Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 161654 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1154 AM EST Tue Jan 16 2018 .SYNOPSIS... High pressure will slide offshore today into tonight. A cold front crosses the area Wednesday morning with low pressure moving northeast along the coast Wednesday afternoon and night. A second surge of arctic air pushes across the area Wednesday night into Thursday before temperatures moderate into next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Relatively rare microphysics event unfolded across RIC metro area this morning. Have had a few reports of some light snow/flurries from southside RIC proper into Prince George county. With <-5 C layer still quite dry per morning soundings and forecast cross- sections, GOES-16 nighttime microphysics imagery showing a narrow boundary of subtle llvl convergence in the FZFG which is creating some light snow below the radar beam (KAKQ and surrounding radars have been quiet throughout aside from some clutter). We`ve posted a story on our social media channels (Facebook/Twitter) with more information. Freezing fog issues have largely abated inland, with fog scouring out nicely...finally allowing temperatures to climb into the 30s to near 40. Along the SE coast, fog likely hanging on into early afternoon, and have cut highs back accordingly into Hampton Roads/Tidewater. Next round of business will be re-accessing Winter WX headlines into tomorrow. Preliminary look at 12z data indicates an eastward expansion of advisory into Hampton Roads/Tidewater/NE NC is likely. Will attempt to have updated headlines by 19-20z. Previous discussion... Current wv imagery and model analysis depicts a potent upper trough digging across the Midwest, with broad SW flow aloft from the Gulf coast across the Mid-Atlantic and into coastal New England. At the surface, 1040+ mb high pressure is retreating to the NE over ern Canada, but the surface ridge axis still extends well to the SW into the Mid- Atlantic. Meanwhile, an inverted trough is located off the coast, and light NE flow associated with this feature has pushed a marine layer inland with fog and stratus covering much of the area with the exception of the far wrn Piedmont. Temperatures early this morning range from the upper teens over the Piedmont to the low 30s along the coast. High pressure will gradually erode today with the inverted trough still lingering off the coast. Therefore, fog and stratus will be slow to erode this morning, and mixing will be limited today. This will offset modest mid-level WAA and high temperatures today will only rebound to the low/mid 40s, which are near seasonal averages.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... The potent upper trough will pivot sewd tonight across the Ohio Valley and into the Cumberland plateau, with the cold front pushing across the mountains and into the Piedmont by 06-12z Wednesday. The vigorous upper level feature will continue to trundle ewd across the region Wednesday as the cold front gradually pushes through the region with snow overspreading the region and affecting the commute Wednesday morning across wrn and central portions. Pcpn could briefly begin as rain, especially toward the coast. 16/00z GFS/ECMWF/NAM/CMC demonstrate decent agreement with this feature, with some slight timing differences in the latter stages, mainly 18-00z Wednesday with the ECMWF/CMC slightly slower. Given this, PoPs have been increased to categorical across the Piedmont after 06z tonight into midday Wednesday, and for central and s- central VA Wednesday morning. Likely PoPs have been maintained for SE VA/NE NC, with likely PoPs for the Middle Peninsula/Northern Neck/Lower Ern Shore tapering to chc for the Lower MD Ern Shore. Model consensus supports QPF of 0.2-0.3" across the Piedmont and s-central VA and Northampton NC, bordered by 0.1-0.2" from central VA to SE VA and NE NC, with 0.1" or less farther NE. Expect some variability in SLRs, but generally ratios of 12-15:1 are expected during the highest PoPs, which supports 2-4" of snow across the Piedmont, with 1-3" for the I-95 corridor of central and s-central VA into Northampton NC. Given this, a winter weather advisory has been issued for these locations generally beginning late tonight and extending into Wednesday aftn. There is the potential for a narrow band of negative EPV over the SW Piedmont and there could be a very narrow corridor of 4-6" of snow. This would be very localized and hard to pin- down, so there is no need for a watch or warning at this time. We will need to watch for sharpening axis of f-gen/OPRH depicted by the high-res NAM as it may portend to a period of moderate snow even into Hampton Roads Wednesday aftn. No advisories have been issued yet for Hampton Roads, but may eventually be necessary as it could affect the aftn commute. High temperatures will generally be 30-35F, but will likely fall into the mid/upper 20s across the NW half of the area during the aftn. The sky will clear quickly Wednesday night as a quick shot of arctic air surges into the region. Shallow mixing is expected to persist overnight, which should inhibit temperatures from plummeting too far. Still cold nonetheless with lows in the mid teens inland to the upper teens/low 20s for coastal SE VA/NE NC. Mid-level WAA resumes rather quickly Thursday with 850mb temperatures of -2 to -4C at 12z warming to +4-6C by 21z. A cold start to the day, limited mixing, and mid-level WAA should result in rather stable lapse rates and surface high temperatures should only reach the upper 30s to low 40s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Pattern change looks to occur during the medium range period with a significant warmup expected through the upcoming weekend/early next week. It will still be on the cold side Thu night with sfc high pressure centered across the deep south, and one last upper trough moving SE through the Great Lakes and off the New England coast Fri morning. Mostly clear skies will prevail over the local area with lows mainly in the 20s though depending on remaining snow cover, some upper teens will be possible across interior southern VA. Latest GFS/ECMWF/CMC depict the upper trough moving well off the New England coast Fri with a broad upper level ridge building over the eastern CONUS Fri aftn through the weekend. Expect continued dry conditions with warming temperatures, highs in the upper 40s/lower 50s Fri, rising well into the 50s (possibly near 60F) Sat, and into the 60s (except at the immediate coast/eastern shore) for Sun. Lows Fri night/Sat am in the mid 20s to mid 30s, and Sat night/Sun am in the 30s to around 40F. SOme timing differences arise by Sun night/Mon, but overall expect increasing clouds ahead of the next front Sun night and will carry a chc for showers Mon/Mon night. Mild with lows in the 40s and highs Mon mainly in the 60s. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Wide variety of conditions this with primarily IFR to LIFR ceilings for the eastern half of the CWA and mainly clear skies/VFR west of I- 95. Fog continues to linger mainly along and east of I-95 across the area of low ceilings, fog may be locally dense at times. Conditions slowly improve through day today with lower ceilings/visibilities expected to linger near the coast through the early afternoon. Conditions will deteriorate once again Tuesday night as a potent upper level trough brings thickening and lowering clouds. Light winds will average 5 knots or less for the most part which will tend to keep an onshore flow at the immediate coast, but shifting to the S well inland. Outlook: Expect flight restrictions on Wed with snow showers as clipper and associated cold front crosses the region. Clearing Wed night with breezy N winds near the coast. Predominate VFR then likely Thu/Fri as the trough ejects NE offshore. && .MARINE... Marine Dense Fog Advisory is in effect until 10 AM EST for all the waters minus the northern ocean zones. Cams/sfc obs continue to show visibilities under 1 nm. Fog will slowly dissipate through the morning. High pressure centered over eastern Canada and ridging to the SSW along the piedmont has resulted in NNE winds of 10 to 20 knots across the waters this morning. Seas range generally range from 4 to 7 feet and waves range from 1 to 2 feet (up to 3 feet at the mouth of the Bay). SCAs have been extended for the coastal waters as seas will remain at or above 5 feet, especially out 20 nm, today. Winds are expected to diminish this afternoon as a weak surface ridge settles near the coast. A surface cold front crosses the the coast Tuesday night with strong CAA lagging behind until the upper trough arrives Wednesday evening into Thursday. Winds become NW Wednesday and increase to 15 to 25 knots by Wednesday evening. SCAs were extended over the coastal waters through Thursday due to current seas and anticipated wind/seas with the next event. SCAs will likely be needed for the Bay as well Wednesday night into Thursday. High pressure settles over the area by Thursday afternoon and Thursday night, and then slides off the Southeast coast Friday. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...Winter Weather Advisory from 6 AM to 6 PM EST Wednesday for NCZ012. VA...Winter Weather Advisory from midnight tonight to 3 PM EST Wednesday for VAZ048-060>062-069-509-510. Winter Weather Advisory from 6 AM to 6 PM EST Wednesday for VAZ081-087>089-092. Winter Weather Advisory from 3 AM to 6 PM EST Wednesday for VAZ065>068-079-080-511>516. MARINE...Small Craft Advisory until 1 PM EST Thursday for ANZ650-652- 654-656-658.
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&& $$ SYNOPSIS...AJZ/MAM NEAR TERM...AJZ/MAM SHORT TERM...AJZ/MAM LONG TERM...LKB AVIATION...AJB MARINE...AJB

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