Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 190113
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
913 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/...
A pressure surge will continue across the Mid-Atlantic region
this evening as high pressure over northern New England moves
southwestward. SE winds have increased to 10-15 mph with gusts
20-25 mph this evening. Clouds will increase late tonight as
warm air advection occurs aloft. Light rain is expected to
develop across the mountains west of the Blue Ridge and
progress eastward Wed morning. Coverage remains in question as
most guidance keeps light rain west and south of
Baltimore/Washington metros through Wed afternoon. Cant rule
out a passing shower as high pressure moves eastward.


&&

.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 /01Z WEDNESDAY THROUGH SUNDAY/...
SE winds expected this evening with gusts up to 20 kts through
midnight. Winds will slowly decline into Wed morning. Clouds
increase late tonight with bkn- ovc035 cigs at KCHO and then at
all other terminals after 12Z Wed. Potential for MVFR/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...
A pressure surge across the region has led to an increase in SE
winds on all the waters. A SCA is in effect through 2 AM. Winds
are expected to diminish into Wed morning however will need to
monitor closely as SCA may need to be extended into the early
morning hours.

Winds should 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.

&&

.TIDES/COASTAL FLOODING...
An onshore flow will continue through Wednesday. A pressure surge
has caused the onshore flow to strengthen this evening. This has
caused tidal anomalies to jump to between one-half and one-foot
above normal. These anomalies should remain in place through
Wednesday...which will cause water levels to approach minor flooding
thresholds near high tide. Did not go with an advisory at this time
with the latest forecast keeping water levels just below these
thresholds. This is because the onshore flow may weaken a bit
overnight into Wednesday behind the pressure surge.
However...confidence is low and the anomalies will have to be
monitored overnight.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Wednesday for ANZ530>543.

&&

$$
SYNOPSIS...LFR
NEAR TERM...HSK/LFR
SHORT TERM...LFR
LONG TERM...IMR
AVIATION...HSK/IMR/LFR
MARINE...HSK/IMR/LFR
TIDES/COASTAL FLOODING...BJL



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