Area Forecast Discussion
Issued by NWS Wakefield, VA

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773 FXUS61 KAKQ 080601 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 101 AM EST Thu Dec 8 2016 .SYNOPSIS... Weak trough moves over the local area overnight. Weak low pressure tracks along the Virginia North Carolina border Thursday morning through early afternoon...followed by a cold front later Thursday afternoon. Canadian high pressure builds into the area Friday through the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Weak trough sfc-aloft will be crossing the FA overnight w/ periods of cloudiness. Very low prob for any pcpn. There is currently patchy ground fog at a few locations now...will likely continue overnight. For now...leaving out fog mention. Lows ranging from the l-m30s N to the u30s-l40 S. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... The aforementioned srn stream system quickly tracks across the region in vicinity of the VA/NC border Thursday morning through early aftn. A shear axis and strong flow aloft will provide subtle forcing for ascent along with pw values of 0.5-0.9". Downslope flow and marginal moisture return will be limiting factors for pcpn. Forecast PoPs are 20-30% and highest over se VA/ne NC, with any QPF on the order of a few hundredths of an inch. A vigorous upper trough will dig over the Great Lakes Thursday and push the aforementioned cold front through the Ohio Valley and into the Mid-Atlantic region by late aftn. Mostly cloudy to overcast most of the day with clearing arriving in the Piedmont by mid-late aftn as the cold front pushes through. Cloud cover should hold highs in the upper 40s to low 50s. Much colder air surges into the region Thursday night as the large arctic high continues to build through the central Conus and nudges ewd into the Southeast. 850mb temperatures drop to -8 to -10C (-1 to -2 st dev) late Thursday night. Lows drop into the mid/upper 20s under a quickly clearing sky. A cold/brisk day is anticipated Friday as the Arctic high builds from the Central Plains toward the srn Appalachians. 850mb temps drop to around -10C (-2 st dev) Friday afternoon. Strong CAA will prevent temperatures from reaching their full potential Friday afternoon, even with a sunny sky. MOS guidance continues to show highs generally in the low/mid 40s, but these numbers seem on the high-side. Some Piedmont locales may struggle to get out of the 30s, with around 40/low 40s elsewhere. A brisk northwest wind of 10-15 mph inland and 15 to 20 mph near the coast is expected to keep wind chill values in the low to mid 30s. The high builds into the region Friday night into Saturday. By this point the airmass will have modified enough to lose its arctic characteristics. Still cold and well below normal nonetheless, with lows Friday night in the upper teens to low 20s inland, to the low/mid 20s for se coastal locations. Limited mixing Saturday will keep highs in the upper 30s to low 40s despite some warming at 850mb. Sunny with a light nw wind becoming sw. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Sfc high pressure slides overhead Sat night and offshore by Sun morning. Winds become more southerly and breezy...especially as a weak coastal trough begins to develop along the Carolina and Mid Atlantic coasts Sun night. Meanwhile, another upper level trough digs across the Midwest and Ohio Valley Sun/Sun night...followed by a strong cold front pushing through the area Mon and a more progressive, westerly flow pattern aloft for Tue/Wed. A brief warm-up should be anticipated with the coastal trough Sun night into early Mon...along with increasing chances of precipitation Sun evening through Mon evening with the passage of a cold front. The Piedmont may remain wedged and keep cooler air in place prior to the initial onset of precip. This could result in precip starting as light snow showers Sun evening before quickly transitioning to all rain overnight. Precip should remain as rain through Monday, however if any precipitation lingers into Mon night, it could easily transition back to light snow showers as another round of cooler, modified arctic air and sfc high pressure return to the region Mon night through mid week. Temperatures generally at to slightly below normal throughout the period. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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A weak area of high pressure remains over the region early this morning, resulting in VFR conditions and light winds. Expect some patchy fog over the Piedmont through daybreak, with patchy ground fog closer to the coast. Increasing mid level clouds over the southern forecast area will limit any further fog development, so have only tempoed a few hours of IFR ground fog at the usual culprits of KPHF and KECG. A cold front pushes across the region late morning into the afternoon, with increasing low to mid clouds along the boundary. Broken to overcast ceilings will lower to MVFR for a brief period along the front, with clearing skies post frontal. Isolated to widely scattered showers are possible, but rainfall amounts will be light. VFR conditions return all sites this afternoon as Canadian high pressure builds into the region. Surface winds become west to southwest around 10 knots this afternoon. High pressure builds into the area Thursday night through Saturday. High pressure slides offshore Sunday as another cold front approaches from the west. This cold front crosses the region Sunday night into Monday. with a chance for rain.
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&& .MARINE... A weak cold front crosses the waters late this aftn into this evening...with cooler air filtering down over the waters the rest of tonight into Thu. Winds generally nw-n aob 15kt during this timeframe. Seas have been slow to subside through today, and have therefore extended SCA flags for ocean through 500 AM Thu morning when seas finally drop below 5ft. Meanwhile, an upper level trough sits just north of the region on Thu...slowly sagging swd Thu night and then sliding across the area on Fri. Winds become more wnw as the day progresses with speeds remaining aob 15kt. Wind speeds increase to 15-20kt Thu evening for Bay/Ocean/Sound/Mouth of James River as a strong 125-150kt jet sags south over the waters in advance of the upper trough. A much colder arctic airmass arrives after midnight Thu night as the sfc pressure gradient tightens and speeds increase to 20-30kt (aforementioned areas) and 15-20kt (Rivers); still w-nw direction. SCA flags will likely be issued beginning with this initial surge in winds. Gale force gusts may still be possible (especially as skies clear with the strong jet streak overhead), however confidence is low at this time. The cold air begins to equalize and the sfc pressure gradient starts to relax late Fri night into early Sat as sfc high pressure axis shifts ewd and closer to the waters. Winds remain within solid SCA speeds through Sat morning before diminishing below 15kt all waters by Sat aftn. Seas build to 5-7ft north (possibly up to 8ft near 20nm Fri evening)/5-6ft south by Fri morning and are expected remain steadfast through early Sat morning before subsiding below 5ft by Sat aftn. The high slides overhead Sat night (light/variable winds) and offshore by Sun morning. Winds become more sly on Sun with a possible surge in speeds to 10-15kt into Sun night as a weak coastal trough starts to develop off the Carolina and Mid Atlantic coasts. The trough axis is expected to stall just offshore on Mon with winds becoming more sw-w aob 15kt. Seas average 2-3ft Sat night through Sun Night and may build to 4ft near 20nm on Mon. Waves 1-2ft. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 5 AM EST early this morning for ANZ650-652-654-656-658.
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&& $$ SYNOPSIS...AJZ/ALB/SAM NEAR TERM...ALB SHORT TERM...AJZ/SAM LONG TERM...BMD AVIATION...SAM/LSA MARINE...BMD

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