Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 252005 AFDAKQ Area Forecast Discussion National Weather Service WAKEFIELD VA 405 PM EDT Sat Mar 25 2017 .SYNOPSIS... High pressure remains offshore the southeast coast through Monday. A weak frontal boundary drops south to the Delmarva Sunday morning before lifting back to the north Sunday night and Monday. A cold front crosses the region late Tuesday through Tuesday night. && .NEAR TERM /THROUGH SUNDAY/... Latest analysis indicates surface high pressure centered well off the SE CONUS coast, with WSW flow aloft and S to SW at the sfc. A warm day with temperatures mainly ranging from the mid 70s to around 80 F. Skies are mainly free of low- mid clouds but a fair amount of high clouds are streaming across the area so will keep sky cover in grids of 30-50% into this evening leading to partly cloudy wording for most areas. Remaining dry/mild overnight ahead of low pres lifting ENE from the mid MS Valley into the OH Valley. A weak sfc boundary currently over NJ will drift south and settle over the ern shore by late tonight resulting in light onshore winds and increasing low clouds. Otherwise...S winds will prevail under mainly BKN-OVC cirrus farther S. Lows m-u40s on the ern shore to the l-m50s elsewhere. Will have mention of patchy fog late (after 5 am) though not anticipating dense fog. Weakening low pres (sfc-aloft) will continue to track NE the Great Lakes Sun-Sun night...pushing a weak low level boundary into/across the FA. Only SLGT forcing aloft w/ this system...which will likely limit pcpn coverage. Did raise sky cover to mostly cloudy/cloudy ern shore and partly-mostly cloudy elsewhere. Upper level shortwave brushes NW zones late and will have a 20-30% PoPs mainly confined to the NW after 21Z. Highs Sun to show a strong gradient with temperatures likely stuck in the 50s in low clouds over the MD eastern shore, with l-m70s inland (in VA/NE NC). && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Lows Sun night in the u40s- around 50F on the ern shore to the l-m50s elsewhere, with mainly dry conds and partly cloudy skies. Initial system lifts into/through New England Mon...leaving FA w/ continued mild/warm conditions as hi pres (sfc-aloft) remains invof SE CONUS coast. VRB clouds Mon w/ PoPs mainly aob 20%, though will have a small area of 30% PoPs across the far N through midday. Highs should warm a few degrees compared to Sunday, into the mid-upper 70s over much of VA and interior northeast NC to the upper 60s to lower 70s near the coast and over the eastern shore. Upper level ridging to keep it mainly dry and continued warm Mon night with lows in the 50s. Upper level trough pushes into the area on tue as a sfc cold front passes by late. continued warm with highs well into the 70s to near 80 F if rain holds off. There will be a higher chance for showers and aftn tstms. Will continue with 40-50% PoPs for now given some continued timing differences between the GFS/GEFS and slightly slower ECMWF. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Medium range period will remain mild, courtesy of warm southerly flow from lingering high pressure just offshore of the mid-atlantic coast. Other main weather feature of note will be a rather progressive mid-level shortwave traversing the western/central CONUS late Sat-Monday, before lifting E-NE across the mid-South toward the local area on Tuesday. High end chance POP remains in place for showers and sct T-Storms. While the system will be weakening, given decent instability and favorable diurnal timing, will continue thunder wording for all but far NE zones (later timing). Shortwave ridging behind the wave will bring slightly cooler, albeit still mild, and drying wx Wed and Thu. Forecast highs mainly in the 60s to near 70 far north and along the immediate coast...70s to near 80 west of the Bay on Tuesday, 60s to mid 70s on Wednesday...with temps trending back to around climo normal for the latter half of next week. Next chance of rain comes by the end of the period late next week in association with another weakening southern stream upper low traversing the southern tier of the country. For now, rain chances are re-introduced by late on Thu/Fri. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... High pressure centered offshore will allow for VFR conditions to continue through this afternoon and the first half of the night. Sub-VFR conditions will be possible late Saturday night and into Sunday as a boundary pushes south into northern portions of the area. Southwest winds, 10-15 knots with gusts of 20-25 knots, will persist through the afternoon and early evening hours before diminishing around sunset. MVFR and potentially IFR conditions will be possible early Sunday morning, mainly after 10Z, at RIC/SBY due to patchy fog/low ceilings. Conditions should improve by late Sunday morning besides SBY where low ceilings may linger into Sunday afternoon. A few showers will be possible by the end of the forecast period with only brief periods of reduced aviation conditions possible during times of precipitation. Outlook: Unsettled weather conditions will persist across the region through mid-week. Sub-VFR conditions will be possible late overnight and into the early morning hours primarily due to low ceilings. Scattered showers and thunderstorms will also be possible late Sunday night into Monday and once again late Tuesday into Wednesday. Periods of reduced aviation conditions will be possible during times of precipitation. && .MARINE... High pressure is well offshore with a weak wedge left in the lee of the Appalachians. This feature should delay the onset of rain until mid to late morning as a cold front continues to advance on the area...effectively outrunning (or getting ahead of) the precipitation by late morning/early aftn. Weak troughing along the coast will cause the pressure gradient to tighten invof the cold front. Meanwhile, weak warm air advection will act to hamper the development of stronger winds. Overall, winds become s-sw 10-15kt (up to 20kt nrn coastal waters) by early aftn; peaking during the cold frontal passage. Seas build to 2-4ft; waves to 2ft. Little change to the airmass tonight behind the front as warmer air stays in place with strengthening high pressure building well north of the waters through Sun night. N winds tonight through Sun aob 15kt...becoming ne-e and diminishing to aob 10kt Sun night. Seas average 2-3ft; waves average 1-2ft. Main high pressure slides over Nrn New England/Canadian Maritimes on Mon. E-se aob 10kt. Weak wedging remains in place in the lee of the mts as a very strong low pressure system tracks into the Upper Great Lakes Mon and across Ontario/Quebec Mon night. The pressure gradient tightens up late Mon night into Tue aftn ahead of the front and s winds will increase to 15kt Bay and 15-20kt all coastal waters. Seas generally build to 3-4ft in this timeframe (up to 5ft possible coastal waters north of Parramore Island). Waves generally 2ft; occasionally up to 3ft. SCA flags are not anticipated. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...ALB/LKB LONG TERM...TMG AVIATION...AJB MARINE...BMD/TMG is the U.S. government's official web portal to all federal, state and local government web resources and services.