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Office: LWX

FXUS61 KLWX 220800

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Thu Mar 22 2018

Low pressure will move into the Canadian Maritimes today. High
pressure will build in from the west through Saturday. Low
pressure will move from the mid-Mississippi Valley Saturday to
the Carolinas Saturday night. High pressure will follow for the
beginning of next week..


The Nor'easter is located east of Long Island this morning and
continues to move away to the northeast. The light snow from
last evening has dissipated and clouds are beginning to break
up. A shortwave trough currently over the Ohio Valley will cross
the area today, so skies won't be completely clear. A seasonably
cold airmass will remain in place, and with northwest wind gusts
to 30 mph or so, it will feel chilly. High temperatures are only
expected to be in the 40s, perhaps reaching 50 in central VA.


The axis of high pressure centered near Hudson Bay will remain
west of the area tonight and Friday. Another vort max will be
crossing the area Friday, which could increase cloud cover at
times. The GFS is one of the "wetter" models, showing potential
for some light upslope snow showers and perhaps a sprinkle or
flurry east of the crest. Have kept the forecast dry for now
given relatively shallow moisture. There will remain enough
gradient for 20-30 mph gusts again on Friday as well. After
morning lows in the 20s, daytime highs will range from the lower
40s to lower 50s.

The surface ridge axis will reach the area Friday night,
resulting in lighter winds. Lows in the mid 20s will be common
outside of the cities, with some teens likely west of the Blue

Attention turns to the next storm system which will be
approaching from the mid-Mississippi Valley, which will dive
into the Carolinas by Saturday night. We will be on the cold
side of this system, and if any appreciable precipitation falls,
it would likely become snow. The northern gradient of the
precipitation is in question as strong high pressure will be
positioned to our north in Canada. It is becoming more likely
that our far southern tier of counties at a minimum could see
some snow. While accumulations would likely be highly elevation
dependent, some accumulations could occur in the valleys as well
if precipitation continues into the evening (which is quite
possible). Winter headlines may eventually need to be considered
when confidence becomes higher. Outside of precipitation, highs
should reach the 40s, with lows Saturday night back below


The disturbance across our southern and southwestern zones will
move away early Sunday. High pressure will gain control of the
region midday Sunday through Tuesday. Skies will be mostly sunny
each day and mainly clear each night. Temperatures will remain
nearly 10 degrees below average with highs in the middle 40s and
lows in the middle 20s.

The high is expected to move to the East Coast later Tuesday
into Tuesday night to allow for a slight southeasterly wind to
develop and thus, increasing clouds in our western zones and in
the Blue Ridge Mountains. We should remain dry through Tuesday,
then introduce a better chance for a rain or snow shower Tuesday
night with the upslope flow.

The high moves to the East Coast Wednesday to allow for a storm
system to move east across the Great Lakes region. An associated
cold front will drag across the Ohio Valley and mid-Atlantic region
Wednesday night then possibly stall across the mid-Atlantic region
Thursday. There is a chance of some rain and snow showers in our CWA
Wednesday night into Thursday along this front. Temperatures will
not be as cool Wednesday through Thursday.


Ceilings have lifted as low pressure continues to pull away and
the threat for linger flurries is over. VFR is then expected
through Friday, though cigs in stratocumulus are possible at
times. The main concern will be gusty northwest winds which
could gust above 25 knots during the daytime each day.

VFR conditions expected early Saturday, before another system
may affect us with wintry weather late Saturday into Saturday
night. Highest chance of sub-VFR is at CHO.

MVFR conditions remain possible at CHO with any snow showers
around early Sunday. Otherwise, VFR conditions at all terminals
Sunday through Monday night. Winds northeast 5 to 10 knots
Sunday through Monday, becoming southeast then shifting
northwest 5 to 10 knots Monday night.


While there is currently some lull in the winds, SCA conditions
will return quickly today. There will be some diminishing of the
winds on the tidal Potomac tonight, but then SCA will return for
all waters during the day on Friday. Winds should diminish
Friday night into Saturday as high pressure builds across the
area. Weak low pressure will pass by to the south Saturday

No marine hazards expected Sunday through Monday night. Winds
northeast around 10 knots Sunday through Monday, becoming
southeast 10 knots then shifting northwest 10 knots Monday


Current water levels above one foot will still result in minor
tidal flooding at Straits Point this morning. As coastal low
pressure continues to lift to the northeast, the northwest winds
will be able to win out today and drive water levels down.


MD...Coastal Flood Advisory until 9 AM EDT this morning for MDZ017.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ531>534-537-
     Small Craft Advisory until midnight EDT tonight for ANZ530-535-