure is over eastern IA. A light east or south wind
is over the area on the west side of the ridge. Winds will shift
south across the area through the night, though this progress will
depend on the movement of the ridge axis which may stall until
Thursday morning.

The progress is complicated by a warm front shifting east from
the eastern Great Lakes. Associated lift should cause some
sprinkles to push east along the Mason-Dixon line rest of this
afternoon into the evening. Should appreciable rain develop, then
an in-situ cold air damming wedge would develop. This would not be
overcome by south winds overnight and would be delayed well into

High clouds thicken and lower through tonight with temperatures
more mild than last. Expect inland locations to drop around 40F
and near shore areas to the mid 40s.


Low pressure develops as it moves east across the Upper Midwest
tonight and the eastern Great Lakes Thursday. The associated cold
front crosses the area Thursday evening with prefrontal rain
showers crossing the area from the west from the late morning to
the late afternoon. Likely PoPs were reserved for roughly north of
the Potomac River where greater convergence occurs into the
afternoon. Guidance consensus has activity developing/enhancing
east of I-95 in the late afternoon/early evening. This could
develop into a line with gusty showers for southern Maryland into
the evening hours. Expect generally a quarter inch QPF north of
the Potomac (maybe a tenth south) with perhaps half an inch for
southern MD.

Upslope rain showers look limited with likely PoPs decreasing to
chance from afternoon to evening.

Gusty winds accompany the cold front with an abrupt shift from
south to west. Magnitude is generally 20 mph with gusts to 30 mph.
Higher gusts possible in convective showers, particularly in
southern MD.

Max temps Thursday mid 50s along the Mason-Dixon, then low to mid
60s across the rest of the CWA. However, development of an in-situ
cold air damming tonight would result in lower temperatures,
particularly north.

Gusty NW winds diminish into Friday morning as 1025mb surface high
pressure builds directly overhead Friday evening. Temperatures
near normal with maxima around 60F and minima around 40F (inland).


Falling heights attempting to descend out of eastern Canada will be
competing with a building ridge over the southeastern United States
over the weekend and into much of next week. At the moment, it
appears the ridge to the south will win out. This will result in a
warmer and drier than normal pattern over the Mid-Atlantic.

Over time, the ridging to the south begins to slowly retreat
westward which may allow for falling heights and increasing
precipitation chances by the second half of next week.


VFR generally conditions prevail through the TAF period. However,
a warm front developing over PA tonight and a cold front
crossing Thursday evening brings a risk for showers and low
ceilings. A light onshore flow develops across the area tonight,
turning south and increasing with gusts around 20 knots Thursday
morning. West, then northwest winds are expected behind the cold
front. Showers may be gusty, around 30 knots particularly east
from I-95.

NW winds with gusts 20 knots into Friday morning before easing.
High pressure overhead Friday evening.

Mainly VFR expected over the weekend with southwesterly
flow around 10 knots Saturday becoming westerly behind a frontal
passage Saturday night into Sunday.


High pressure is just east of the area with a light east winds
developing. Wind shifts south overnight and increases ahead of a
cold front that crosses Thursday evening. SCA begins at 7am for
southern MD waters then expands at 10am for all waters with
southerly channeling of 20 to 25 knots. The northward progression
of winds may be slowed depending on the pressure pattern.

Likely showers late Thursday afternoon/evening associated with the
cold front. Strong gusts and special marine warnings possible
with the showers. Wind shifts W then NW behind the cold front
Thursday night with gusts around 25 kt into Friday morning.
Tranquil Friday evening under high pressure.

Southwesterly winds ahead of an approaching cold front
Saturday will likely result in Small Craft Advisory level wind gusts
over the waters. Winds should diminish by Sunday as the front stalls
over or just south of the waters.


Baltimore-Washington International Thurgood Marshall Airport
(BWI) near Baltimore MD dropped to 32 degrees this morning,
marking the first time since April 10th that the temperature has
dropped to freezing (low on April 10 was 26 degrees).

Washington Dulles International Airport (IAD) in northern Virginia
dropped to 30 degrees, which is the first time the temperature has
fallen below freezing there since April 14th (when the low was
31 degrees).

Ronald Reagan National Airport near Washington DC (DCA) was 41
degrees this morning. Its last day at or below freezing was 31
degrees on April 10.


MARINE...Small Craft Advisory from 10 AM Thursday to 6 AM EDT Friday
     for ANZ530>532-535-536-538>542.
     Small Craft Advisory from 7 AM Thursday to 6 AM EDT Friday for


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