Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1018 am EST Friday Dec 19 2014
high pressure will build overhead this afternoon...then persist
through Sunday. Low pressure will track up the middle-Atlantic coast
Monday through Monday night. A strong cold front will pass through
the area Wednesday.
Near term /through tonight/...
an upper-level disturbance will continue to move away from the
area this afternoon while surface high pressure builds in from the
Ohio Valley. A northwest flow ahead of the high will cause
seasonably chilly conditions during this time.
A broken/overcast stratocu deck remains across the northern and central
portions of the County Warning Area this morning. This is because moisture remains
trapped underneath the subsidence inversion. Cold advection should
cause enough instability for the cloud deck to hang around...but
there will be breaks of sunshine this afternoon as drier air moves
in from the northwest. Further south across central
Virginia...plenty of sunshine is expected due to the downsloping
High pressure will build overhead tonight. The strato cumulus deck
should break across most areas this evening...but high and middle-
level clouds will increase from southwest to northeast later
tonight as an upper-level disturbance approaches from the
Tennessee Valley. Min temperatures will range from the lower 20s in the
mountains to the lower and middle 30s in downtown Washington and
Short term /Saturday through Sunday/...
a pair of shortwaves will approach on Saturday then exit off the
coast Saturday night. Northern stream is moisture starved and will
not phase with the southern stream one. In addition...quantitative precipitation forecast associated
with the southern stream one looks mainly south of the County Warning Area. Light
precipitation may brush the southwest tier /Highland County to Albemarle
County/...otherwise County Warning Area will be dry with some clouds. Followed
blend of srefs/mav for maxima and srefs/met for minima.
High pressure builds north of the area on Sunday. Should be some
sunshine with temperatures around climatology.
Long term /Sunday night through Thursday/...
somewhat of a wedge develops Sunday night into Monday. Meanwhile...southern
stream wave leads to low pressure development along/off the
southeast coast. Result will be increasing clouds Sunday night
then the likelihood of precipitation Monday. Much of the precipitation
looks to be liquid but if it arrives early enough Monday then the
event may begin as a wintry mix.
This would exit Monday night but models show a significant trough
affecting the middle-Atlantic through mid-week. Followed latest wpc
grids with fairly high probability of precipitation Tuesday through Wednesday...p-type
mostly in the form of rain.
Aviation /15z Friday through Tuesday/...
a broken stratocu deck is expected across most of the terminals
through this afternoon. Ceilings should remain above 3kft. Northwest
winds will gust around 15 to 20 knots through this afternoon
before diminishing around sunset. High pressure will build over
the terminals tonight. VFR conditions will continue.
VFR expected through Sunday. Potential exists for flight
restrictions late Sunday night into Monday as wedge sets up and wave
of low pressure brings precipitation.
northwest winds will continue today as high pressure approaches from the
west. A Small Craft Advisory is in effect for the waters during
this time. High pressure moves overhead tonight and winds should
subside by evening.
Generally sub-Small Craft Advisory conditions expected into early next week.
District of Columbia...none.
Marine...Small Craft Advisory until 5 PM EST this afternoon for