Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 200721

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
321 AM EDT Thu Apr 20 2017


High pressure off the coast will move further east today.  A
cold front will drop into the Mid Atlantic Friday afternoon.
Weak high pressure builds over the area Friday night before
low pressure impacts the area Saturday night and Sunday.



Have cut back on PoPs for the first half of today. A warm front
extends from low pressure over IA over MI and into the northeast
US. Showers can be seen on regional radar across PA but these
are not making any southward progress. The potential exists for
showers/thunderstorms this afternoon. Coverage would be
scattered. Expecting quite a bit of cloud coverage today. This
will limit CAPE, and hodographs show only weak shear.

Highs around 80.



Boundary appears to be hanging around right into the weekend.
This will lead to extensive cloud cover from Thursday night
right through Saturday. The better chance for rain looks to be
during Saturday as low pressure forms over the TN Valley and
progresses east during the late afternoon.

Highs look to reach the low 80s over much of the area Friday,
but with the extensive cloud cover/rain Saturday highs will only
reach climb to the low/mid 60s.



Unsettled weather looking likely for much of the weekend and into
next week.

An area of low pressure will move from the lower Mississippi River
Valley Saturday to the Mid-Atlantic/Southeast coastline by Sunday,
tracking eastward along a baroclinic zone. There remains some
discrepancies between model suites as to how far north/south the
zone becomes established and therefore the low track and area of
steadiest/heaviest rainfall, but the setup should be favorable for a
period of overrunning rain Saturday into Sunday.

Energy will likely be slow to depart the east coast in the
Monday/Tuesday timeframe, and with low pressure possibly lingering
offshore as high pressure builds into New England, this may promote
onshore flow, cool temperatures, lingering clouds and chances for

By Wednesday, should see more of a southerly flow develop as a low
pressure system moves through the Great Lakes. This should bring
warmer temperatures, as well as the possibility for additional
showers, especially west.

Temperatures will be on the cooler side in the extended period, with
highs likely holding in the 50s for much of the region Sunday with
rain/clouds. Some improvement Monday/Tuesday, with highs generally
in the 60s. Warmest day looks to Wednesday where 70s likely. Lows
during this time period mainly 40s to around 50F.



Currently across the northern part of the forecast area ceilings
are in the 010-015 range while CHO is over FL 100. Believe
ceilings will lower further south as the morning progresses
while at the major airports MVFR will be the predominant

Improvement is expected during Friday but then degrading by
Saturday afternoon.

Low clouds and periods of rain Saturday night and Sunday will likely
bring widespread sub-VFR reductions to both ceilings and
visibilities. Low clouds and areas of light showers may persist into
early next week.



Winds remaining below SCA values today/tonight. Rain is expected
for the waters Saturday.

Generally sub-SCA conditions expected Saturday night and Sunday. SCA
conditions possible Monday with increasing northeasterly flow.



Water levels will continue to be elevated today. Departures
will be running about a foot above normal. Some Action Stages
will be threatened.




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