Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
1009 am EST Thursday Dec 25 2014

Synopsis...
mild southern high pressure will build this afternoon through
Friday morning...before moving offshore on Saturday. 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/...
the back edge of thick clouds associated west/ cold front exiting the tip of
southern Maryland at this time. However...a stcu field associated west/ middle-level trough axis
currently spreading eastward. Lapse rates will be slightly better west of
the blurdg...and perhaps there will be a pinch more support across northern
Maryland. These areas will be a bit cloudier during the midday. By middle
afternoon...subsidence will assist in thinning cloud deck.

Latest guidance continues going forecast in terms of the wind forecast. Momentum in
column should be sufficient for occasional 30 knots gusts...a bit higher in the
mountains clouds will interfere in the process. Temperature forecast on track too
based on 12z radiosonde observations and latest lamp.

Source region not that cold and traj wont be crossing Great Lakes...so
theres not a lot of moisture for upslope precipitation. Even if there were...ekn
temperature at 38f suggests they wudnt all be shsn anyway. Will continue forecast
for chance probability of precipitation and rasn mix. No accums.

&&

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 /15z Thursday through Monday/...
VFR conditions through valid 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
10 knots.

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.

&&

Marine...
westerly winds will increase and gust between 20-30 knots for much
of the day. On the whole...guidance suggests that momentum Transfer
wont be capable of glw. However if ideal conds realized...then there
will be a small window of opportunity within a cpl hours of noon for
northern waters. Have opted to cap winds at 30 knots at this time. Will monitor
situation.

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.

&&

Tides/coastal flooding...
anomalies near 1 feet and dropping as westerly winds take over.
Given the current water level trends and the fact the morning high
tide is lower astronomically...there have been no issues with this
morning tide cycle. Even caution stage hasnt been exceeded thus
far. By the evening high tide... anomalies should have decreased
sufficiently to preclude flooding.
&&

Equipment...
temporary repairs have been made to klwx 88d. However...two
additional parts are on emergency order. They will be replaced
once they arrive on Friday. While the radar is operating at this
moment...it should still be considered unstable until the permanent
fix has been made.
&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...Small Craft Advisory until 5 PM EST this afternoon for
anz530>543.

&&

$$
Synopsis...hts/cas
near term...heights
short term...ads
long term...cas
aviation...hts/ads/cas
marine...hts/ads/cas
tides/coastal flooding...hts/ads
equipment...heights

National Weather Service Glossary of Abbreviations