Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 171734 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1234 PM EST Fri Feb 17 2017 .SYNOPSIS... High pressure builds along the Gulf coast this morning, as low pressure departs to the northeast over the Canadian Maritimes. This area of high pressure slides offshore of the Southeast coast this afternoon into Saturday. A weak area of low pressure moves through the Carolinas Saturday night with high pressure returning by Sunday afternoon. && .NEAR TERM /THROUGH TONIGHT/... Latest analysis indicates sfc high pressure centered over FL, and ridging NNE into the Carolina/VA coastal Plain. A weak shortwave passing through the NW flow aloft in addition to mid level warm advection is resulting in a band of BKN-OVC clouds around 8-12kft are passing over Ern VA/ NE NC. Temperatures are rising through the 30s into the low 40s under cloud cover, and into the upper 40s/around 50 over the piedmont where clouds have cleared. For today, expect mostly cloudy skies through late morning over much of VA/northeast NC, but with fairly rapid clearing by midday with skies to become mostly sunny. After a cold start, the SW low level flow will allow for moderating temperatures with highs to reach around 60 F over south central VA, to the mid/upper 50s most other areas west of the Bay, and the upper 40s over the ern shore. Mid-upper level ridge axis slides E into the region tonight with mainly clear skies (some clouds over the NE). Lows mainly in the 30s. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... Mid-upper level ridging continues to build into the Mid- Atlantic on Saturday. Temperatures will continue to moderate Saturday with highs rising into the upper 60s to low 70s (upper 50s/low 60s at the immediate Atlantic coast of the Ern Shore). Have added a climate section for reference but due to fairly shallow mixing on Sat, think we will fall a little shy of reaching the records. Mid/high clouds increase Saturday aftn as a srn stream system pushes into the Tennessee Valley. This system is weak, but sky cover should become mostly cloudy by Saturday night. 17/00z models continue to show a split in the pcpn pattern with some light rain moving into central VA in closer proximity to the upper system, with another area generally staying S/SE of the local area in vicinity of a coastal boundary. Continuity has been maintained for PoP with mainly a 20-30% chc for Saturday night, with QPF less than 0.10". This system weakens offshore Sunday as weak high pressure builds in from the west. Above normal temperatures continue with decreasing clouds. Morning lows range from the mid 40s to around 50, followed by highs in the mid 60s to around 70 F (locally cooler at the coast). && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A weak coastal low/trough off the Southeast Coast will continue to track ESE Sun night. Meanwhile, sfc high pressure and high amplitude ridging build into the Mid Atlantic Region from the west and will reside over the area through Wed. A clipper system passing north of the Great Lakes late Mon night into Tue night will cause the sfc high to positively tilt (or lay down) and slide ewd/offshore on Tue; upper ridging also follows this pattern change. The sfc high slowly weakens going into Wed as it slides farther SSE and located well off the Southeast Coast. Still some uncertainty going into Wed night as another clipper system passes across the Great Lakes and along the St Lawrence River Valley while low pressure deepens in the Gulf. Overall, the Mid Atlantic Region sits within a region of split flow and will remain dry for the entire long range forecast period. Temperatures will also run about 10-15 degrees above normal. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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High pressure is sliding off the Southeast coast this afternoon, with the wind becoming light SW and averaging 5-8kt. The wind is still W at SBY at 8-12kt, but that will diminish through the aftn. A deck of 8-12kft clouds is steadily eroding early this aftn. Mainly clear tonight into early Saturday morning with some sct high clouds at SBY, and a light SSE then SW wind. Mid/high clouds increase Saturday aftn as an upper trough lifts into the Tennessee Valley. This system will push into the central Appalachians Saturday night, with weak low pressure reorganizing off the Southeast coast. The primary forcing will split the area with only a 20% chc of spotty light rain. High pressure returns later Sunday which will allow for dry and VFR conditions to continue into early next week. A weak cold front will cross the region Wednesday with only a minimal chc of light rain.
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&& .MARINE... Sub-SCA conditions have returned to the waters early this morning as high pressure builds into the region. Northwest winds have diminished at or below 15 knots. Few gusts to around 20 knots expected north of Parramore Island through day break. Seas 2-4 feet and waves 1-2 feet. For today...the ridge axis slides offshore early afternoon with flow becoming southwest at or below 10 knots. Waves subside to 1 foot and seas 1-2 feet. A warm front lifts over the waters late today into this evening. An extended period of sub-SCA conditions is expected through at least the middle of next week as models indicate warm and stable conditions. A cold front pushes across the waters Saturday night, but a lack of cold air advection and gradient winds will result in a northwest wind of 5-10 knots Saturday night through Sunday. High pressure builds across southeast Canada Sunday night and Monday, with flow becoming northerly. Speeds at or below 15 knots. Flow becomes northeast Tuesday as high pressure slides offshore, but remains at or below 15 knots. Seas 2-3 feet. Flow becomes southwest Wednesday ahead of the next weakening cold front. && .CLIMATE... Very warm once again for the weekend, currently not expecting to set record highs but it may be close so for reference the record highs are listed below: * Site Sat 2/18 Sun 2/19 * RIC: 77 (2011) 78 (1961) * ORF: 77 (1937) 73 (1907) * SBY: 75 (1976) 72 (1961) * ECG: 80 (1976) 77 (1939) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...BMD AVIATION...AJZ/LKB MARINE...SAM CLIMATE...AKQ

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