Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 270755 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 355 AM EDT Wed Jul 27 2016 .SYNOPSIS...A front will remain stationary across the area through Thursday then lift north Thursday night. Low pressure will track across the area Friday. High pressure builds for early next week && .NEAR TERM /THROUGH TONIGHT/...A frontal boundary is near the MD/PA border this morning and warm and humid conditions will continue across the Mid-Atlantic region. A weak shortwave trough will move to the north this morning and a few showers are possible. Winds are expected to be light and northerly and dewpts will drop into the upper 60s across the nrn outlook area today. The frontal boundary will move south of most of the region today and likely stall near central VA again. Scattered showers and thunderstorms are expected again today with the highest chance across central VA. Higher instability due to higher dewpts will also lead to a few strong to severe storms from the central Shenandoah Valley to southern MD. A few showers and thunderstorms can not be ruled out further north as instability will still be present. Higher dewpts will likely be further north along the Chesapeake Bay due to a onshore component to the wind. Temps will be cooler today with more cloud cover and heat indices should stay below 100 with the exception of the central Foothills where the dewpts are higher. Thunderstorms will be diurnally driven and should diminish this evening. Dewpts will rise back into the 70s resulting in another mild evening. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...500mb flow becomes W-SW Thursday in response of an approaching shortwave trough across the TN Valley. The frontal boundary will lift northward Thursday and Thursday night and the Mid-Atlantic will be in the warm sector. Scattered showers and thunderstorms are expected across the region Thursday afternoon as energy ahead of the shortwave trough moves into the region. Convection will likely persist into the evening hours and a few strong to severe storms are expected. Guidance has been depicting a sfc low moving near or across the region Thursday night into Friday. Uncertainty is low on timing and location but heavy rainfall is possible in an unstable moist airmass. The trough will pass overhead Friday and showers and thunderstorms will be possible. Subsidence behind the trough will likely lead to dry conditions Friday night. && .LONG TERM /SATURDAY THROUGH TUESDAY/...Multiple sfc waves and impulses aloft are fcst to move through the area during the weekend with the most significant of these Fri afternoon. Showers and t-storms will remain in the fcst through Mon as front remains nearly stationary across the area. By Mon night, most guidance show front pushing far enough south with sufficient dry air as weak high pressure builds in to suppress shower development everywhere with temperatures returning to more seasonable values in the mid to upper 80s. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... Prevailing VFR conditions expected today and tonight. SHRA/VCTS expected at CHO this afternoon. SHRA/VCTS possible at MRB/IAD/DCA however confidence is low. Coverage will increase Thursday afternoon with SHRA/VCTS expected across the region. Convection will continue Thursday night into Friday and some SHRA/TSRA may produce heavy rainfall resulting in longer sub-vfr conditions overnight Thursday into Friday. Periods of rain during the weekend especially on Sun which may cause some restrictions. Improving weather Mon night on as weak high pressure builds in. && .MARINE... Winds less than 15kts will continue on the waters. Showers and thunderstorms are possible on the waters today and gusty winds are expected in activity. Scattered showers and thunderstorms expected Thursday afternoon through Friday resulting in the potential for gusty winds through the period. SMW may be required in showers and thunderstorms. Winds generally 10 kt or less outside of thunderstorms, but winds and waves higher near thunderstorms. && .CLIMATE...Record high minumums were either tied or broken at DCA and IAD airports. New record high minimum of 80F degs set at DCA yesterday breaking the old record of 79F set in 1987. Record high minimum of 76F degs set at IAD yesterday tying the previous record of set in 2005. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...LFR NEAR TERM...HAS SHORT TERM...HAS LONG TERM...LFR AVIATION...HAS/LFR MARINE...HAS/LFR CLIMATE...LFR is the U.S. government's official web portal to all federal, state and local government web resources and services.