Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 221429
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1029 AM EDT Wed Mar 22 2017

.SYNOPSIS...
High pressure will return across the area this afternoon, and
remain through Thursday night. A warm front will cross the
region Friday. Low pressure may affect the area Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The cold front crossed the area earlier this morning, with a
surge of northwest winds and a 10-15 degree temperature drop. At
this point, cold advection and diurnal/compressional warming
should come close to cancelling each other out. Temps should
remain somewhat steady through the afternoon. In addition, the
gustiest winds should continue into early afternoon before the
cold advection/pressure gradient relaxes.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
High pressure will continue to build south tonight, allowing
winds to diminish. The center of the high will be centered over
PA by Thursday morning. Western valleys will likely decouple,
leading to lows in the teens, with 20s elsewhere. The chilly
airmass will remain in place for Thursday, with highs once again
remaining in the 40s.

Thursday night into Friday morning forecast is a bit tricky, as
it will start out mostly clear, which will likely allow
temperatures to drop to near freezing. Isentropic ascent
increases late with next warm surge aloft. ECMWF continues to be
farther south with QPF compared to NAM/GFS, although it does
have support of some GEFS members. If this solution were to
occur, a brief period of freezing rain/and or sleet could occur
in the northern quarter of the area, but confidence is very low.
Temperatures will quickly warm above freezing though with
established southerly flow, reaching the 50s and 60s by Friday
afternoon.

The area will remain in the warm sector of a low pressure
system in the Plains on Friday night, with mostly cloudy and
mild conditions expected.
&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Reasonable agreement in the long term. The entire region should
feel a warm southwest flow Saturday as high pressure to the
east pumps warmer and more humid gulf air northward.
Temperatures should reach the 70s in most of the area. It should
stay dry with forcing from fronts and storms keeping their
distance.

Backdoor cold front may slip south into the area, especially in
MD, Saturday night and Sunday, preventing the second day of the
weekend from being as pleasantly warm as the first. Add in the
approaching system to the west, and Sunday also looks wetter
than Saturday, with showers or perhaps a thunderstorm possible.

The front may push back north as a warm front later on Monday,
as the storm moves eastward into the Atlantic, with a better
chance at 70s returning to the region. However, the chance of
showers or even a thunderstorm will remain as the system pushes
off the coast.

By Tuesday, guidance is uncertain, with potential for the front
to drop back south and another low to move east into the region.
Showers and cooler weather look possible.
&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will remain through the TAF period. Peak gusts
of 30-35 kt will still be possible until noonish, with slightly
lower gusts persisting through afternoon. Winds will diminish
tonight as high pressure builds in from the north. No issues
expected through Thursday evening with the high in control. At
this time, light precipitation Friday morning is likely to stay
north of the terminals. Southerly flow could be a bit gusty
Friday afternoon. VFR conditions expected through Saturday night
although clouds will be prevalent.

VFR Saturday. Sub-VFR again possible with rain Saturday night
into Sunday. Winds becoming south Friday, perhaps a few gusts to
20 knots, continuing Saturday, then becoming more uncertain
Sunday.

&&

.MARINE...
Winds are on the cusp of gales at this time. Am keeping the
Gale Warning for all waters til noon. A Small Craft Advisory
will be in effect thereafter (afternoon-evening) as winds
decrease. Will have to monitor in case gales continue a bit
longer.

Lighter winds are expected Thursday and Thursday night as the
high moves overhead and then offshore. SCA conditions in
southerly flow will be possible Friday.

Winds mainly sub-SCA Saturday and Sunday.
&&

.FIRE WEATHER...
Dry conditions and gusty winds expected today following strong
cold frontal passage. Relative humidities will drop into the
15-30% range with sustained north to northwest winds from 15 to
20 mph, gusting 30 to 35 mph. However, following recent rain and
snow, fuel moistures are currently between 9 and 15 percent,
and thus fire weather statements are not needed at this time.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from noon today to 8 PM EDT this evening
     for ANZ530-531-535-536-538>540.
     Gale Warning until noon EDT today for ANZ530>543.
     Small Craft Advisory from noon today to 4 AM EDT Thursday for
     ANZ532>534-537-541>543.

&&

$$
SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...ADS
LONG TERM...RCM
AVIATION...HTS/ADS/RCM
MARINE...HTS/ADS/RCM
FIRE WEATHER...ADS



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