Area Forecast Discussion
Issued by NWS Wakefield, VA

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094 FXUS61 KAKQ 201911 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 311 PM 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 AM WEDNESDAY MORNING/... Morning analysis indicating double barreled sfc low pressure with one center over Ern NC and the other over SW VA, and 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 lifting across the area with rain continuing from central VA to the Ern Shore. 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 through midday. 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 AM WEDNESDAY MORNING THROUGH FRIDAY/... 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 /FRIDAY NIGHT THROUGH TUESDAY/... Region remains influenced by large scale upper trof through most of the extended period. Area is between systems Friday night and most of Saturday. A shortwave trof will be approaching from the west Saturday night, and move across the area on Sunday. 12Z GFS/ECMWF are at odds with regard to how far north precip gets with this shortwave. Have gone with a blended solution, which gives a chance of rain/snow across much of the area. Shortwave moves offshore Sunday night, with ridging surface and aloft gradually building into the region Monday through Tuesday. Overall, cold high pressure building in from the the NW will provide a continuation of below/much below normal temperatures for much of the forecast period. For temperatures, Highs Sat around 50F inland...m40s at the coast. Lows Sat night generally 30-35, with some upper 30s NE NC. Highs Sun in the 40s to around 50 F, and Mon mid to upper 40s N/DELMARVA to mid 50s southern portions of interior NE NC. highs Tuesday around 50 Lower MD Eastern Shore to the upper 50s interior NE NC. Lows Sunday night/Monday night in the low to mid 30s. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Low pressure is located off the VA Capes as of 18z, with another area of low pressure situated over the srn Appalachians. Meanwhile, high pressure centered N of the Great Lakes is ridging swd through the Piedmont. Rain continues over the Ern Shore, with some lingering areas of light rain and drizzle from central to SE VA. IFR/LIFR cigs prevail with 2-4sm vsby in rain. A NNE wind is generally 10-15kt with gusts of 20-25kt, with the exception of SBY where a NE wind of 20-25kt is gusting to 30-35kt. IFR cigs should prevail this aftn and evening although there could be occasions where cigs lift to MVFR around 1.0-1.5kft. The next area of low pressure arrives later tonight into Wednesday with IFR/LIFR conditions continuing. Rain arrives later tonight and transitions to snow at RIC between 09-12z and at SBY 14-16z. A N wind of 10-15kt with gusts to around 20kt is expected. Rain should become snow at PHF after 18z, and a mix or change to all snow briefly is possible at ORF/ECG later in the day. Snow potentially lingers at SBY Wednesday evening. Otherwise, drier conditions arrive later Wednesday night, with dry and VFR conditions prevail Thursday and Friday. Low pressure arrives from the W Saturday. && .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...Coastal Flood Advisory from 6 PM this evening to 4 AM EDT Thursday for MDZ024-025. Wind Advisory until 8 PM EDT this evening for MDZ024-025. High Surf Advisory from 6 PM this evening to 8 PM EDT Wednesday for MDZ025. Winter Storm Watch from Wednesday morning through Wednesday evening for MDZ021>025. NC...Coastal Flood Advisory from 6 PM this evening to 4 AM EDT Thursday for NCZ102. VA...Coastal Flood Advisory from 10 PM this evening to 8 AM EDT Thursday for VAZ089-090-093-096-524. Coastal Flood Advisory from 6 PM this evening to 8 AM EDT Thursday for VAZ078-084>086-095-097-523-525. Coastal Flood Advisory from 6 PM this evening to 4 AM EDT Thursday for VAZ098>100. Winter Storm Watch from Wednesday morning through Wednesday evening for VAZ099. Wind Advisory until 8 PM EDT this evening for VAZ099. High Surf Advisory from 6 PM this evening to 8 PM EDT Wednesday for VAZ099-100. 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/MAM/TMG NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...MAM/WRS AVIATION...AJZ/LKB MARINE...AJB TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.