Area Forecast Discussion
Issued by NWS Sterling, VA

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980
FXUS61 KLWX 181849
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
249 PM EDT Tue Apr 18 2017

.SYNOPSIS...High pressure will build over the area through early
Wednesday. The next cold front will cross the area Friday
afternoon. High pressure builds over New England for the weekend
while low pressure moving in from the west will impact the Mid
Atlantic Sunday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...Clear through early this
evening, then clouds increase late tonight across southwest
zones with light rain developing due to low-level upslope flow
and overrunning. Clouds and rain spread northeastward to
northern VA by daybreak and across the rest of the area Wed
morning and afternoon as high pressure shifts offshore.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...Some
light rain is still possible in the evening with a lull/break
in precip late Wed night. Low clouds and fog are likely to
be the main issue late Wed night. Chances for showers and
t-storms increase Thu as instability builds and a lee-side trof
develops. Coverage is expected to remain scattered with low risk
of severe wx due to weak shear.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...

Cold front pushes towards the Mid-Atlantic, bringing scattered
showers on Friday. Conditions will be become drier behind the
front. High temperatures will be in the 70s and 80s, and lows
will reach the 40s and 50s.

Dry conditions continue into Saturday, maybe some showers over
higher elevations... and PoPs increase over our CWA Saturday night
as a low pressure system approaches from the west. High temperatures
will be in the 50s and 60s... low temperatures overnight in the 40s
and 50s.

Guidance is in disagreement with the track of this low pressure
between Sunday and Monday. GFS brings it slower and moving across
the Mid-Atlantic with PW over one inch, while the Euro moves it
faster and PW below one inch. Expecting dry conditions behind this
system.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...Clouds increase late
tonight with bkn-ovc035 cigs at KCHO and then at all other
terminals after 12Z Wed. Potential for MBFR/IFR cigs/vsbys late
Wed night into Thu morning. Risk of t-storms Thu afternoo and
early evening.

Showers possible on Friday as front pushes through our area.
Drier conditions expected on Saturday. Showers return Saturday
night into Sunday. Sub-VFR conditions possible at times, mainly
Friday and Sunday with wind gusts reaching up to 20 kt for parts
of this period.

&&

.MARINE...Possible SCA across the lower Bay and lower Potomac this
evening due to channelling of SE winds. Winds should diminish
overnight and remain below SCA through Thu. SCA then more likely
Thu night and Fri.

Showers possible on Friday as front pushes through our area.
Drier conditions expected on Saturday. Showers return Saturday
night into Sunday. Sub-VFR conditions possible at times, mainly
Friday and Sunday with wind gusts reaching up to 20 kt for parts
of this period.

&&

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

&&

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



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