Area Forecast Discussion
Issued by NWS Wakefield, VA

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302 FXUS61 KAKQ 251825 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 225 PM EDT Tue Apr 25 2017 .SYNOPSIS... Low pressure tracks across the North Carolina coastal plain today...then continues northeast along the Mid Atlantic coast tonight and Wednesday. High pressure builds into the area Thursday. A cold front stalls north of the region on Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Adjusted grids a bit this aftrn per crnt conditions. Dry slot has quickly shut off pcpn in most areas but expect addntl shwrs to develop as dytme heating combines with the upr level energy. Kept thunder confined mainly along the coast and areas that has seen sun. Temps range from the 60s NW...70-75 SE. PVS DSCN: Tropical moisture plume and associated showers now lifting north northwest as the system continue to wrap around the upr level low to the south. Of note is the dry slot noted by sct-bkn mid level clouds across ne nc/sern va. Still have the upr level systm to deal with this afternoon so will continue with the cat to likely pops for the next few hrs slowly ramping down toward evening. Thunder chcs continue across the south and east as the system tracks ne, especially in areas that do get some partial sunshine. Highs arnd 60 NW to mid 70s SE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... Upper/surface low pressure lifts along the Mid-Atlantic coast this evening, and then north of the local waters late tonight. Wrap around moisture keeps chance to likely POPs across the northeast local area through late tonight. Given the recent rainfall and saturated soils, have included patchy fog across much of the region. However, cloud cover and light winds will limit the overall coverage. Lows tonight generally in the mid to upper 50`s. Low pressure lifts along the Northeast coast Wednesday as an upper level ridge builds over the region. Thermal soundings indicate mid level moisture trapped beneath a strong subsidence inversion aloft, which will help keep clouds around through the day. However, given the late April sun, anticipate several breaks in the clouds inland. Soundings also indicate very little mixing, but given height rises and warming low level temps/thicknesses, forecast highs are generally in the mid to upper 70`s. Cooler along the coast. Mild Wednesday night under a partly clear to mostly clear sky. Lows forecast in the upper 50`s to low 60`s. Ridge axis slides offshore ahead of an approaching cold front Thursday. Increasing return flow and 850mb temps around +14 to +16C (around +1 standard deviation) result in warm (and dry) conditions with highs generally in the 80`s. Cooler along the coast. Plenty of sunshine expected. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Long term period will feature above normal temps with mainly dry wx. For Thu night/Fri, deep SWly flow continues across the eastern seaboard as an upper-level ridge then builds in through the weekend allowing for warm temps and dry wx as most of the energy aloft will stay N and W of the local area. At most a 20% chance of a late day shra/tstm Fri and Sat. High temps Fri through Sun in the 80s, pushing near 90 Sat and Sun. Low temps in the mid/upr 60s. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Low pressure continues to move northeast across the region this afternoon before finally pushing offshore tonight. Widespread IFR ceilings continue over mainly northern portions of the area, including RIC and SBY, this afternoon. Closer to the center of low pressure over southeast portions of the region, some temporary clearing and mainly VFR ceilings are anticipated. Radar trends have shown diminishing coverage in rain showers this afternoon, but model guidance continues to hint at the redevelopment of showers across eastern portions of the area. Stratus and widespread IFR ceilings are expected to redevelop overnight as moisture wraps around the backside of the low pressure. Guidance has also been persistent with the development of patchy fog tonight and into tomorrow morning. Included MVFR visibilities for tonight, but it is possible IFR visibilities may develop in a few locations. Conditions will improve during the day on Wednesday, returning to VFR Wednesday afternoon. Light easterly flow is expected to continue through this afternoon and evening. Winds will shift to the W/NW as the low departs the area tonight and Wednesday. Winds remain light on Wednesday, generally 5-10 knots. Outlook: Aviation conditions improve through the day on Wednesday with VFR expected to return to the area. A shower or thunderstorm will be possible during the day on Friday, but otherwise, VFR and dry conditions should dominate the extended period. && .MARINE... Current analysis indicating sfc low pressure centered just S/SW of Cape Hatteras, with E/NE flow ongoing across the local marine area. Thus far, winds have been at SCA levels but have remained below Gale criteria. Pressure falls have not been that significant and therefore will be relying on mixing the stronger winds aloft to the surface. High res models depict a short period with Gale force gusts possible for the lower Bay and southern coastal waters through mid morning, with higher winds lingering across the northern coastal waters into early aftn. Overall, this event looks marginal but will maintain continuity and keep the Gale Warning in effect through 10 am S to 1 pm N. SCA headlines remain in effect for the upper James/York/Rappahannock Rivers where gusts up to 30 kt are expected. Seas up to 8-12 ft, with a high surf advisory remaining in effect for 8-9 ft waves in the surf zone. No cold air surge in the wake of this system later today and tonight, so aside from high seas lingering for the coastal waters/mouth of Bay, expect rapidly improving conditions later today and tonight. Seas should fall off to below 5 ft later Wed/Wed night. Winds begin to shift to the S Thu/Fri w/ sub-SCA conditions to prevail. && .TIDES/COASTAL FLOODING... Current tidal departures are averaging around 1.5 to 1.75 feet in the lower Bay and southern coastal waters due to ongoing onshore flow, while departures farther N are genly 1 ft or less. Have raised coastal flood advisories for zones adjacent to the lower Bay/James/York River, as well as the VA eastern shore. This will be for the upcoming high tide later this morning. More uncertainty exists farther N in the Bay up the coast and have continued with another round of statements for these areas for now. Surprisingly, despite continued onshore flow, currents data from Cape Henry Channel shows that water has been exiting the Bay at the same rate that it has been coming in/ i.e. piling of water into the Bay has been fairly minimal so far. ESTOFS and CBOFS data suggest this will change later today through tonight with the potential for water to become trapped in the Bay and for eventual minor flooding for the mid/upper Bay by tonight. May need to raise a coastal flood advisory later today for some of these locations, but did not do this yet because of how the winds associated with this system have genly underperformed so far. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...High Surf Advisory until 7 PM EDT this evening for MDZ025. NC...High Surf Advisory until 4 PM EDT this afternoon for NCZ102. VA...High Surf Advisory until 4 PM EDT this afternoon for VAZ098. High Surf Advisory until 7 PM EDT this evening for VAZ099-100. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ634. Small Craft Advisory until 4 PM EDT this afternoon for ANZ632. Small Craft Advisory until 7 AM EDT Thursday for ANZ650-652- 654. Small Craft Advisory until 7 PM EDT Wednesday for ANZ656-658. && $$ SYNOPSIS...ALB/MPR/SAM NEAR TERM...MPR SHORT TERM...SAM LONG TERM...MAS AVIATION...AJB MARINE...LKB/MAS TIDES/COASTAL FLOODING...

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