Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 150533 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1233 AM EST Mon Jan 15 2018 .SYNOPSIS... Arctic high pressure will extend south into the region through Monday. A cold front crosses the area Wednesday morning with low pressure staying offshore through the mid week period. A second surge of Arctic air pushes across the area behind the system for midweek...before temperatures moderate into next weekend. && .NEAR TERM /THROUGH TODAY/... Latest wx analysis reveals ~1045mb sfc high pressure over the St. Lawrence Valley into northern New England, with a sfc ridge of high pressure extending down into the Carolinas this evening. To the west, low pressure continues to slide SE across the northern plains toward the upper midwest. Aloft, a strong upper ridge was building across AK into the PAC NW. This feature is shunting a strong shortwave trough SW across the Canadian Prairies toward the Dakotas. It is this feature that will eventually move downstream toward the OH valley through midweek and bring our next chance at some wintry weather. Mainly clear/cold this evening, though BKN/OVC stratocumulus over the ocean is beginning to push onshore along the NC coast already, and will gradually overspread much of SE VA/NE NC and the eastern shore after midnight. Winds stay up along the coast but should decouple across the Piedmont. Early morning lows will be coldest/ 10-15 F across the Piedmont and portions of central VA, while areas along the NE NC coast will have lows in the mid 20s with mixing and increasing low clouds. Sfc high will be in place over New England into Ern Quebec, ridging down into the Mid- Atlantic coast. Quasi-downslope flow aloft will start an abbreviated moderating trend in temperatures for Mon, with temperatures a few degrees milder than what occurred earlier today. However, have bumped up cloud cover a little more for areas near the coast and for all of the eastern shore as stratocumulus will be in place (skies avg out partly sunny farther inland). Maintaining the chance for flurries over the northern neck and MD eastern shore in association with the previously referenced weak disturbance lifting north along the coast into the northeast. GEFS probs and model cross sections continue to indicate we`re too dry in the sub-cloud layer and very dry aloft through the dendritic growth zone for accumulating precip...but we could see a few flurries/sprinkles Mon, before the dampening shortwave lifts north into New England. After a cold start to the day, look for afternoon temperatures to climb into the lower to middle 30s for most...some upper 30s to around 40 possible interior NE NC and south central VA. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... 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 agreement that wx remains dry Tues. Developing pre- frontal S-SW flow allows for highs rebounding back into the 40s. Upper trough will pinwheel SE down across the upper midwest into the Ohio Valley Tuesday and Tuesday night. The previously referenced sfc low will weaken across the Ohio Valley, with the sfc front lingering along the mtns Tuesday, before getting shunted east late Tue night and Wed. Of the 12z/14 suite, the latest GFS is quickest/most aggressive with shunting the upper wave...and the front through the local area. The NAM/ECMWF are slower/more bullish with digging the shortwave down in the mid- south, closing the upper low off for a time. The Canadian CMC is a decent middle ground solution that is not quite as fast as the GFS but is a good middle ground solution, especially given forecast preference toward more progressive system given expected upper flow . Have therefore trended toward a CMC weighted Canadian/GFS blend with POP/sky timing...which results in light snow/snow showers across the piedmont after midnight Tuesday night, to metro RIC by Wed morning. The F-Gen band slides east to the coast into late Wed aftn, spreading snow east to the rest of the area before pushing offshore by Wed evening (perhaps some brief mixing with -ra along the Albemarle). Still on track for an advisory level event for at least the western half of the area. For now, have aligned snow totals generally 1-2", T-1" east...though expect QPF/Snow totals will jostle around some more as models come more into range. Will retain mention in the HWO for now. Departing upper trough will usher in another quick burst of arctic air for Wed night into Thursday. Lows Wednesday night back down into the teens to around 20. Could see some high single digits possible inland Wed night. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Lingering chc of snow or snow showers early Wed night, then high pressure will build into and over the region for late Wed night into Fri. The cntr of the high will set up south of the area or off the SE coast for late Thu night thru Sun. The high will provide dry wx for Thu thru Sun, with moderating temps thru the period. Highs will be in the mid to upper 30s Thu, in the 40s to near 50 Fri, in the upper 40s to mid 50s Sat, and in the mid 50s to lower 60s Sun. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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MVFR SC btwn 2-4K ft continue to spread onshore this morning and are forecasted to move as far west as the I95 corridor after sunrise. Thus, VFR conditions to start off the forecast period will quickly lower to MVFR along coastal sites thru the pre dawn hrs. Per Tsctns, went with a few hour tempo group erly for the transition then basically socked in all coastal TAF sites with OVC MVFR conditions (203K FT) through 00Z Tue. NAM/GFS hinting at some IFR CIGS by 00Z at ECG but held off on going that low for now. Also, a few flurries are psbl across the ern shore later today but these should not be an aviation hazard. RIC stays VFR although BKN SC arnd 5K FT will flurt with that area today. NNE wind remain gusty btwn 10-20 kt at ORF/ECG with winds generally aob 10 kts. Outlook: Unsettled into midweek, as potent upper trough brings thickening/lowering clouds by late Tue, with some flight restrictions possible into Wed. 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.
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&& .MARINE... SCA`s will remain in effect for the Ches Bay and Currituck Snd until 7 or 10 am Mon morning, and in effect for the Coastal Waters thru Mon night, due to continued N winds (CAA) 15-20 kt with gusts up to 25 kt. Seas will range fm 4-6 ft N to 5-8 ft off the Currituck Outer Banks. Waves 2-4 ft. Otherwise, sfc high pressure cntrd over extrm SE Canada late this aftn, will lift NNE thru Mon, while low pressure well off the SE coast lifts NNE off the Mid Atlc and New England coast. The wind should diminish by Mon night into Tue, as weak sfc high pressure settles near the coast. A surface cold front crosses the coast Tue night, with strong CAA lagging behind until the upper trough arrives Wed night into early Thu with SCA conditions likely for wind and seas. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 AM EST this morning for ANZ634. Small Craft Advisory until 7 AM EST this morning for ANZ630>633. Small Craft Advisory until 5 AM EST Tuesday for ANZ650-652-654- 656-658.
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&& $$ SYNOPSIS...MAM NEAR TERM...LKB/MAM SHORT TERM...MPR/MAM LONG TERM...TMG AVIATION...MPR MARINE...TMG

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