Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 161907

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
307 PM EDT Tue May 16 2017

High pressure settle over Bermuda tonight and persist through
Saturday. A cold front will cross from the north Friday night.
The cold front will stall over the southern Mid-Atlantic
Saturday, before returning north as a warm front Sunday. A
stronger cold front looks to move east through the area Monday


As of 2pm, 1020mb surface high pressure center is drifting east
of Cape Hatteras. This high will drift east to Bermuda through
tonight and persist there at least through Saturday. A light
southerly flow has developed over the area with abundant
sunshine. Mid level clouds have pushed south from PA over
northern MD. Max temps low to mid 80s this afternoon.

High pressure will set up near Bermuda tonight. Continued
southerly flow will allow for a warming trend. 925mb temps were
13C this morning and are expected to be 23C Wednesday morning.
This will allow for low to mid 90s max temps Wednesday. Min
temps will be around 60F tonight and 5-10 degrees higher
Wednesday night. Heat index 2-4 degrees above the air
temperature can be expected through the afternoon with dewpoints
in the mid 60s.

Terrain and a weak pressure trough warrants isolated to widely
scattered thunderstorms for the northern Shenandoah Valley and
NE to northern MD Wednesday late afternoon into Wednesday night.


925mb temps around 22C Thursday morning and increasing clouds
from the west in the afternoon should mean a bit lower max
temps for Thursday except for areas NE of Baltimore which will
be about 90F both days. Chances for thunderstorms west of the
Blue Ridge with weak troughing ahead of a low over the Great


High pressure will briefly move over the area Tuesday. Two areas of
low pressure will cross the eastern U.S. Wednesday into Thursday,
one across New England and the other across the southeast. Right now
most guidance maintains these as two separate systems with little or
no phasing, but several recent GEFS members and the 00z ECMWF show
enough interaction between the two to bring more clouds and
precipitation closer to the area during the middle of the week.

A reinforcing shot of cold air will accompany high pressure at the
surface as it builds into the area late in the week. A warming trend
likely commences next weekend.


VFR conditions prevail through Thursday. A south flow will
will continue to be 5-10kt through Thursday. Patchy fog possible
late tonight with MVFR vsbys in fog prone areas just before
sunrise the main risk.

A south to southwest flow is expected Wednesday through Thursday
with gusts around 15 knots. VFR conditions are likely during
this time. An isolated thunderstorm cannot be ruled
out...especially across the western terminals during the
afternoon and evening hours each day. Even across these
areas...most places will end up dry.

A cold front will approach Friday before passing through Friday
night. A better chance for thunderstorms is expected during this


High pressure will continue to drift from Cape Hatteras this
evening and set up near Bermuda tonight through Saturday. A
south to southwest flow will slowly increase through the
midweek. Southerly channeling may cause winds to gust into SCA
criteria Wednesday night into Thursday and again Thursday night
into Friday.

A cold front will approach the waters Friday before passing
through Friday night. Thunderstorms are possible during this


Unusually hot conditions are expected Wednesday and Thursday.
Record heat is possible during this time. Below are the record
highs and high min temps for Wednesday through Thursday night...
May 17th and 18th.

Wednesday Record Highs:
DCA: 92 in 1974.
IAD: 89 in 1986.
BWI: 93 in 1896.

Thursday Record High Minimums:
DCA: 72 in 2015.
IAD: 68 in 2015.
BWI: 68 in 1900.

Thursday Record Highs:
DCA: 96 in 1877.
IAD: 91 in 1987.
BWI: 97 in 1962.




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