Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 201159 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 759 AM EDT Tue Mar 20 2018 .SYNOPSIS... Low pressure will redevelop from the southeast Virginia coast to the North Carolina coast late this morning, and will intensify while tracking northeast tonight and Wednesday. High pressure gradually builds into the area late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Early morning analysis indicating double barreled sfc low pressure from SC to SW VA, with a potent mid/upper level low centered from the lower OH Valley to the mid/lower MS Valley. Strong area of deep lift and overrunning moisture is pushing through the local area early this morning and have PoPs of 80-100% through 15Z for the entire CWA. The rain is locally heavy but genly not excessive and will avg from 0.75" to 1.50" through this aftn. This is all rain (no concern for any snow/sleet through the aftn). The sfc low deepens as it tracks across the VA Capes later this morning. This will result in windy conditions (NE wind) along the Atlantic coast of the VA/MD Ern Shore where a wind advisory in in effect mainly for areas from Chincoteague to Ocean City. The low then lingers off the coast this aftn as weak high pressure tries to nudge in from the north. This will result in the wind becoming more northerly during the aftn. GFS/NAm depict main region of lift and moisture through the DGZ pushing off to the NE from late morning into early aftn. Low clouds and light rain or some drizzle will remain but QPF amts this aftn will be minimal except over the far NE where likely PoPs will persist. Most of the CWA will only have highs in the 40s today (close to current values), but highs in NE NC and far SE VA will be in the 50s to lower 60s. Temperatures will likely fall off later in the aftn in these locations as winds shift more to the N and increase. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... The complex system will continue to impact the region tonight into Wednesday. There is still some uncertainty on how the system evolves tonight into Wednesday. However, the 20/00z GFS/NAM/ECMWF continue to depict a deepening of the surface low close enough to the coast with the potential for frontogenetic banding over northern/NE portions of the CWA. Given enough model spread and the potential for banding well inland, have expanded the winter storm watch to to also include Accomack VA and the northern Neck counties of VA. Will likely need a round of winter wx advisories beginning late tonight or Wed morning, but given the uncertainty in amounts and with just rain expected through the evening commute, opted to allow dayshift to evaluate for exactly where to draw these headlines. The upper level system pulls in enough cold air to allow a transition to snow late Tuesday night into Wednesday. Chc to likely PoPs Tuesday evening ramp up to likely to categorical everywhere after midnight through midday Wednesday as the forcing from the upper level system taps into moisture. Thicknesses suggest a mixed/rain and snow event across the Piedmont Tuesday night changing to all snow, and rain/snow Tuesday night changing to all snow around daybreak Wednesday for central VA. A cold rain over the Delmarva will change to snow Wednesday morning, and a cold rain for SE VA/NE NC could mix with some snow Wednesday aftn. The current forecast is for 1-3" of snow from the NW piedmont across central VA, with 2-5" for the Nrn Neck and the VA Ern Shore, with the potential for 3-6" over the MD Ern Shore. Elsewhere, expect an inch or less with little to no accumulation for far SE VA/coastal NE NC. Lows tonight range from 30-32F NW to the upper 30s SE, followed by highs Wednesday in the mid 30s where snow falls to the upper 30s/low 40s where rain prevails. Highs in south central VA may rise to around 40 F later in the aftn as the precip intensity diminishes. Drier air arrives Wednesday night into Thursday as the system pulls to the northeast. Partly to occasionally mostly cloudy under the upper trough. Lows Wednesday night range from the mid/upper 20s NW to the low 30s SE, with highs Thursday in the mid to upper 40s, possible cooler over the MD Ern Shore depending on snowfall Wednesday. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Remained close to WPC grids for the late week into early next week. Overall, cold high pressure building to the NW will provide a continuation of (much) below temperatures for much of the forecast period. After a cool, dry day on Friday, rain chances increase once again ahead of next system, which develops across the central plains on Fri/Friday night...then tracks east, undercutting the omega block in place over the northern tier of states through the weekend. Remaining partly to mostly cloudy through the weekend, with rain chances to increase later Sat into Sat night before becoming more widespread on Sunday. For temperatures, Highs Fri/Sat around 50F inland...m40s at the coast. Lows Fri night in the l30s inland...u30s-around 40F at the coast. Highs Sun in the 40s to around 50 F, and Mon 40s N to mid 50s S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Rain will persist through midday may be heavy at times through 15z. Ceilings will be mostly IFR to occasional LIFR near the coast. Winds will be mostly NE to E at 10-15 kt inland, but gusting to 25-30 kt near the coast. Winds shift more to the N after 18Z and may see cigs improve a bit to MVFR levels inland with rain becoming light/spotty except at KSBY. Rain, gusty winds, and IFR conditions will generally prevail again later tonight as next round of widespread rain moves back tonight. Outlook: More IFR/LIFR flight restrictions will prevail on Wed. Rain will be changing to snow from 12-18Z at area terminals. There could be some accumulations of an inch or two, possibly more at KSBY. Gusty winds buffet the coast Wed as well. Drier/VFR Thu-Fri. && .MARINE... Current observations show E/SE winds of 15 to 25 knots over the waters as low pressure slides south of the area. Seas range from 3 to 4 feet and waves range from 2 to 4 feet. Small Craft Advisories are now in effect for all of the waters. A Gale Warning remains in effect for the coastal waters north of Cape Charles. Pressure gradient will continue to tighten over the region this morning between approaching surface low pressure from the west and surface high centered over Ontario. Low pressure is expected to move offshore near the VA/NC border later this morning and redevelop off the coast. Model guidance continues to show the highest wind potential mainly north of Cape Charles, thus left the headlines unchanged. Wind gusts could briefly approach as high as 40 to 45 knots from Chincoteague north Tuesday afternoon as the low deepens. Wind gusts could also approach 35 knots over the northern Bay later this morning, especially at the elevated stations. Another surface low develops off the coast Tuesday night into Wednesday allowing for another round of Gale force conditions over the northern waters and SCA conditions over the remainder of the waters. Seas also build quickly Tuesday into Wednesday with seas reaching 8 to 12 feet on the coastal waters. Low pressure moves well off the coast by late Wednesday/Thursday morning allowing for conditions to slowly relax. Northwest flow continues into Friday when high pressure finally settles back over the area. Seas will likely remain elevated at or above 5 feet for coastal waters through at least Thursday. Another low pressure system may impact the waters by Sunday. && .TIDES/COASTAL FLOODING... Tidal departures build this evening through Wednesday and there will be the potential for at least minor coastal flooding for locations adjacent to the lower Bay and the Atlantic coast. Went ahead and issued a Coastal Flood Watch for coastal portions of Worchester County where guidance continues to indicate the potential for Moderate flooding Wednesday. Expect for tide departures to run from 2 to 3 feet above normal tide around times of high tide. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Wind Advisory until 8 PM EDT this evening for MDZ024-025. Coastal Flood Watch from this evening through late Wednesday night for MDZ024-025. Winter Storm Watch from Wednesday morning through Wednesday evening for MDZ021>025. NC...None. VA...Wind Advisory until 8 PM EDT this evening for VAZ099. Winter Storm Watch from Wednesday morning through Wednesday evening for VAZ099. Winter Storm Watch from Wednesday morning through Wednesday evening for VAZ075>078. MARINE...Gale Warning until 2 PM EDT Wednesday for ANZ650-652-654. Small Craft Advisory until 8 PM EDT Wednesday for ANZ630>638- 656-658. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...AJZ/LKB LONG TERM...MAM AVIATION...LKB MARINE...AJB TIDES/COASTAL FLOODING...AKQ is the U.S. government's official web portal to all federal, state and local government web resources and services.