Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
919 am EST Wednesday Dec 11 2013
a reinforcing cold front will move through the area this
evening. Arctic high pressure will build overhead through the end
of the week. Low pressure will impact the region this weekend.
Near term /through Thursday/...
high pressure will remain over the region today...bringing dry
conditions along with sunshine. A weak cold front will approach
from the west this afternoon and it will result in a few clouds
mainly across northern Maryland and the Potomac Highlands. Maximum
temperatures will remain below climatology...despite the sunshine. Maximum temperatures
will range from the 20s in the mountains to the lower 40s in
central Virginia and southern Maryland.
The weak cold front will pass through the region tonight and a
pressure surge behind the front will cause winds to increase
overnight. Northwest winds will gust around 15 to 20 miles per hour behind
the cold front and ahead of building Arctic high pressure. Min
temperatures will be quite cold tonight...ranging from the single digits
in the mountains to the teens across most other locations. The
combination blustery conditions and cold temperatures will cause low wind
chills overnight. Wind chill values will dip below zero in the
mountains and into the single digits and lower teens across most
Short term /Thursday night through Friday night/...
high pressure builds across the area Thursday night into early
Friday...then moves offshore Friday afternoon. With high pressure
overhead...clear skies and light winds Thursday night is expected to
be cold with lower to middle 20s in downtown District of Columbia/Baltimore and teens in
the suburbs. Return flow/sunshine will help to moderate
temperatures some on Friday...but still expect below normal
A weak backdoor front approaches from the north Friday night but
likely dissipates before passing through the County Warning Area. Models show warm
advection ahead of the next low pressure system for
increasing/thickening and eventually lowering clouds Friday night.
Light precipitation in the form of snow may also start to break out late
at night over the Potomac Highlands/central Shenandoah Valley.
Long term /Saturday through Tuesday/...
high pressure builds to the north on Saturday...wedging down into
the middle Atlantic. Meanwhile...energy over Texas on Friday ejects
east into the Tennessee Valley/southeast states on Saturday.
Models show multiple low centers...the dominant one likely
eventually moving up the coast.
Confidence is high that the storm will bring precipitation to the area
Saturday into Saturday night /thus categorical pops/...but there is
uncertainty regarding temperatures and thus p-types during the
Most guidance supports p-type as mainly snow at the onset Saturday
morning...but most guidance also leans toward temperatures warming
for a rain/snow mix later Saturday or even just rain across the
southeast portion of the County Warning Area. With cold wedge in place...would tend
to favor a colder solution and/or slower warming /at least at the
surface/. Will obviously need to fine tune p-type changes as we get
closer to the event.
Some precipitation may linger into early Sunday...then as the low moves
northeast County Warning Area should dry out for the rest of Sunday except for
upslope snow showers.
High pressure builds in early next week. Temperatures may be colder
than what mex suggests and forecast reflects this.
Aviation /14z Wednesday through Sunday/...
VFR conditions expected today and tonight. A frontal passage will cross the
region tonight bringing winds back out of the northwest through
High pressure builds in to end the week. Low pressure will likely
bring a wintry mix Saturday into Saturday night.
high pressure will approach the waters today before a frontal passage
crosses late tonight. Northwest winds increase and a Small Craft Advisory is in effect
late tonight through Thursday afternoon.
Marginal Small Craft Advisory winds could linger over the Lower Bay into Thursday
evening...otherwise diminishing winds are expected overnight
Thursday into Friday as high pressure builds in. Winds will increase
again Saturday/Saturday night as low pressure approaches...likely
into Small Craft Advisory range Sunday as the low departs.
District of Columbia...none.
Marine...Small Craft Advisory from midnight tonight to 6 PM EST
Thursday for anz530>543.