Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 181844 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 244 PM EDT Thu Aug 18 2016 .SYNOPSIS...
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High pressure builds in through Saturday with a cold front crossing the area Sunday. High pressure returns for the first half of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Latest obs this afternoon indicating weak boundary to the south of the CWA. Light northwest to west flow injecting in drier air, with dew points in the 60s to low 70s. Meso models still suggesting a stray shower or thunderstorm could pop up, mainly terrain driven, through the late afternoon/early evening with just enough instability still in place. Anything that does form will be brief and sub- severe. Precipitation will taper off by the end of the evening with loss of daytime heating. Dry weather through the night, with patchy fog possible in the valleys.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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High pressure centered to the southwest will nudge into the region on Friday. Initially dry conditions Friday morning. However, a passing upper level disturbance by the afternoon combined with marginal instability could provide enough forcing to trigger afternoon showers and thunderstorms. Not anticipating anything in the severe nature, but would be more scattered in nature compared to this afternoon. Loss of the diurnal heating will suppress any thunderstorms Fri night, but with the shortwave energy still in the region, isolated showers are possible overnight. Another shortwave on Saturday with a similar surface setup will provide yet another day of scattered showers and thunderstorms, still remaining sub-severe. Temps during this time period just slightly above normal.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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A moderate cold front is expected to move slowly eastward across the Great Lakes region Sunday. This front could spawn a few thunderstorms, mainly in the afternoon and along and west of the Blue Ridge Mountains. Showers and thunderstorms could linger Sunday night and Monday as the front moves toward the Chesapeake Bay and possible stalls just east of the bay. High pressure will build in behind the front Monday night and linger through Wednesday. Drier air and slightly cooler temperatures are expected. High pressure will weaken Wednesday night and Thursday and move east. A return flow will enable temperatures and humidity to increase slightly.
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&& .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Generally VFR conditions for the TAF period. Isolated showers/thunderstorms possible, mainly KCHO/KMRB/KIAD this afternoon and then again Friday afternoon. Scattered showers and thunderstorms possible all TAF sites Saturday. Winds through Saturday generally less than 10 knots from the W-NW. IFR conditions at MRB and CHO terminals Sunday morning; MVFR conditions at other terminals. IFR conditions at all terminals Sunday afternoon and night. Winds southeast Saturday night becoming south Sunday then southwest Sunday night.
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&& .MARINE...
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Sub-SCA conditions on all the waters through Saturday. An isolated shower or thunderstorm is possible each afternoon which could bring gustier winds. No marine hazards expected Sunday through Sunday night. Winds south becoming southwest around 10 knots.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...Sears NEAR TERM...Sears SHORT TERM...Sears LONG TERM...KLW AVIATION...Sears/KLW MARINE...Sears/KLW

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