Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 201822 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 222 PM EDT Thu Oct 20 2016 .SYNOPSIS... High pressure will remain centered over the coastal Carolinas today...resulting in another unseasonably warm day. A cold front crosses the region on Friday...followed by breezy and much cooler, more seasonal conditions Friday night through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update...Special Weather Statement issued for fog across the Eastern Piedmont, South Central VA, MD/VA Eastern Shore, and inland Northeast NC through 930 AM this morning. Visibilities generally range from 1-2 miles with locally patchy dense fog of 1/2 mile or less. Previous discussion... Sfc high pressure remains centered over the coastal Carolinas with a developing warm front straddling the Mason-Dixon Line early this morning. Fog has developed late in the evening and overnight under mostly clear skies with calm winds. Overall coverage of fog will continue to be patchy (3-5SM), however typical fog-prone and rural areas will experience more areal coverage of fog with visibilities around 1SM (locally 1/2SM). Lowest visibilities will likely occur within a few hours either side of sunrise and then dissipate/lift by 900-1000 AM. Otherwise, the Mid Atlantic Region resides within the warm sector ahead of an approaching cold front, which will move across the lower Ohio Valley today. Although SCT-BKN mid level clouds will traverse far nrn counties this morning invof the warm front, this front will lift northward and skies will be mostly sunny for all areas by this aftn with light south winds. Another warm day ahead with high temperatures in the low-mid 80s (upper 70s beaches). && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... A strong upper trough and associated sfc cold front approaches the region from the west tonight and is expected to push through the area on Friday (penetrating the Ern Piedmont Fri morning and reaching the coast by Fri aftn). Expect increasing rainfall from west to east during the day, however qpf totals will be rather light (0.10-0.30 inches) due to pwats around 1.00-1.50 inches in this airmass. There isn`t much lift/omega aloft to support thunder Friday aftn and the strong 100kt jet streak nosing into the region is located well behind the sfc front. Have therefore kept thunder out of the forecast entirely. Rain comes to an end late Friday night as a cold Canadian high builds into the region behind the front. Meanwhile, a coastal low northeast of the Bahamas (possibly becoming a tropical cyclone) slowly tracks northward...staying well offshore. The interaction of the passing cold front with the coastal low (they are expected to merge Fri night) and the incoming cold Canadian high pressure will significantly tighten the sfc pressure gradient beginning Fri aftn. Strong W-NW winds will develop quickly Friday evening and persist through the rest of the short term forecast period...mainly due to a strong upper trough swinging through the area (accompanied by a 100kt jet streak) and strong cold air advection occurring as well. Winds will be highest along the coast where sustained winds will average 20-25 mph with gusts of 30-35 mph. Farther inland, gusts will average 20-25 mph. Temps will run a good 10-15 degrees above normal tonight ahead of the cold front. Expect lows in the lower 60s. For Friday, temps will be at to about 5 degrees above seasonal normals with highs in the upper 60s to lower 70s NW to around 75 degrees SE. Once cold air advection processes commence Friday night, temperatures will plummet to more seasonal values with lows in the mid-upper 40s (around 50 degrees far sern coastal areas). Cool and breezy Saturday with highs in the lower 60s and lows Saturday night in the lower 40s (mid 40s beaches). && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... High pressure builds into the area from the NW beginning Sun. This high is progged to settle across the Southeast States Sat night through Mon. The next cold front crosses the area late Mon and appears to do so dry. High pressure builds in from the north Tue and Wed. Highs Sat in the upr 50s to lwr 60s. Lows 40-45 except 45-50 Southeast coastal areas. Highs Sun in the low to mid 60s. Lows in the mid 40s to lwr 50s. Warmer Mon with highs upr 60s to lwr 70s. Lows in the lwr 40s to lwr 50s se. Highs Wed in the mid to upr 60s. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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High pressure is centered over Atlantic Canada as of 18z, with weak low pressure in vicinity of the Cumberland plateau. Sct cu has developed this aftn with bases of 4-5kft along with a 5-10kt southerly wind. Low pressure gradually lifts to the ne tonight as a strong upper trough digs across the Midwest. Meanwhile, low pressure lifts to the north over the subtropical wrn Atlantic. Some semblance of high pressure will linger in vicinity of the Mid-Atlantic coast late tonight into early Friday morning. This combined with modest low-level moisture will result in the potential for a period of ifr fog/stratus. All sites have the potential for ifr, with perhaps the exception of RIC, which will be on the cusp of the better potential to the east. Conditions improve after 14-15z, before the trough and associated cold front approach during the afternoon. This will bring a period of -shra from w-e during the aftn/early evening hours. The wind will increase behind the cold front with a w-nw wind averaging 15-20kt with gusts of 25-30kt along the coast and 10-15kt with gusts of 20-25kt farther inland later Friday night into Saturday. High pressure builds in from the west Saturday night into Sunday. Another cold front (dry frontal passage) sweeps across the area Monday with high pressure returning Tuesday.
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&& .MARINE... Relatively quiet conditions through midday Friday as S to SE winds today will avg around 10 KT, with a brief increase to 10-15 Kt late aftn and this evening. Waves to avg 1-2 ft, 2-3 ft seas. Winds shift to the SW Fri morning and then the WNW Fri aftn. Models continue to depict a cold front crossing the waters late Fri aftn into Fri evening. Expect a brief surge of higher winds with the frontal passage, but the main timeframe for a more extended period of higher winds will be Friday night through Sat morning. The forecast is still somewhat uncertain as to how quickly the pressure gradient tightens between the deepening low along the New England coast and the high pressure system to the west. Looking at GFS/NAM/ECWMF, all models show a period Fri night where the 925 to 950 mb winds avg 35-40 KT as corresponding temperatures from 850-950 mb plummet. Given the water temperatures hovering near 70 F, the mixing should be to at least 950 mb and thus gusts to 35 KT appear likely for the northern coastal waters and possible for the Bay and the remainder of the VA coastal waters. Have decided to issue a Gale watch for these areas due to the uncertainty with the next shift able to either go to Gale warning or Small craft advisory. Elsewhere, for the rivers and all NC waters, think Gales are unlikely and have raised Small craft advisory headlines. The offshore NW flow will keep seas from building to anything higher than 5-7 ft most areas (highest out 20 NM offshore). Bay waves build to 4-5 ft. Winds remain elevated Sat aftn through Sunday but should diminish to some extent. Another cold front crosses the area Late Monday. Possible minimal SCA behind this boundary as well. && .CLIMATE... A few high temperatures either tied or broke the previous records for Wed, Oct 19th. Record event reports have been sent, however this information will be updated below shortly. Please see RER products from the Core TEXT Products menu link (located at the bottom of our home page under "Climate & Air Quality". Meanwhile, very warm conditions will continue through today. Clouds across the far northern counties of the forecast area should be enough to squash the potential for tying a record at Salisbury. Record high temperatures for Oct 20th are listed below: * Record Highs for Oct 20th: RIC 89 (1984) ORF 87 (1984) SBY 84 (1984) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 4 PM Friday to 6 AM EDT Saturday for ANZ633-635>638. Gale Watch from Friday evening through Saturday morning for ANZ630>632-634-650-652-654-656. Small Craft Advisory from 8 PM Friday to 6 AM EDT Saturday for ANZ658. && $$ SYNOPSIS...BMD NEAR TERM...BMD SHORT TERM...BMD LONG TERM...MPR AVIATION...AJZ MARINE...LKB CLIMATE...AKQ is the U.S. government's official web portal to all federal, state and local government web resources and services.