Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Baltimore Maryland/Washington District of Columbia
946 PM EDT Tuesday Oct 13 2015
high pressure will build overhead tonight through Thursday. A
cold front will pass through the area Friday. Canadian high
pressure will build overhead this weekend.
Near term /until 6 am Wednesday morning/...
cold front has cleared all of the area xcpt St. Marys County.
Pressure surge coming in behind the front resulting in 28kt gusts
at Leesburg. This should last no more than 3 hours with winds
diminishing overnight. Only partial clearing expected in the north
overnight with skies becoming clear over the southern half of the forecast
area. Stratocu redevelops tomorrow with daytime heating and shortwave-
trough and cool pocket aloft move across.
Short term /6 am Wednesday morning through Thursday night/...
this aftn's National satellite img shows what lies ahead for the east...as
aftr the upper low moves away there are no clouds from WI to Washington. High
pressure will build into the Ohio Valley Wednesday before settling
overhead Thursday into Thursday night. It will be breezy Wednesday
with winds gusting around 20 to 25 miles per hour. There may be scattered/broken cumulus
deck as a weak upper-level trough remains overhead. Highs in the
60s Wednesday and Thursday...lows in the 40s xcpt u30s in The Highlands.
Long term /Friday through Tuesday/...
a dry cold fnt looks to mv through the area Friday. Any precipitation that does
form will quickly end by Friday night...with broad high pressure
building in for the weekend.
Dry weather for the weekend...with well below normal temperatures...and
frost/freeze potential is the big story. Strong surge of cold air advection over
the area as the high builds in...with the northern stream trough
dipping well south of the area. While there still remains some
differences in the temperatures...with the GFS on the cooler side than
the European model (ecmwf)...the agreement is there of seeing 850mb temperatures dropping
below 0 degrees celsius.
Lows Friday night still predominately in the 40s...with spots in the west
hitting the middle 30s. With light winds and clear skies...strong
radiational cooling should lead to most of the area seeing sub-40
Sat and sun nights...with a good portion of the Potomac Highlands
dipping to near or below freezing. We'll continue to monitor with
the potential for frost/freeze products. Highs Sat and sun will
hover in the 50s.
Ridging building in from the west late in the weekend will nudge the
trough on east...allowing for a warm up to start the week. High
pressure dominating the region keeps things dry and quiet.
Aviation /02z Wednesday through Sunday/...
VFR conditions are expected through Thursday night.
West to northwest winds are expected behind a cold front tonight
through Thursday night. Gusts up to 20 knots are possible
Wednesday afternoon and again Thursday afternoon.
VFR conditions for the weekend.
a pressure surge will produce 20-25 knots gusts over the waters in
the next few hours. Winds then should diminish late tonight and then
pickup again as mixing ensues.
A Small Craft Advisory may be also be needed for Wednesday night
Small Craft Advisory gusts likely Friday with incrsg southerly flow ahead of the cold
front. A brief lull is expected as the front passes Friday evening.
Strong cold air advection will keep gusty northwest winds over the water...with Small Craft Advisory
conditions lasting through the weekend for portions of the waters.
District of Columbia...none.
Marine...Small Craft Advisory until 6 am EDT Wednesday for anz531>534-
Small Craft Advisory from noon to 6 PM EDT Wednesday for
Small Craft Advisory until 10 PM EDT this evening for anz530-