Area Forecast Discussion
Issued by NWS Wakefield, VA

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136 FXUS61 KAKQ 200605 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 205 AM EDT Thu Oct 20 2016 .SYNOPSIS... High pressure will remain just offshore through Thursday, bringing warm and dry conditions to the local area. A cold front crosses the region on Friday bringing showers to the area. Cooler, more seasonable temperatures return to the region for the upcoming weekend into early next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Update...Adjusted fog coverage for the rest of tonight. Most of the region will remain patchy around 5 miles. However, typical fog-prone and rural locations should drop to roughly 1 mile in the next hour or so and remain low until an hour or two after sunrise. Passing mid to high level clouds across far nwrn counties and the MD Lower Eastern Shore may prevent visibilities from dropping to 1 mile until closer to daybreak. Will need to monitor ongoing trends to determine if a special weather statement is needed and also if patchy dense fog wording will be necessary. Previous discussion... Late this evening, weak high pressure was offshore and a frontal boundary was laying near the Mason-Dixon line. Dry wx expected overnight under a clear to partly cloudy sky...mainly as the Mid Atlc region is under the influence of an upper level ridge and the front stays off to the north. Lows in the 60s. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... A cold front and associated mid-level trough traverse the OH Valley Thu. Will maintain a dry forecast attm with moisture associated with an offshore passing tropical low expected to not impact the fa. Warm conditions continue Thu with highs in the low-mid 80s. Temps should stay a few degrees below records (see Climate section below for details). For late Thu night/Fri...aforementioned front and trough approach and eventually cross the Mid Atlc. Shras will move across the region from Fri morning through the aftn. The best chance of rain will be during the aftn hours, with likely pops areawide except se portions of the fa (50% pops). Thunder is psbl as well but kept out of the forecast for now with confidence not high enough to include yet. Temps Fri lwr than previous days...highs mainly 70-75. Chances of rain decrease fm west to east Fri evening/night as the frnt pushes offshore and drier air moves in from the west. Low temps Fri night mainly 45-50. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Last spoke of energy around the potent low over northern New England crosses the area Sat morning. This will usher in a cool/dry airmass on gusty WNW winds. The gusty winds diminish Sat night as high pressure builds into the area from the NW. This high 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 Tues 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 /06Z THURSDAY THROUGH MONDAY/... Sfc high pressure remains centered over the coastal Carolinas and fog has developed under mostly clear skies with calm winds. Overall coverage of fog will be patchy (3-5SM), however typical fog-prone and rural areas will experience more widespread areal coverage of fog with visibilities around 1SM (locally 1/2SM to 1/4SM...especially at KPHF). Lowest visibilities will likely occur within a few hours either side of sunrise, and then dissipate/lift by 20/1300-1400Z. 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. VFR conditions will prevail under mostly sunny skies with south winds aob 10kt. 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 on Friday with conditions generally ranging from MVFR to VFR and brief periods of IFR possible under heaviest rainfall. Meanwhile, a coastal low northeast of the Bahamas (possibly becoming a tropical cyclone) slowly tracks northward...staying well offshore. However, the interaction of the passing cold front with the coastal low (they are expected to merge Fri night), and a cold Canadian high pressure building in behind the front will significantly tighten the sfc pressure gradient beginning Fri aftn. Strong W-NW winds will develop quickly Friday evening and persist through at least Sunday before wind speeds gradually diminish. Winds will be highest along the coast where speeds will average 15-20kt with gusts of 25-30kt. VFR conditions prevail Sunday through Friday. High pressure over the SE states tries to build into the Mid Atlantic Region on Sunday, but will stay suppressed just to the south as another sfc low (similar to an Alberta Clipper) dives across the Great Lakes Sunday night and passes through srn New England on Monday. Cooler Canadian air building in behind the clipper will allow another round of gusty W-NW winds to develop Mon aftn through Mon night. Gusts could average 20kt near the coast. High pressure dominates the weather pattern Tuesday through the rest of the work week. && .MARINE... No headlines through Thursday night as the return flow around high pressure keeps S-SW winds below 15 kts. Waves 1-2 ft, 2-3 ft seas. Cold front progged to cross the waters Friday shifting the winds to the NW in the afternoon. Models continue to show a surge into SCA range behind the fropa starting late Fri afternoon. Will hold off on and SCA headlines with this package given a late 4th period starting time. Where the forecast becomes problematic is Friday night when an even stronger surge is noted due to a tightening pressure gradient between the deepening low over New England and the high pressure to the west. In addition, not exactly sure how the developing system out in the Atlantic will affect the forecast as it lifts north well east of the Eastern Seaboard. For now, will keep gusty winds in the forecast Sat and Sat night. However, latest data does suggest that gusts to gale force are possible late Fri night and early Sat across the northern coastal waters where the pressure gradient will be the tightest. Thus, bumped up gusts to 35 KTS across those areas Fri nite for now. Plenty of time to adjust if needed as later data comes in. Waves build 3-4 FT, seas 4-6 ft. 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. 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...None. && $$ SYNOPSIS...MAS NEAR TERM...BMD/MAS/TMG SHORT TERM...MAS LONG TERM...MPR AVIATION...BMD MARINE...MPR CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.