Area Forecast Discussion
Issued by NWS Wakefield, VA

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374 FXUS61 KAKQ 100306 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1006 PM EST Fri Dec 9 2016 .SYNOPSIS... Canadian high pressure settles over the Mid-Atlantic tonight into Saturday, before sliding offshore Sunday. A warm front will lift through the region Sunday night as low pressure moves into the Great Lakes. This area of low pressure will push north of the area Monday, with the associated cold front crossing the region late Monday. Another strong cold front impacts the region during the middle of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... The current surface analysis shows large, sprawling 1042+mb arctic high pressure centered across the Canadian Prairies of srn AB/SK, extending south through the Northern Plains. An extension of the high has broken off and pushed east into the Ohio/Tennessee River Valleys early this evening, with the associated airmass spilling over the mountains. Forecast in good shape this evening, with only minor changes to reflect latest obs. Sfc high pressure continues to build over the region overnight. By this point the airmass will have modified enough to lose its arctic characteristics, dewpoints in the teens locally. Still clear and cold, with early morning lows well below normal nonetheless. Look for minima to settle into the upper teens to low 20s inland, low/mid 20s over SE coastal locations. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Cold high pressure (~1032-1034mb) remains over the area Saturday through Saturday night. This will result in limited mixing during the daylight hours Saturday and will keep highs in the upper 30s to low 40s under a sunny sky. A nrn stream trough dives into the Great Lakes region, which could result in increasing high clouds late, especially across the north. There should still be several hours of rather ideal radiational cooling conditions and lows should once again drop at into the upper teens/low 20s, with 25-30F for coastal se VA/ne NC. This initial wave shears out and pushes north of the region Sunday with as a more potent wave dives into the upper Midwest. The surface high slides offshore, but warming will be tempered by limited mixing and increasing clouds. Forecast highs will still be below normal and moderate only into the mid 40s to around 50 se. The vigorous nrn stream wave dives through the Great Lakes Sunday night and a srn stream wave precede it and pushes through the Tennessee Valley. This will result in a warm front lifting through the Mid-Atlantic. Sunday night lows will likely occur during the evening hours, ranging from the mid 30s nw to the low/mid 40s se. Clouds thicken and lower, with PoPs actually increasing along the coast initially as some semblance of a coastal trough pushes newd ahead of the approaching system and interacts with the warm front. No frozen pcpn is expected at this time across the far nw Piedmont counties as temperatures are expected to remain above 32F and slowly rise once any pcpn arrives from the nw later Sunday night. The srn stream wave tracks across the region through midday Monday, with the nrn stream wave moving toward the Saint Lawrence Valley by aftn, which will push the associated cold front into the area. Forecast PoPs are highest from morning through mid-aftn. Deep- layered w-sw flow will limit QPF, which at this time is forecast to be aob 0.3". Milder with highs ranging from the mid 50s nw to the mid 60s se. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A cold front associated with low pressure tracking along the St Lawrence River Valley and srn Ontario is expected to cross the region Mon evening and exit the coast by Tue morning. Although sw winds should be breezy ahead of the approaching front, the cooler air behind it is much more modified and n winds are expected to diminish Mon night into Tue morning as weak sfc high pressure moves quickly into the region. Onshore/ne winds develop Tue aob 15kt under partly sunny skies. The high slides offshore by Tue evening as a low pressure system developing over the TN Valley advances newd twd the Carolinas and Mid Atlantic Region...impacting the entire forecast area on Wed. Another blast of colder arctic air is possible very late Wed night into Thu. Overall, temps will be at to slightly below normal Mon night through Wed night... becoming much colder Thu (-1 Std Dev) with highs in the upper 30s nw to lower 40s se. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A clear sky and northwest winds will prevail during the 00Z TAF period with high pressure in control. Gusty winds that were present during the afternoon have diminished to around 5 knots and are expected to average less than 10 knots on Saturday. A few gusts to around 12 to 15 knots could occur at SBY Saturday afternoon. Also at SBY...few to sct mid level clouds off the Great Lakes may show up from time to time. OUTLOOK...High pressure slides offshore on Sunday. There will be a chance for rain Monday as a cold front approaches from the west. Following the passage of the cold front Monday night, dry weather returns for Tuesday. A chance of rain returns to the forecast Wednesday as another cold front approaches. && .MARINE...
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10 PM update... Cancelled SCA in the rivers as winds have dropped below SCA criteria with slow downward trend expected to continue. Sfc high pressure continues to build into the area tonight through Sat night. Meanwhile, a secondary surge in wnw winds is occurring this aftn and is expected to persist into this evening before cold air advection processes subside and a strong jet streak exits the region along with the base of a 500mb trough. SCA flags in effect for all waters except Currituck Sound; end times range from midnight through early Sat morning (a few hours before sunrise). Waves 3-4ft... subsiding to 2-3ft late this evening. Seas 4-5ft...subsiding to 3-4ft early Sat morning. The building sfc high slides overhead Sat night into Sun morning with light and variable winds. The high then slides offshore by Sun aftn/early evening and winds become more s-se aob 15kt. The combination of a weak coastal trough developing along the Southeast Coast Sun night and a warm front lifting north through the area should bring rain up along the Mid Atlantic coast late Sun night into Mon morning with a period of dry conditions possible over the waters the rest of the day on Mon. Seas average 2-3ft/waves 1-2ft. A cold front associated with low pressure tracking along the St Lawrence River Valley and srn Ontario is then expected to cross the waters Mon evening and exit the coast by Tue morning. Sw winds now forecast to be a tad stronger ahead of the approaching front, and SCA conditions may be possible during the day Mon (15-20kt Ocean/Bay/Sound...10-15kt Ern VA Rivers...4-5ft seas nrn coastal waters). The cooler air behind the cold front is much more modified and n winds are expected to diminish Mon night into Tue morning as weak sfc high pressure moves quickly into the region. Onshore/ne winds develop Tue aob 15kt. The high slides offshore by Tue evening as a low pressure system developing over the TN Valley advances newd twd the Carolinas and Mid Atlantic Region...impacting the waters on Wed. Seas average 2-4ft Tue through Wed/waves 1-2ft.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 AM EST Saturday for ANZ630>632- 634-650-652-654-656-658.
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&& $$ SYNOPSIS...AJZ/SAM NEAR TERM...AJZ/MAM SHORT TERM...AJZ/SAM LONG TERM...BMD AVIATION...AJB/LSA MARINE...BMD/LSA

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