Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 260009 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 809 PM EDT THU AUG 25 2016 .SYNOPSIS... A weak cold front passes through the Mid Atlantic Region Friday afternoon and evening. High pressure then returns to the area Saturday into most of next week. Warmer and more humid conditions will prevail. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Weak leeside troughing this aftn has resulted in sct-bkn cirrus across the nwrn half of the CWA and sct-bkn cumulus across far SE VA and NE NC. All clouds are expected to clear by midnight tonight. Shallow ground fog potential is diminishing but is still possible around sunrise Fri morning. Meanwhile, a weak cold front crosses the Ohio Valley tonight. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... The approaching weak cold front is expected to push through the area Fri aftn/evening. Despite anticipated sct aftn cumulus development and slowly increasing dewpoints ahead of the front, deep moisture/lift is shallow and very limited by stable conditions above 850mb. Therefore, confidence for isolated showers/storms is low. As per the past several days, clouds will dissipate and clear around sunset. Temps warm to 90-95F with dewpoints in the low 70s. As a result, heat index values will creep into the low 100s but heat advisory criteria (104-109F) is not anticipated at this time. The front moves well offshore of the Mid Atlantic coast by Sat morning and extends down to the Southeast coast. Any potential shower activity will likely stay shunted south of the area due to high pressure returning to the region. Little airmass change anticipated in the post-frontal environment. Therefore, dewpoints in the low 70s (upper 60s possible far nw counties) and slightly cooler temps in the low 90s will be commonplace. Heat index values may touch 100 degrees for an hour or two in far SE VA and inland NE NC east of the Chowan River but will be patchy at best. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Medium range forecast period characterized by continued dry/warm conditions for much of the period, courtesy of persistent mid/upper level (Subtropical) ridge that becomes anchored over the Southeast and Mid-Atlantic. (Low) Rain chances slowly creep back into the forecast by the middle of next week. There remains good support amongst the deterministic models, and many of their respective member ensemble means, that the upper level ridge will remain in place through midweek, even as it dampens overhead Tue/Wed. Resultant low-level flow over the local area veers from E-NE Sunday and Monday, to the W-NW Tue-Wed. Model differences ramp up significantly for the latter half of next week, and center mainly around the fate of tropical disturbance Invest 99L in the Northern/Central Caribbean. There remains support for tropical energy to push across the Bahamas and eventually the Florida Straits over the weekend, potentially reaching toward the ne Gulf coast and parts of the Deep South early next week. The operational 12z/25 GFS now is a bit closer to the latest 12z/ECMWF solution, albeit still weaker. Either way, there remains no strong support for widespread pcpn over the local area thru Wed. However, given the trends of continued breakdown of the upper ridge overhead and gradually increasing PW values, continued inclusion of a slight chc to low end chc (20-30%) for iso to sct showers/tstms is reasonable and has been maintained in the forecast for Wednesday and Thursday. Rain chances will remain highest over the southern third of the area. Temperatures should average at or above normal through the period. Forecast highs Monday through Wednesday range from the mid 80s at the coast to the upper 80s/low 90s inland. Early morning lows through the period average in the upper 60s to mid 70s. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... A ridge of high pressure over North Carolina will yield to a cold front dropping southeast from the Great Lakes will move through to Virginia Friday night. This front will dissipate during the weekend. High pressure builds back into the area Sunday through Tuesday. South to southwest winds are expected overnight due to pressure gradient between high pressure to the south and seasonably strong low pressure across southeast Canada. Left fog out of the forecast as winds are not expected to go calm but will still need to monitor for patchy ground fog. Despite the cold front moving into the area late Friday...the atmosphere appears too dry for thunderstorms. A dry forecast is in place through Tuesday. && .MARINE... Latest obs reflect Southerly winds ~10-15 kt this afternoon. High pressure will slide farther offshore through tonight. Expect a modest surge with winds tonight, as pressure gradient briefly tightens ahead of a very weak cold front, which approaches from the nw late tonight and Friday. A brief period of near-SCA winds are possible in the Bay tonight through about midnight. Will hold off with SCA flags given very short duration of surge, and can handle with Marine Statements as needed. Winds remain southerly ahead of the front Friday, but diminish to 5-10kt, with pressure gradient quickly slackening as the front drops across the area and washes out overhead early Saturday. High pressure then settles off the New England coast and ridges south across the region Sunday into early next week. This will translate to a period of prolonged, albeit predominately sub-sca onshore flow averaging 10-15kt early next week. Seas average 2-3ft Fri/Sat with 1-2ft waves in the Bay, with seas increasing to 3-4 ft Mon/Tue, with wavewatch favoring seas 4-5ft out well offshore. Tropical cyclone Gaston is expected to track to a position east of Bermuda by early next week. This should result in long period swell propagating toward the coastal waters, with seas remaining 3-5ft, again highest out near 20nm. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...BMD NEAR TERM...BMD SHORT TERM...BMD LONG TERM...MAM AVIATION...LSA MARINE...MAM is the U.S. government's official web portal to all federal, state and local government web resources and services.