Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 310825 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 425 AM EDT TUE MAY 31 2016 .SYNOPSIS... A frontal boundary will remain near the region through Thursday night. A cold front will pass through from the west later Friday into Friday night. High pressure may briefly build into the area Saturday before a stronger cold approaches Sunday before passing through Sunday night into Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Quick update to issue Dense Fog Advisory for areas of eastern West Virginia...central Virginia...and central Allegheny County in Maryland. Fog will create reductions in visibility to a quarter of a mile or less in the early morning hours. Previous Discussion... Weak boundary, barely noticeable except for weak wind shift and slight decrease in dew points, will continue sinking southward through the region this morning. Have seen areas of fog develop, and these will continue through the early morning hours until it lifts and dissipates after sunrise. Otherwise, looking at a mostly sunny day for most with light east/northeast flow behind boundary. Closer to the boundary across far southern Maryland and into central Virginia/West Virginia may see a few showers/thunderstorms develop today with 500-1000 J/KG MLCAPE and convergence along boundary, along with added lift from the higher terrain of the Blue Ridge and Allegheny Highlands. Severe storms not likely with very weak wind field. Highs generally 82-87F.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... Another weak boundary will approach the area this evening and tonight, but should largely stay north of the region and wash out as it propagates southward. May re-inforce light northeast flow as it does so. Some hi-res guidance does try to bring a few showers/storms towards western/northern Maryland along boundary, so have placed in some slight chance POPs there for a few hours this evening. Otherwise a generally quiet night with additional fog development likely. Lows upper 50s to mid 60s. Wednesday will continue to see light easterly flow with high pressure nosing into New England. Will see additional chances for a few showers/thunderstorms, especially areas along the Blue Ridge and west closer to remnant boundary and higher terrain. Again, severe storms not expected. Highs low 80s. High pressure builds further down the coastline Wednesday night into Thursday, keeping area in light easterly flow. This will be best chance for marine layer with potential for low clouds/fog Wednesday night into Thursday morning before breaking Thursday afternoon. Later on Thursday will also see gradual approach of cold front from the west. Shower/thunderstorm chances again highest west of the Blue Ridge and Allegheny Front with easterly flow, terrain enhancement, and approaching front. High temps Thursday will be dependent on cloud cover and extent of possible marine layer but will show upper 70s to low 80s for now. Cold front will be on the doorstep of the region by Friday morning. && .LONG TERM /FRIDAY THROUGH MONDAY/... A cold front will slowly pass through the area later Friday into Friday night...bringing the chance for some showers and thunderstorms. The best chance for convection will be during the afternoon and evening hours. Seasonably warm and humid conditions are expected ahead of the front with max temps in the 80s for most locations. Weak high pressure may briefly build into the area Saturday behind the front. A couple showers and thunderstorms cannot be completely ruled out...especially across central Virginia where there may be a little more moisture. However...coverage will be limited and most areas may end up dry and seasonably warm. A stronger cold front will approach from the west Sunday before passing through Sunday night into Monday. A southerly flow will allow for warm and humid conditions ahead of the boundary...and this will cause more instability. The instability will combine with forcing from the front to trigger some showers and thunderstorms. Some thunderstorms may contain gusty winds and hail along with locally heavy rainfall. Cooler and less humid conditions are expected behind the front early next week...but an upper-level trough will build overhead during this time. Most of the time should turn out dry due to the dry air advection...but a couple showers cannot be completely ruled out due to the upper-level trough overhead. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... A variety of flight categories early this morning with areas of IFR or lower conditions in low clouds and fog. Will see these conditions break after sunrise with VFR expected area-wide for the remainder of the day. Could be an isolated shower or thunderstorm near CHO but will leave out for now due to low confidence/coverage. Additional areas of fog possible again later tonight into Wednesday morning, along with some isolated/scattered showers/thunderstorms Wednesday afternoon, especially MRB/CHO. Sub- IFR conditions possible yet again Wednesday night into Thursday with marine layer. Winds generally less than 10 knots through Thursday, ranging from NE-SE. Low clouds and patchy fog are expected early Friday...but cigs should improve throughout the day. However...there will be a few showers and thunderstorms that develop during the afternoon and evening hours as a cold front moves through. Drier air should move in behind the cold front overnight Friday and Saturday...bringing vfr conditions to most of the terminals. There still may be enough moisture for a popup shower/thunderstorm Saturday afternoon in central Virginia near KCHO. Another cold front will approach the terminals Sunday into Sunday night. There is a better chance for thunderstorms ahead of this boundary. && .MARINE... Sub-SCA winds expected through at least Wednesday with surface flow generally northeast to southeast less than 15 knots. Near- SCA conditions possible Wednesday night into Thursday. A cold front will pass through the waters late Friday into Friday night. A few showers and thunderstorms are expected ahead of the boundary. Weak high pressure may build in behind the front for Saturday. The gradient should be weak enough for winds to remain below sca criteria during most of this period. There is a better chance for thunderstorms Sunday into Sunday night ahead of an approaching cold front. Gradient winds may gust close to sca criteria from the south during this time. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Dense Fog Advisory until 8 AM EDT this morning for MDZ502. VA...Dense Fog Advisory until 8 AM EDT this morning for VAZ026>031- 036>039-050. WV...Dense Fog Advisory until 8 AM EDT this morning for WVZ050>053- 055-502-504-506. MARINE...None.
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&& $$ SYNOPSIS...BJL NEAR TERM...MM SHORT TERM...MM LONG TERM...BJL AVIATION...BJL/MM MARINE...BJL/MM is the U.S. government's official web portal to all federal, state and local government web resources and services.