Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260800 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 400 AM EDT Mon Jun 26 2017 .SYNOPSIS... High pressure will build west of the area through Tuesday. A cold front will cross the region Tuesday. High pressure will move over the region Wednesday and settle offshore late in the week. && .NEAR TERM /TODAY/... As of 3am, an upper trough stretches from the Canadian prairies to the Midwest then up over New England per water vapor imagery. A 1024mb surface high is centered over Kansas City. This surface high will drift east to the central Mid-Atlantic through Tuesday night before the center moves off the mouth of the Chesapeake Bay Wednesday. West flow and cold air advection under the upper trough will keep temperatures below normal through Wednesday night. A weak shortwave trough rounds the upper trough and crosses the Mid- Atlantic tonight. The airmass should be too dry for any shower development. However, the low 80s surface water temps of the Chesapeake will continue to be a notable moisture source. A shower cannot be ruled out near the Bay this afternoon. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... The upper trough axis crosses the area Tuesday night. This should provide enough forcing for widely scattered showers with isolated afternoon thunderstorms. Otherwise, expect the coolest day in three weeks with max temps in the upper 70s. Return southerly flow that begins late Wednesday behind the surface high. && .LONG TERM /THURSDAY THROUGH SUNDAY/... After a cool (for late June) period high pressure moves offshore Thursday and the heat and humidity return through the weekend. Still, not extreme heat: upper 80s/around 90. It is hard to pin down the exact timing/chance of precipitation several days in advance, but for now it looks like Saturday night/Sunday would have the best chances as a shortwave tracks north of the forecast area. 4th of July is still beyond the scope of this forecast, but for now neither the GFS or Euro shows anything too dangerous - Euro`s upper pattern is high zonal while GFS has a weak upper trough running down the eastern seaboard. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... VFR prevails through the week as high pressure slowly builds from the west. Passing shower/isolated thunderstorm Tuesday ahead of a cold front. VFR conditions expected Thursday and Friday. && .MARINE... NWly flow may gust to around 20 knots this morning, but confidence is low, so winds were capped at 15 knots. High pressure slowly builds through Wednesday. Return southerly flow begins Wednesday night as the high shifts to Bermuda. Winds expected to remain below SCA values Thursday/Friday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ PRODUCTS...BAJ/WOODY!

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