Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 222029 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 429 PM EDT THU SEP 22 2016 .SYNOPSIS...
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Low pressure along with a weak frontal boundary will remain stalled along or just off the Southeast and Mid Atlantic coast through Friday morning. High pressure builds over the local area later Friday into Saturday morning. A backdoor cold front drops across the region during Saturday. The center of high pressure slides into southeast Canada during Sunday.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Late this aftn, areas of showers continued to affect cntrl, SE, and Scntrl VA, and NE NC, with a few showers still producing heavy downpours. Otherwise, there was a little more brightening of the sky ovr the CWA, with even some sunshine ovr extrm Nrn/NW counties and ovr NE NC counties. As a result, temps climbed into the mid 70s to lower 80s most areas. Lingering low pressure and a frontal boundary along or just off the SE and Mid Atlc coast, will maintain the chc for at least sctd showers ovr the srn/se half of the region this evening into Fri morning. Heavier downpours will diminish during this evening. Lows will range fm the lower 60s to the lower 70s.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
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The combination of nrn stream energy and the coastal low/associated upr trough weakening, will finally result in decreasing pops and rain chcs ending ovr the sse Fri into Fri night. Will carry slight chc to low end chc pops (20-30%) acrs srn/se areas only during Fri. Surface high pressure will build over the region Fri night into Sat morning resulting in dry wx everywhere. Highs on Fri will range fm the upr 70s to mid 80s. Lows Fri night in the mid 60s to near 70. A backdoor cold front will drop acrs the region during Sat, and the cntr of sfc hi pressure will bld twd SE Canada by Sun morning. Will maintain dry wx during this period, with generally a partly sunny sky on Sat. Highs will range fm the upr 70s to lower 80s acrs most of the area. Expect more clouds ovr the Piedmont Sat night. Lows will range fm the mid 50s to the mid 60s.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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Medium range period begins Sunday with an amplified upper level ridge/trough pattern, the ridge axis being centered across the TN/OH Valley with a deep trough over Atlantic Canada. This much the GFS/ECMWf and ensembles are in good agreement with. By Monday, the models really begin to diverge however, the GFS and GEFS mean being much stronger than the ECMWF with an upstream trough over the upper midwest by Mon/Tue. this would lead to more of a strong blocking pattern that would keep the eastward progression of upper ridge axis much slower, becoming aligned along the east coast by late Tue/Wed. The CMC is even slower to push the upper ridge off to the east than the GFS/GEFS. Bottom line is a lot of model uncertainty beyond Monday. For Sunday/Mon, surface high pressure is progged to become centered over eastern Canada with a piece of the High ridging down into the northern mid-Atlantic states by Monday. Deep moisture will be pushed south of the local area, but expect more clouds than sunshine for Sunday (except over the eastern shore where more sunshine should prevail). Have also lingered 20% POPS for much of the area Sunday, shifting to the SW and far W zones Sun night/Mon. Highs will average in the low-mid 70s with lows in the upper 50s to mid 60s Sun/Mon. Did more a broad-brushed 20% POP by late Tue-Thu as high pressure becomes centered somewhere off the NE/northern mid-Atlantic coast and deeper moisture and a slow moving front gradually approach from the W. Highs will avg 75-80 F Tue-Thu with lows mainly in the 60-65 F range.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/... Low pressure continues to sit off of the South Carolina coast, bringing the region unsettled conditions. Showers have developed across portions of the area this afternoon in the moist air mass. Showers are most predominant in portions of south central Virginia. Radar trends show the shower activity continuing to move west across the area. Have left VCSH in the short term forecast for all TAF sites due to the moist air mass and relatively scattered development of these showers. Am expecting mainly MVFR/VFR cigs for the rest of the afternoon across the TAF sites. Once again, am expecting stratus to develop overnight, thus have introduced IFR cigs at all TAF sites after 06Z. Cigs will improve across the region after 13Z and we should generally see a return to MVFR conditions. Winds across the area are generally onshore around 10-15 knots with occasional higher gusts near the coast. Outlook: Conditions will continue to improve through Saturday with VFR conditions returning as high pressure builds over the region. Drier conditions look to continue into the first half of next week with the highest chances for rain mainly focused to the west of the area. && .MARINE... Latest obs reflect ENE flow across the waters as Pressure gradient remains compressed between high pressure well north into New England and weakening low pressure lingering along/just off the SE coast. Seas have dropped off to 4 ft or less for NC waters so have cancelled the SCA headline there (remaining in effect for the rest of the coastal waters and mouth of the Bay). Winds of 15kt gradually drop off from late this aftn through tonight as pressure gradient slackens a bit further. Winds turn more northerly and pick up a bit by Fri night as weak low finally nudges offshore. A weak Cold front drops across the waters late Friday Night into Saturday, stalling just south of the waters Sat night and Sunday before sliding south into the Carolinas on Monday. CAA surge behind the front appears minimal...but SCA for hazardous seas possible over the weekend as longer period swell begins to mix in Friday night through Sunday. && .HYDROLOGY... The Cashie River at Windsor will be cresting over 15 ft this aftn (major flooding begins at 13 ft), and will linger at this level into the evening before slowly subsiding. The Cashie River is not expected to fall below flood stage until early Friday afternoon. && .TIDES/COASTAL FLOODING... As of 17Z, tidal departures continue to avg +0.5 to 1.0 ft over the marine area, but no tidal flooding is occurring and no advisories are needed at this time. Will continue to monitor however, as tidal anomalies may build nwd through the Bay by later this aftn which could lead to some marginal tidal flooding by this evening farther up into the Bay. Moderate risk for Rips expected for Thu. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 AM EDT Friday for ANZ650-652-654. Small Craft Advisory until midnight EDT tonight for ANZ634-656. && $$ SYNOPSIS...TMG NEAR TERM...TMG SHORT TERM...JDM/TMG LONG TERM...LKB AVIATION...AJB/MPR MARINE...LKB HYDROLOGY...AKQ TIDES/COASTAL FLOODING...AKQ

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