Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 200803
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
403 AM EDT Fri Apr 20 2018

.SYNOPSIS...Strong high pressure over the Upper Midwest will
migrate eastward into the Northeast by Sunday before moving
offshore Monday. Low pressure will approach the area from the
southeast U.S. during the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

Mostly clear skies being observed early this morning with
temperatures falling in to the 30s to near 40 degrees across the
CWA. Winds have dropped off appreciably west of the metro areas as
the gradient relaxes between low pressure over Nova Scotia and high
pressure sliding its way south and east from the upper Midwest.
Couple the light winds and clear skies, this sets up prime
conditions for temperatures to drop near and below the freezing mark
this morning. A Freeze Warning remains in effect until 9am for
locations west of I-95, extending westward to the I-81 corridor.

As strong high pressure builds over the Great Lakes region today, we
will see winds pick back up as mixing increases later this morning.
Winds won`t be nearly as gusty as yesterday, but expect gusty
northwest breezes of 20 to 30 mph through this evening, before winds
subside. Temperatures through tonight will continue the below normal
trend, topping out today generally in the middle 50s to near 60
degrees, while the warmest locations across the Central Foothills
and the Northern Piedmont of Virginia will extend in to the 60s.
Lows tonight will fall back in to the 30s, but remain a touch warmer
than this morning. A Freeze Watch is in effect tonight for counties
surrounding the I-81 corridor, including portions of north central
Maryland and the Shenandoah Valley.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

The weather pattern this weekend will be dominated by the
aforementioned area of high pressure to our north, delivering dry
conditions, light winds, and slowly moderating, yet still below
normal temperatures for the middle of April. Expect some high to mid
level clouds to move overhead for the latter half of Saturday and
persisting into Sunday as a jet max and some mid level energy
crosses the northern portion of our CWA. Highs will range in the
lower to middle 60s, with lows bottoming out in the upper 30s to
lower 40s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...

Strong sfc high pressure over the Northeast Mon will move
offshore in the afternoon with an easterly flow developing late
Mon night resulting in low clouds with light rain or drizzle
along and west of the Blue Ridge. Stratiform rain will
overspread the area later Tue into Wed as easterly flow
strengthens detween departing high and sfc low lifting from the
Southeast into the Mid-Atlantic. The low will begin to move
away from the area during the second half of the week with a
gradual drying trend expected, but it won`t be completely dry.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...

VFR conditions prevailing through the weekend as high pressure
builds to our north. Gusty northwest winds expected to return this
morning as mixing commences, gusting to around 25 knots during the
day before abating late this afternoon and evening. Winds will
remain light through the weekend, mainly northerly on Saturday, then
veering to the northeast Sunday, then east southeast through Sunday
night.

MVFR conditions will begin to develop Mon night as easterly flow
develops. Widespread clouds with stratiform rain is expected Tue
into Wed with flight restrictions likely.

&&

.MARINE...

Small Craft conditions will continue today with gusty northwest
winds expected over the waters. Winds are forecast to subside this
evening as the pressure gradient relaxes and high pressure over the
Great Lakes wedges overhead. One exception to this will be the lower
Chesapeake, where winds will likely reach marginal SCA conditions
after midnight, continuing towards daybreak. With high pressure
dominating the weather pattern through the weekend, light northerly
winds are expected with no advisories or headlines anticipated.

&&

.FIRE WEATHER...

RH`s will drop below 30% today south of Fauquier county with
lowest Rh`s in Albermarle, Nelson, and Augusta counties. In this
area, the winds will be 10 kt or less. So, no SPS warranted.

&&

.TIDES/COASTAL FLOODING...

Early to middle of next week a decent east to southeast flow
will develop which will result in water levels rising. Would
expect minor coastal flooding in the Tue-Wed time frame.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Freeze Watch from late tonight through Saturday morning for
     MDZ003>006-507.
     Freeze Warning until 9 AM EDT this morning for MDZ003>006-
     503>508.
VA...Freeze Watch from late tonight through Saturday morning for
     VAZ025>031-507-508.
     Freeze Warning until 9 AM EDT this morning for VAZ025>031-
     036>040-050>053-055-056-501-502-505>508.
WV...Freeze Watch from late tonight through Saturday morning for
     WVZ051>053.
     Freeze Warning until 9 AM EDT this morning for WVZ051>053.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ530>543.
     Small Craft Advisory from 2 AM to 8 AM EDT Saturday for ANZ534-
     543.

&&

$$
SYNOPSIS...LFR
NEAR TERM...BKF
SHORT TERM...BKF
LONG TERM...LFR
AVIATION...BKF/LFR
MARINE...BKF/LFR
FIRE WEATHER...LFR
TIDES/COASTAL FLOODING...LFR



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