Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 141620 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1120 AM EST Sun Jan 14 2018 .SYNOPSIS... Arctic high pressure builds in from the northwest today, then tracks east to a position over eastern Canada Monday. A cold front crosses the area Wednesday morning with low pressure staying offshore through the mid week period. && .NEAR TERM /THROUGH TONIGHT/... No major changes, with forecast mainly on track. Arctic high tracks north of the area today. Despite full sun, highs only reach upr 20s to around 30 north...low to mid 30s S/SE. Gusty NNE winds 15-25 mph gradually diminish by late aftn. Cold tonight as ridge axis extends down the spine of the mts. Tsctns show mid/high level moisture along the coast. Winds stay up along the coast but should decouple across the Piedmont. Lows 10-15 except upr teens to lwr 20s SE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Sfc high builds across New England/Ern QC, ridging down into the Mid-Atlantic. Quasi-downslope flow aloft will start an abbreviated moderating trend for Mon/Tue. After a cold start to the day, afternoon temperatures climb into the lower to middle 30s for most...some upper 30s to around 40 SE zones. Sfc high retreats farther NE Mon Night ahead of an approaching nrn stream clipper system and associated surface feature Mon night and Tues. Lows in the upper teens to mid 20s. Models remain in decent agreement that wx remains dry Tues. Developing pre-frontal S-SW flow allows for highs rebounding back into the 40s. Models a bit slower with the cold frontal passage Tues night with any pcpn holding off until after midnight. Data shows some upr level energy accompanying the boundary as it crosses the mts btwn 06Z-12Z Wed. Thermal profiles indicate snow with a progged QPF of less than one tenth inch. Will carry chc pops after midnight with accumulations of ~1" thru 12Z Wed across the Piedmont. Dry east. Lows in the 20s to near 30 SE. As of now, this looks like an advisory level event given timing/impact for the Wed morning commute. Added mention in the HWO. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... 14/00Z runs of the GFS/ECMWF/Canadian cont to offer up different solutions wrt how much moisture will be rung out Wed as the front meets up with energy off the coast (or not). ECMWF more robust and suggests a mdt snowfall across the local area (2-5 inches), GFS has less QPF thus a lighter snowfall (1-2 inches) mainly west of the Ches Bay while the Canadian indicates an inch or less. Given the different scenarios, did not make any changes to Wed forecast attm given snowfall amounts only need to go out 72 hrs. Kept chc pops (snow) with highs 30-35. Clr/cold Wed nite. Lows 10-20. On the good side, models in good agreement that flow flips flatter into the late week period, with temperatures strongly moderating to and above normal values once again into next weekend. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... VFR conditions through the 18z TAF forecast period as arctic high pressure results in mainly clear sky. SCT-BKN SC re-develop arnd 4K ft along the sern coastal sites late tonight. Gusty N winds 15-20 kts diminish after 18Z. Outlook: Unsettled into midweek, as potent upper trough brings thickening/lowering clouds by later Tue, with some flight restrictions possible into Wed morning. Some light wintry pcpn likely Tue night and Wed as clipper and associated cold front cross the region...with clearing late Wed. Predominate VFR then likely Thu/Fri as the trough ejects NE offshore. && .MARINE... Strong CAA continues early this morning driving a N wind of 20-25kt with gusts to around 30kt (~15kt for the Rappahannock/York/Upper James). Seas range from 5-7ft N to 7-9ft off the Currituck Outer Banks, and 3-4ft waves in the Bay (locally up to 5 ft at the mouth of the Bay). This will continue through the morning, before high pressure nudges in from the NW this aftn, allowing the wind to diminish to 15-20kt, but remaining 20-25kt off the nrn Outer Banks. Surface high pressure locates over QB tonight and builds to 1048mb. Meanwhile, low pressure will be situated well off the Southeast coast. This combination should result in a N wind of 15-20kt continuing tonight for the Bay/ocean/Sound and perhaps into midday Monday. This will help maintain seas of 4-5ft, and 5-7ft off the nrn Outer Banks. Current SCAs have been extended for 12 hours with the exception of the lower James. Freezing spray will be maintained for today into tonight due to the combination of the wind and an arctic airmass. The wind should diminish by Monday night and Tuesday as a weak surface ridge settles near the coast. A surface cold front crosses the coast Tuesday night, with strong CAA lagging behind until the upper trough arrives Wednesday night into early Thursday with SCA conditions likely for wind and seas. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 AM EST Monday for ANZ630>634. Small Craft Advisory until 4 PM EST this afternoon for ANZ638. Small Craft Advisory until 7 PM EST Monday for ANZ650-652-654- 656-658. && $$ SYNOPSIS...MPR NEAR TERM...MPR/MAM SHORT TERM...MPR LONG TERM...MPR/MAM AVIATION...MAM MARINE...AJZ

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