Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
357 am EST Thursday Dec 25 2014
Strong low pressure will move north from the northern Great Lakes
into Canada today. That is currently pushing a cold front through
our region. Mild southern high pressure will move in for the
end of the week. A weak cold front will push in from the northwest
Sunday. Then low pressure from the deep south will ride up along
that front and pass just south of US Monday. Colder high pressure
will follow for middle week.
Near term /until 6 PM this evening/...
Surface wind shift has made it through most of the County Warning Area...however showers
continue to stream ahead the sharp middle level trough axis. These have
generally been of the light variety as lower level dry air cuts into
them. Expect the showers to be mostly east of the County Warning Area by 8am. Will
also cancel the Wind Advisory early since the available observation have
been staying in the 20s for the past few hours.
Skies will gradually clear this morning east of the appalachian
crest...although some stratocu may linger through the
day...especially across the north. A breezy day is expected with cold air advection
and a downslope flow. Gusts will generally be in the 20s to around
30...although some higher gusts are possible in the higher
elevations. Some upslope rain/snow showers are possible in the
west...but previous forecast seem on track with chance probability of precipitation and
moisture thinning out by this afternoon. The air behind the front is
not exceptionally cool and high temperatures are still expected to
be above normal for the lower elevations.
Short term /6 PM this evening through Saturday/...
A tranquil and mild period is in store for the next couple of days
as trajectories remain of Pacific origin and upper level ridging
begins to build over the area. At the surface...high pressure will
expand out of the deep south and gradually slide off the Carolina
coast by Saturday. With the quickly exiting low...the gradient will
relax quickly and winds will not be noticeable after this evening.
Used a blend for temperatures...which will remain above normal for
this time of year...with highs in the 50s and lows around freezing
for most locales.
Long term /Saturday night through Wednesday/...
Sun and Monday...a cold front stalls over the area. Low pressure will
form along it to our SW and move east through the Carolinas or S Virginia
Monday into Monday night. Given the track of the low to our south and
colder air to our north...expect the rain snow line to be in our
area or in PA Monday into Monday night. Exactly where will have to be
refined...but of course better chances of seeing some snow as you go
northwest towards the Mason Dixon line and Appalachians. All of that should
clear out by Tuesday as a large airmass of cooler more seasonable air
pushes in behind the low and covers much of the nation.
Aviation /09z Thursday through Monday/...
Band of showers will move east of the terminals between 10 and 12z.
Any remaining lower ceilings will end with the exiting
showers...although VFR ceilings may last a few hours longer. VFR
conditions are then expected through the remainder of the taf period
as high pressure gradually builds in. Westerly winds will gust to
around 25-30kt today...diminishing with sunset.
VFR through Saturday. West winds gradually become south at less than
Weak front hanging up on the region with an area of low pressure
moving along it early next week should allow for at least MVFR
conditions sun and Monday with the poss of IFR Monday. Tuesday and Wednesday
VFR returns with cooler temperatures.
Showers will push east of the waters early this morning. Westerly
winds will increase and gust between 20-30 knots for much of the day.
While solidly Small Craft Advisory conditions...do not see strong enough winds to
warrant a Gale Warning. The winds will diminish this evening...then
remain below Small Craft Advisory levels through Saturday as high pressure builds
over the waters. No marine issues anticipated for the weekend
through early next week.
Anomalies have leveled off and should hold steady or slowly fall as
westerly winds take over. Given the current water level trends and
the fact the morning high tide is lower astronomically...do not
think there will be any more coastal flooding issues...but will
continue to monitor this morning. By the evening high tide...
anomalies should have decreased sufficiently to preclude flooding.
District of Columbia...none.
Marine...Small Craft Advisory until 5 PM EST this afternoon for