Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
251 FXUS61 KLWX 260730 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 330 AM EDT Sun Jun 26 2016 .SYNOPSIS... High pressure will build overhead through Sunday. High pressure will move off the coast Sunday night. A cold front will move through the region late Tuesday into Tuesday night. The boundary will remain nearby during the middle and latter portions of the week. && .NEAR TERM /THROUGH TONIGHT/... High pressure remains over the region early this morning...bringing mainly clear skies. Patchy fog has developed...especially across central Virginia into the valleys of the Potomac Highlands. Locally dense fog is possible...but widespread dense fog is not expected at this time due to dewpoints holding in the lower 60s for most locations. The high will remain over the region today...bringing plenty of sunshine along with seasonably warm conditions and low humidity. Dewpoints will mix down into the middle and upper 50s for most locations and max temps will be in the middle to upper 80s for most areas. The high will begin to build to the south and east tonight...but it will remain close enough for more dry and comfortable conditions. Min temps will be in the lower to middle 60s for most areas. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... High pressure will settle out over the Atlantic for Monday while a cold front approaches from the Great Lakes and Ohio Valley. A southerly flow will increase moisture across the area during this time. Seasonably warm conditions and noticeably more humid conditions are expected. Dewpoints will rise into the mid to upper 60s across most areas. A pressure trough ahead of the cold front will develop overhead while a weak upper-level disturbance will pass through the area. These two features will act as lifting mechanisms to combine with an unstable atmosphere...resulting in some showers and thunderstorms. Some thunderstorms may be capable of producing gusty winds and hail...especially near and west of the Blue Ridge Mountains into central Virginia where instability may be greater due to deeper moisture. The pressure trough will remain overhead Monday night...resulting in a few more showers and thunderstorms...especially near and east of the Blue Ridge Mountains. The best coverage may be in the evening and the threat for stronger thunderstorms should diminish overnight due to the loss of daytime heating. A cold front will pass through the region late Tuesday into Tuesday night. A few more showers and thunderstorms are possible...especially during the afternoon and evening hours. Coverage should remain isolated to scattered due to a dry slot working its way in around an upper-level disturbance to our north. However...shear profiles may be a bit stronger in response to the upper-level disturbance. This may cause a few storms to produce gusty winds or hail. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... General agreement amongst the 00Z model suite with cold front south of the CWA by 12Z Wed morning with surface high sprawled across the Great Lakes region and attempting to build east into the Mid- Atlantic. 24 hours ago models were showing an upper level pattern that would keep the cold front stalled near the vicinity of the forecast area, but the latest runs are showing the high may be enough to nudge it offshore, despite the persistent upper level trough for the second half of the week. While the forecast is trending towards a drier solution now for Thursday, will hold from completely pulling PoPs out until multiple runs showing consistent thinking with the placement of the front. Another cold front will swing through the region next weekend as its associated low tracks through southern Canada with increasing chances of showers and thunderstorms beginning Friday and lasting through the weekend. Temperatures generally around normal for the extended period. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... High pressure will remain over the terminals through tonight. Patchy fog is expected this morning...especially across KCHO. Otherwise...VFR conditions will prevail through this evening before patchy fog returns overnight. A few showers and thunderstorms are possible Monday and Tuesday...especially during the afternoon and evening hours each day. Thunderstorms may contain brief downpours that cause IFR conditions along with the potential for gusty winds. Generally VFR conditions Wed into the weekend with possible sub-VFR with any shower or thunderstorm. && .MARINE... High pressure will remain over the waters through tonight before settling over the Atlantic Ocean for Monday. A southeast flow is expected today...but winds will remain below SCA criteria. Winds will increase a bit on Monday due to a stronger gradient ahead of an approaching cold front. However...guidance diverges a bit on how much the winds will increase. A small craft advisory may be needed for portions of the waters Monday afternoon...but confidence is too low at this time to issue one due to the difference in guidance and the fact that the waters will be relatively cooler than the air around it...possibly decreasing the amount of mixing that occurs. A small craft advisory may be needed for portions of the Bay and lower Tidal Potomac River due to southerly channeling winds. A cold front will pass through the waters late Tuesday into Tuesday night and northerly winds behind the boundary may gust close to SCA criteria overnight Tuesday. A few showers and thunderstorms are possible Monday and Tuesday...mainly during the afternoon and evening hours. Some thunderstorms may contain gusty winds. Generally sub-SCA conditions on all waters behind the cold front Wed through the end of the week. && .TIDES/COASTAL FLOODING... Tidal anomalies are around one-half to three-quarters of a foot above normal early this morning. The onshore flow will continue today...but it will be light so the anomalies should not change too much from where they are now. This will cause water levels to be close to minor flooding thresholds for sensitive areas during the high tide cycle this morning...the higher of the two. However...latest trends for water levels to fall just short of these thresholds so and advisory has not been issued at this time. Anomalies will have to be watched throughout the rest of this morning. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...Sears AVIATION...BJL/Sears MARINE...BJL/Sears TIDES/COASTAL FLOODING...BJL is the U.S. government's official web portal to all federal, state and local government web resources and services.