Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 150027 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 727 PM EST Tue Feb 14 2017 .SYNOPSIS... Low pressure moves across the southeastern states tonight, then moves offshore as a cold front crosses the area Wednesday. High pressure builds into the region Thursday through Saturday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Latest MSAS has sfc high moving off the coast with the mid level shortwave trof tracking south across the fa. Most if not all the echo coverage this afternoon has been aloft (virga) as low levels remain dry (dp temps in the 20s resulting in rh`s btwn 30-40%). This feature progged to drift south into the evening hours keeping skies cloudy across the south, mstly cloudy across the north. Kept the forecast dry through late evening given CIGS above 8K ft. Models deamplify the moist srn stream shortwave as it tracks ENE across the south tonight. Meanwhile, a potent/anomalous northern stream upper low digs over the Great Lakes region. Northern stream cold front reaches the WVA/VA border late tonight, while the srn stream low lifts into the southern Mid-Atlantic region. This will quickly spread moisture across the region as an elongated area of isentropic lift increases and height falls spread into the region after 06Z. Pops quickly ramp up (into likely category) mainly south of a SBY-OFP-FVX line with categorical pops across the swrn piedmont zones after 09Z. Tsctns show the potential for a sharp moisture gradient north of this line resulting in less QPF with only chc pops there. Lows in the upr 30s to lwr 40s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Upper level jet couplet over the region will also aid in favorable forcing for ascent Wed. With increasing pw`s, could see an few hour period of mdt rainfall across sern zones through 18Z or so ahead of the advancing cold front. Kept high end likely to categorical POPs across the southeast half of the forecast area through mid afternoon Wed. Sharp cut-off in pcpn expected across the northwest Piedmont as the northern stream cold front drops into the region and dry air surges in behind the front. The front pushes across the region late Wednesday afternoon, with precip pushing offshore by 00Z Thu. Appears enough dry air comes in for some partial sun across the Piedmont late. This makes for an unusual temp forecast where the coolest readings (upr 40s to near 50) will be across the south where the rain/clouds hang on the longest with the warmest readings (lwr 50s) across the piedmont given any sun. Total QPF ranges from just a few hundredths across northern most zones, up to a quarter inch close to a WAL-RIC- FVX line to around one third inch across the se. Trough axis pushes offshore Wed evening with sfc high pressure building south across the nations mid section. Drier air overspreads the region resulting in mostly clear to partly cloudy skies. CAA on NW winds allows temps to drop into the mid-upr 20`s, except lwr 30`s near the coast. Dry/cool Thurs as high pressure builds in from the west. Highs in the 40s. Lows Thurs night in the mid 20s to lwr 30s. Dry/warmer Fri as low level thicknesses rise. Highs 50-55 west of the Ches Bay, mid-upr 40s along the coast. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Long term period will feature mainly dry weather with slowly increasing temps through the period. For Fri night, an upr-level shortwave ridge builds into the area with sfc high pres remaining in the vicinity. Expect low temps in the 30s under a mostly clear sky with light southerly flow. Winds remain southerly into Sat as low- level thicknesses rise, allowing for well above normal temps...highs in the low/mid 60s most areas; upr 50s Lwr Ern Shore. Southern stream trough approaches the region Sat night, pushing across the region Sun. An associated weak area of low pres is progged to lift along the SE coast. Clouds increase Sat night along with a slight chance of rain over the srn half of the FA. The trough pushes offshore Sun night with dry and clearing conditions. High temps Sun and Mon in the mid 60s most areas; near 60 Lwr Ern Shore. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
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Mid and high level clouds will continue to increase tonight for all TAF sites as low pressure develops south of the region. Light rain is expected to develop after 06Z at RIC/PHF/ORF with heavier rain developing at all TAF sites after 12Z. Visbilities could be occasionally reduced to IFR in heavier bursts of rain Wednesday morning and into early afternoon. MVFR ceilings also develop at all TAF sites after 12Z with some potential for IFR ceilings, especially across southeastern portions of the area, into Wednesday afternoon. A cold front pushes through the region Wednesday afternoon bringing an end to the rain and a return to VFR conditions for the end of the forecast period. Outlook: VFR conditions are expected Wednesday night through Saturday. Winds will be gusty behind the front on Thursday, winds could occasionally gust in excess of 20 knots out of the NW. The next potential for sub-VFR conditions will be Saturday night and into Sunday as weak low pressure lifts along the southeast coast.
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&& .MARINE... Sub-sca conditions continue tonight as sfc high pres slides offshore. Expect southerly winds up to 10-15 kt over the wtrs with 1- 2 ft waves over the Bay and 2-4 ft seas over cstl wtrs. Winds/waves/seas then ramp up late in the day Wed as a cold front slowly crosses the wtrs. Expect sca conditions to commence over the Bay/Sound/cstl wtrs Wed eveng, but started headlines at 4pm as there may be some gusts near 20 kt over the Bay/Sound or 5 ft seas out 20 nm starting shortly after then. Continued these headlines through Thu aftn as CAA continues. May need to issue a SCA for the rivers as well at some point but held off for now with it being 4th period there and marginal. Marine conditions then slowly improve Thu night through Sat as weak high pres builds into the area. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 4 PM Wednesday to 7 PM EST Thursday for ANZ630>634-650-652-654-656-658. && $$ SYNOPSIS...MPR NEAR TERM...MPR/LSA SHORT TERM...MPR/SAM LONG TERM...MAS AVIATION...AJB MARINE...MAS is the U.S. government's official web portal to all federal, state and local government web resources and services.