Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
358 am EST Monday Dec 29 2014
Weak disturbances will ride along a cold front...mainly to our
south...today through Tuesday. High pressure will build into the eastern
half of the country for the second half of the week. Low pressure
is expected to affect the middle Atlantic region this weekend.
Near term /today and tonight/...
As of 08z...1055mb surface high is north of Calgary while an upper low is
over northern Quebec and an upper trough is over the intermountain west. A
weak cold front extends from a low east of Newfoundland to the
Carolinas. High pressure will build north of the County Warning Area today...with a
northeasterly flow of 10 miles per hour or so setting up. Rain currently along southern
periphery of County Warning Area (with patchy sprinkles/light rain up through the District of Columbia
metropolitan area) will continue to drift south through today. Reduced probability of precipitation
across the balt-wash metropolitan per recent hrrr runs and observed radar
trends. Rain will continue to be light with less than a tenth inch
quantitative precipitation forecast. Maximum temperatures low to middle 40s under persistent middle-level clouds.
Ely component will promote precipitation development for central Virginia Blue
Ridge and areas farther west. Colder air there will allow some snow
above about 2500 feet today...lowering to around 1000 feet tonight.
Expanded snowfall areas to include dusting/0.1 inch in the central
shen valley...still less than inch for ridges. Elsewhere dry and
cloudy...min temperatures upper 20s to low 30s (mid 30s for near shore).
Short term /Tuesday/...
Precipitation shifts south as 1030mb surface pressure shifts into the
County Warning Area. Light northerly flow and maximum temperatures upper 30s to low 40s under clearing
Long term /Tuesday night through Sunday/...
High pressure expeceted to build into the area for new yrs evening...so weather will
not be a problem Wednesday night or the 1st day of 2015. The high should
remain in control of middle Atlantic weather through the end of the weak. This will
allow temperatures to moderate - Thursday morning lows will mainly be in the
l20s...by Sat morning about ten degrees warmer. The same will be true west/
high temperatures - Thursday around 40...a50 Sat.
Low pressure will be influencing the eastern U.S. Over the weekend. There is
difference in the models as to the trjectory of the system - Euro
has it on a southern track while the GFS takes it into the eastern Great Lakes
alng west/ a cold fnt pushing onto the east CST. Obviously this will need
to resolved in the coming days. At this moment p-type looks to be
liquid. If temperatures are able to drop below freezing then freezing rain will need to be
considered but that is a long way away.
Looking at the hemispheric 500 mb pattern of both the GFS and
ecm...the coldest air looks to remain locked over Hudson Bay into next
weak. Jan 5-8 2014 saw extremely cold air in the County Warning Area and the issuance of
multiple wind chill advsries and warnings (actual wind chill of -11
at dca....blo -40 in the highlands). No repeat in 2015.
Aviation /08z Monday through Friday/...
VFR conds expeceted Tuesday night through Friday.
No probs expeceted Tuesday night through Friday on the waters.
District of Columbia...none.