Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 221950 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 350 PM EDT Sat Apr 22 2017 .SYNOPSIS... A frontal boundary becomes nearly stationary across the Carolinas tonight and Sunday. Low pressure will slowly track along the southeast coast Sunday and Monday, then linger off the Mid Atlantic coast through mid week. This system will bring periods of moderate to heavy rainfall to the region. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... FYI...Results from the storm survey in the Colonial Beach area shows mainly straight line wind damage. Official statement to be issued later today. Latest MSAS has cold front draped across southern most Va zones and is progged to slowly sag south into NC this evening before stalling there overnight. Threat for strong to severe storms will be along and south of this boundary into the evening mainly west of I95. SVR WW Box 157 through 01Z. Fairly stable north of it as high pressure to the NW prodives an in-situ wedge scenario as rain continues to move in from the west. A decent feed of moisture results in likely to cat pops this evening (locally heavy downpours) then trailing off after midnight as the the wave moves east. Overcast with areas of rain, drizzle and fog overnight. Much cooler as the high to the NW provides the CAA. Lows 45-50 NW, 50-55 SE. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... A cloudy and wet period ahead with periods of mdt to hvy rainfall. QPF btwn 1.5 to 3.5 inches (highest across the Piedmont). Models in general agreement that a cut-off upr level low tracks SE across the lwr Mid Atlantic region tonight and Sunday. System then takes on a neg tilt that spawns a coastal low off the se coast Monday. This system get cut off from the main upr lvl flow which allows it to spin over the warm Gulf Stream waters Monday and Tuesday before slowly lifting NE Wednesday. Upshot will be for mainly cloudy skies with periods of mdt to lclly hvy rainfall through the period as copious amounts of deep Atlantic moisture gets entrained and rotates around the system. Thus, confidence high enough to go with likely to categorical pops each period. First shot of mdt to hvy rainfall will be Sunday, second one Sunday night and Monday and possible a third one Monday night. NAM more agressive than GFS with thunder chcs as the NAM actually brings the system inland thus allowing a warm sector to develop along the sern coastal areas. GFS keeps the system offshore. Thus, kept high pops but low chc thunder given the model differences. Highs Sun in the mid 50s to lwr 60s. Lows Sun nite in the upr 40s- mid 50s. Highs Mon in the mid 50s-mid 60s except 65-70 sern coastal areas. Lows Mon nite in the upr 40s-lwr 60s. Highs Tue in the lwr 60s-lwr 70s. Hydro wise, no flood headlines anticipated attm with numerous breaks in between bouts of rain expected. Do expect some healthy rises in local river by early next week, especially if the heavy rainfall falls over the headwaters. Given the forecasted QPF and after coord with the RFC, expect minor flooding at Lawrenceville on the Meherrin River by Tue. Again, this based on QPF so plenty of time to adjust if needed. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Long term period will feature a trend towards drier and warmer conditions. For Mon night/Tue, mid-level cutoff low and associated sfc low continue to spin south of the area, allowing for moisture to stream in off the Atlantic. Bumped up PoPs to likely for most of the area Mon night and chance far NW, with models tending to push cutoffs lows offshore too quickly. Slightly lwr PoPs for Tue, with the best chance near the cst. Temps Tue slightly below normal...highs in the upr 60s most spots. Warming trend then commences for Wed as deep SWly flow develops across the eastern seaboard, lasting through the end of the week with temps reaching the 80s most areas Thu and Fri. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... As of 18Z...A nearly stationary front is draped across southern portions of the forecast area. This front should continue to slowly drift south through the afternoon and evening hours. IFR ceilings, currently impacting SBY/RIC/PHF, will continue to expand to the south behind the boundary. Widespread IFR ceilings are expected tonight and into tomorrow morning as the front moves south of the region. Rain shower coverage is also expected to increase through the afternoon and evening hours for much of the area with MVFR visbilities possible in the heaviest showers. Winds turn to the NE and will be gusty at times behind the front, occasionally gusting in excess of 20 knots near coastal sites. Outlook: Lower pressure will linger off the Carolina coast through early next week. Unsettled conditions, widespread moderate to heavy precipitation, and degraded aviation conditions are expected Sunday through Tuesday. Drier conditions are expected on Wednesday and Thursday. && .MARINE... Latest surface analysis depicts a cold front over the waters with a weak area of low pressure over central Virginia. High pressure resides off the Southeast coast. The wind north of the boundary has become north to northeast, with a uptick in west to southwest winds south of the boundary thanks to showers. Waves generally 1-2 feet and seas 2-3 feet. Low pressure slides offshore mid morning as the front pushes south of the waters early afternoon. A lack of good cold air advection and gradient winds expected to keep north to northeast winds at or below 15 knots, but a few gusts to around 20 knots are possible early afternoon in the lower Bay. Seas build to 3- 4 feet this afternoon as flow becomes northeast over the coastal waters. High pressure builds in from the northwest tonight as low pressure lifts along the Northeast coast. Winds increase to 10-20 knots tonight, with gusts of 20-25 knots expected in the bay, sound, and coastal waters. Increasing northeast flow kicks seas up to 4-5 feet in the southern coastal waters tonight. Have raised SCA headlines for the aforementioned waters. Seas build to 4-5 feet in the northern waters Sunday morning. Gradient indicates SCA conditions may subside Sunday afternoon in the upper Bay, but speeds in the lower bay and lower James river increase to 15-25 knots. Gusts in the southern coastal waters increase to 25 knots. Seas build to 4-6 feet Sunday afternoon. Onshore flow prevails thru Tuesday as low pressure develops over the Southeast states then slowly slides offshore. As a result, an extended period of SCA conditions is anticipated with speeds of 15- 25 knots and seas building upwards of 5-8 feet (or higher). Current headlines run thru Sunday night (4th period). Improving marine conditions thereafter as the surface low weakens and pushes off to the northeast. && .TIDES/COASTAL FLOODING... An extended period of onshore flow will result in increasing tidal departures thru mid week. Tidal departures will reach +1 to 1.5 feet through Sunday night along the Atlantic coast and in the lower Chesapeake Bay and James River. Northeast flow increases Monday, with tidal departures of 1.5 to 2 feet. Minor flooding is expected Monday night thru Tuesday during high tide. Flow becomes offshore Wednesday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ632-634-654- 656-658. Small Craft Advisory until 10 PM EDT Sunday for ANZ633. Small Craft Advisory until 10 AM EDT Sunday for ANZ630-631. Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for ANZ638-650-652. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...MPR LONG TERM...MAS AVIATION...AJB MARINE...MAS TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.