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Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
249 PM EST Thursday Feb 26 2015

a cold front will pass through the region tonight and high
pressure will build overhead Friday through Saturday. The high
will move off the coast Sunday and another cold front will pass
through the area Monday. Low pressure will likely impact the area
Tuesday and Wednesday of next week.


Near term /through tonight/...
low pressure moving quickly east offshore of the Delaware-Maryland-Virginia this
afternoon. Some breaks in the clouds are allowing temperatures to pop above

Attention turns to northern stream energy/cold front which is now
pushing through western PA with some light snow. Fairly good
agreement with some of this snow making it past the appalachian
crest late this afternoon...spreading toward the I-81 corridor this
evening. Have raised probability of precipitation to likely across a larger portion of
eastern WV/western Maryland...and these may have to be adjusted upward
farther east. However...less certainty of how far snow showers
survive with various depictions in quantitative precipitation forecast/sim reference fields...therefore
decreasing probability of precipitation with eastward extent. Should the snow reach the
metropolitan would be around midnight or shortly thereafter.
Accumulations would likely be a half inch or less. An exception is
in the upslope regions which will benefit from the cold moist
airmass...but even there contributions from the Great Lakes are
little to none and will limit amounts. These amounts may still be
enough to coat roads as temperatures cool after sunset.

Some spread in guidance in regards to low temperatures tonight. Snow
pack...clouds (which should increase again with the front)...and
wind (light but perhaps not calm everywhere) could have
contributions. Raised slightly over previous forecast but still on
the cooler side of the envelope.


Short term /Friday through Friday night/...
Canadian high pressure will build toward the region behind a
departing cold front for Friday. Northwest winds will usher in
more bitterly cold conditions. A few flurries cannot be ruled
out...but there should be enough dry air and subsidence ahead of
the high to prevent any snow accumulation. Maximum temperatures will range
from the lower teens in the mountains to the lower and middle 30s
in central Virginia. The forecast leans toward the colder
guidance...despite a downsloping flow and some sunshine due the
strong cold advection that will be taking place.

High pressure will build overhead Friday night. Mainly clear
skies...light winds and dry air will allow for radiational
cooling. Therefore...Friday night will turn out quite cold. Leaned
toward the colder side of guidance due to the radiational cooling.
Min temperatures will range from below zero in the Allegheny the single digits across most other
the teens in Washington and Baltimore.


Long term /Saturday through Thursday/...
Canadian high pressure will remain over the region
Saturday through Saturday night...bringing dry and cold
conditions. High pressure will move off the coast Sunday and a
cold front will approach from the west. A southerly flow will
develop ahead of the cold front...allowing for warm and moist air
to overrun the surface cold air in place. This may trigger some
precipitation...especially Sunday afternoon into Sunday night. A
wintry mix is possible during this time...but certainty remains

The cold front will pass through late Sunday night into
Monday. High pressure will build in behind this system for later
Monday and Monday night...bringing dry and chilly conditions. Low
pressure will likely impact the area Tuesday into Wednesday.
Details remain uncertain at this time...but given the synoptic
setup it appears that warmer air will be drawn into this system.
The strong subtropical ridge over the southeast Continental U.S. Will likely
cause the track of the low to be to our west. Therefore...the
main ptype will be rain or a wintry mix changing to rain
depending on how much cold air remains on the front side of the
storm. The cold front with the low should pass through Wednesday
night and high pressure will return for the latter portion of next


Aviation /19z Thursday through Tuesday/...
breaks in cloud cover allowing a return to VFR conditions this
afternoon as low pressure moves offshore. Clouds will increase again
this evening ahead of a cold front. Ceiling heights a little uncertain
but MVFR seems reasonable. Light shsn will be possible at all the
terminals this evening into tonight...although mrb has the highest
chance. Uncertain how well they survive to the east. Have a period
of MVFR timed into the tafs...although cannot rule out brief IFR.

Ceilings may linger through much of Friday with abundant low level
moisture...but think they will eventually lift into VFR range. There
is a chance of flurries Friday afternoon. Northwest winds will range from
10-20 knots during the daylight hours.

High pressure will build over the terminals Friday through
Saturday night...bringing VFR conditions. Northwest winds will
gust around 15 to 20 knots Friday. A few flurries cannot be ruled
out Friday...but most of the time will be dry.

A cold front will approach the terminals Sunday into Sunday night.
A period of rain or wintry precipitation is possible during this
time. High pressure will return for Monday...but low pressure will
likely impact the terminals during the middle portion of next


occasional gusts to Small Craft Advisory levels will continue this afternoon as low
pressure moves offshore. Winds will diminish this evening. There is
a chance of snow showers as a cold front moves through late tonight
and shifts winds to the northwest.

High pressure will build toward the waters Friday behind a
departing cold front. Northwest winds are expected and a Small
Craft Advisory is in effect for the waters during this time. The
Small Craft Advisory continues Friday night for the Maryland
Chesapeake Bay and lower tidal Potomac River.

High pressure will build over the waters Saturday into Saturday
night before moving off the coast Sunday. A Small Craft Advisory
may be needed for portions of the waters Sunday night as a cold
front swings through. High pressure will return for Monday...but
low pressure will likely impact the waters during the middle
portion of next week.


Lwx watches/warnings/advisories...
District of Columbia...none.
Marine...Small Craft Advisory until 8 PM EST this evening for
Small Craft Advisory from 9 am Friday to 6 am EST Saturday for
Small Craft Advisory from 9 am to 6 PM EST Friday for anz535-
Small Craft Advisory until 4 PM EST this afternoon for anz535-


short term...bjl
long term...bjl

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