Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260753 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 353 AM EDT Tue Jul 26 2016 .SYNOPSIS...A front will become stationary across the area today, then drift southward on Wednesday. Another cold front is expected early next week. && .NEAR TERM /THROUGH TONIGHT/...A cold front has stalled across the Mid-Atlantic region this morning. Winds have become variable in most places and dewpts are in the 70s. Patchy fog is possible this morning mainly in areas that received rainfall Monday and Monday night. Little change in the surface pattern across the eastern CONUS today. The frontal boundary will stay stalled across the region and warm and humid conditions are expected again. There will be some relief across the nrn Mid-Atlantic as light northerly winds should bring dewpts down into the 60s. Further south...dewpts will likely stay in the low to mid 70s. Due to the heat and moisture heat indices will climb into the low 100s east of the Blue Ridge and south of Interstate 66 and around 105 across the Central Foothills, Tidewater region and Southern Maryland. A heat advisory is in effect for these areas this afternoon. Showers and thunderstorms are expected to develop this afternoon. Coverage will range from isolated near the MD/PA border to scattered across Central VA. A few storms may become strong to severe across the central Shenandoah Valley, Central Foothills and southern Maryland where instability is higher. Weak shear profiles will keep strong storms isolated. Coverage will diminish into the evening however any ongoing thunderstorms will likely continue as little change is airmass is expected. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...Zonal flow continues across the region Wednesday. The cold front is expected to move south Wednesday and into central and southern VA. There is some guidance that keeps the front northward along the east coast and therefore dewpts may not drop as much across central VA and southern Maryland. Thunderstorm coverage is expected to be less on Wednesday with a few forming across the higher terrain. If dewpts do not drop across the east coast a few thunderstorms will be possible in the afternoon. Activity will diminish into Thursday. The front lingers near the region Thursday and isolated showers and thunderstorms are possible in the afternoon and evening. A shortwave trough will approach the area Thursday night and coverage will likely become more widespread and heavy rain is possible. && .LONG TERM /FRIDAY THROUGH MONDAY/...Guidance shows heights falling across the region through the end of the week especially in the Thu-Fri evening time frame as a shortwave-trough digs across the ern Great Lks. Both the ECMWF and GFS show a low pres center tracking from the Carolinas newd to south of Long Island during the weekend with periods of rain affecting the area Fri into Mon. Widespread total rainfall amounts of an inch or more are likely during this period. Ignoring the GFS precip output which appear spurious generating a large area of 1-3 inches in a 6-hr period over northern VA and MD. Based on ensembles, the period of best rainfall potential appears to be in the Fri-Sat time frame. By Mon night, most guidance show a front clearing the area with enough dry air to suppress precip chances and enough cooler air to keep temps below 90F at least in northern areas. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... VFR conditions expected this morning. SHRA/VCTS expected this afternoon and evening with higher chance at CHO. Coverage will be isolated further north and confidence is low to put in TAFs at this time. Activity will likely diminish tonight and vfr conditions are expected. Isolated SHRA/VCTS expected Wednesday and Thursday afternoon. Sub-vfr conditions possible in activity. Risk of showers and t-storms will likely continue into the weekend as area remains under a very warm and moist air mass. Drier air not likely to make into the area until early next week. && .MARINE...A cold front has stalled across the waters this morning. Winds will likely become southerly today and remain below 15kts. Showers and thunderstorms possible today mainly across the southern half of the waters. Gusty winds are possible and SMW may be issued. Winds become nrly tonight and Wednesday. Isolated showers and thunderstorms possible Wednesday and Thursday afternoons. Sub-SCA conditions expected Fri through Mon, but higher winds and waves can be expected near thunderstorms. && .CLIMATE...Records were either broken or tied at all three main airports yesterday. A record high temperature of 100F degs was set yesterday at Dulles breaking the old record of 98F set in 2010. A record high temperature of 100F degs was set yesterday at BWI airport tying the old record of 100 set in 2010. A record high and a record high minimum were set at DCA yesterday. A record high of 100F was set tying the old record of 100F degs set in 1930. A record high minimum of 81F degs was set breaking the old record of 79F set in 1965. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Heat Advisory from noon today to 8 PM EDT this evening for MDZ016>018. VA...Heat Advisory from noon today to 8 PM EDT this evening for VAZ036-037-050-055>057. 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.