Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 221814 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 214 PM EDT Sat Apr 22 2017 .SYNOPSIS... Several weak waves of low pressure will move across a nearly stationary front in place across the area today. The front will sink south toward Carolinas tonight through Sunday...as a slow moving area of low pressure tracks along the southeast coast Sunday and Monday. This system will bring periods of moderate to heavy rainfall to the region Sunday through early next week. && .NEAR TERM /THROUGH TONIGHT/... FYI...Preliminary results from the storm survey in the Colonial Beach area shows mainly straight line wind damage. Official statement to be issued later today once survey is completed. Tweeked temps a bit more as readings are approaching 80 at ORF with steadying readings in the mid 50s across the eastern shore. Steady or slowly falling readings west of the bay and north of the boundary this afternoon. Quite a differential heating boundary for convection to fire up on, so went ahead and bumped up the thunder chcs across southern most VA and NE NC zones after 18Z. SPC now has a SLGHT risk across south central zones from AVC-AKQ- RWI. Large hail and damaging winds main threat, minimal tornado threat. PVS DSCN: This is the kind of day that makes one go gray fast. Continue to tweek temps per rises on south side of boundary while steady or falling temps north of the front which is crntly located near a fvx-ptb-phf line. Could easily see readings at ORF drop 10-15 degrees once bndry moves thru and the wind turns NNE. Radar loop showing a "lull" in pcpn coverage but do expect that to fill in over the next few hrs. Some fog developing in wedge cooled airmass to the north but will leave fog out of grids for now and re- evaluate for 4 PM update. After viewing some 12Z data, latest thinking here is that any severe threat gets shunted south into NC by 21Z as the front sags to near the VA/NC border. More concern is the locally heavy downpours possible given the combo of any TSTMS along and south of the bndry and the moisture associated with the wave approaching from the SW. Again, stdy or falling temps to btwn 55-60 north, highs in the 70s to nr 80 south but quickly falling after fropa. PVS DSCN: Showers slowly settle south across NC this evening, with a brief lull in showers once again overnight as we await upper trough swinging east toward the region late tonight. This should add up to scattered to numerous showers through the overnight with plenty of low clouds and patchy fog developing. Lows in the 40s out in the piedmont, low to mid 50s along the coastal plain. && .SHORT TERM /SUNDAY THROUGH MONDAY/... A wet period ahead for the latter half of the weekend into at least Monday night with rainfall amounts between 1-3 inches through Monday, highest (2-3 inches) over the piedmont. Broad upper level low currently over the Plains into the Mid- Miss Valley will pivot SE into the deep south. The system then takes on a neg tilt as it deepens Sunday, spawning a surface low along the sern coast, which then is progged to get cut off from the main flow and drift ivof the Gulf Stream wall into the middle of next week. Models show both spacial and timing differences with the moisture fields but the jist of the forecast will be for waves of Atlantic moisture to rotate inland resulting in periodic showers (embedded tstrms especially over the sern coastal zones). Locally hvy downpours psbl starting Sunday and Sunday night. Meanwhile, high pressure to the NE results in a cool in-situ wedge setting up over the piedmont, along with areas of fog. Hydro wise, no flood headlines expected 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. QPF is mainly a blend of the WPC preferred ECMWF/UKMET along with going forecast continuity...resulting in 2-3" west of i-95 to 1-2" to the east. Locally higher amounts are likely owing to developing convection. Highs mainly in the 50s to near 60 Sunday...lower to middle 50s inland...to mid 60s/nr 70 SE Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 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 /18Z 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...MAM NEAR TERM...MPR/MAM SHORT TERM...MPR/MAM LONG TERM...MAS AVIATION...AJB MARINE...SAM TIDES/COASTAL FLOODING...

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