Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 240818 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 418 AM EDT SAT SEP 24 2016 .SYNOPSIS... A backdoor cold front drops south across the region Today. High pressure tracks across Southeast Canada early next week. A second, stronger cold front will cross the region later Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Latest analysis features strong 1026+mb high pressure over Ontario into the Upper Great Lakes. Subjective wx analysis places weak cool frontal boundary from Southern New Jersey back into the Mason-Dixon line and the lower Ohio Valley early this morning. Meanwhile, weak ~1018mb high pressure is in place across the region. Aloft, prominent upper level ridging remains in place, centered across the mid-south and Mississippi River Valley. this is keeping PW values suppressed in the 1-1.25" range across the region per early morning Blended TPW sat product. Have noted some areas of ground fog, dense in spots along the southern tier of the forecast area. Will likely have to handle with a round of targeted statements this morning, but otherwise expect fog and any lingering stratus to get mixed out quickly after sunrise this morning. After fog scours out, expect a partly to mostly sunny start, with clouds quickly increasing across the northern tier of counties from Late Morning through the aftn as the front drops across the area. Winds shift to the N-NE during this timeframe. High-res models resolute in showing an area of rather shallow lift along the front as it drops across the southern half of the area from late aftn through about midnight. Have accordingly kept the forecast dry through the day, introducing some sct showers tonight, mainly across the piedmont and I-85 corridor. QPF will be minimal with still relatively dry air aloft. and only weak isentropic lift. Thickness tools and CONShort/HRRR basically identical wrt high temps, producing highs in the mid to upr 70s eastern shore...low to mid 80s RIC metro...and mid to upper 80s far SW zones. Front drops south of the area late tonight, with sct showers along the boundary likely lingering into the morning hours. Clouds will be on the increase post-frontal, especially inland with post frontal nne flow as high pressure ridges down and cool air wedge begins to set up. Accordingly beefed up sky cover tonight and into Sunday. Lows Sat night in the mid 50s north to mid 60s south. && .SHORT TERM /SUNDAY THROUGH MONDAY/... Front continues to push south into the Carolinas Sunday in response to high pressure sliding across Southeast Canada. This high extends south across the Mid Atlantic Region Sunday and Sunday night. Have again increased SKY cover to account for increasing low level moisture/ongoing weak isentropic upglide. Overcast conditions and pockets of light rain or drizzle remain a good bet along and west of the I-95 corridor. Pops remain only in slight chc range with minimal chances for measuring pcpn. Nonetheless, drizzly and overcast inland...a mix of some sun along with clouds along the coast. Highs Sun 70-75. Lows Sun night in the mid 50s to lwr 60s. Cooler readings in the lower 50s with clearing sky across Eastern shore. Upper ridge pivots to the coast on Monday, before sliding offshore Monday night. At the Sfc, high pressure moves north of New England Monday with the next front approaching from the west during the afternoon. Across the piedmont, cool air wedge will hold on one more day...with lingering clouds onshore flow and clouds maintaining cool temps. Monday highs generally in the low to mid 70s, upper 70s to around 80 along the SE coast. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Strong cold front progged to drop into the region Monday night ahead of a potent northern stream trough. Latest deterministic and ensemble guidance in good agreement with pushing the front across the region late Monday night through Tuesday. Moisture increases along the front with precipitable waters climbing above 1.75 inches. Instability progged to be marginal ahead of the front due to cloud cover and poor lapse rates, However, will keep mention of slight chance thunder in the area of highest showalter values (elevated instability) and shear around 40 knots. Both GFS and ECMWF models push the front across the region rather quickly Tuesday with much of the area seeing a decent chance for shower. Have capped at high end chance. High pressure builds in from the west late Tuesday and Tuesday night. Will linger POPs over the southeast half of the forecast area, but expect much of the precip to push offshore by late Tuesday night. High pressure prevails through the end of the week and into the weekend. Temperatures will average close to seasonable averages, with highs Tuesday ranging from the mid 70`s northwest to around 80 southeast. Highs Wednesday through Friday generally in the 70`s with lows in the 50`s, expect in the 60`s southeast. Based on the latest statistical guidance, the Piedmont may see some readings in the 40`s Thursday morning. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... Mostly clear skies this morning as weak high pressure slides over the area. Given light winds and still wet grounds, noting areas of low Stratus/fog across the SE coastal plain, impacting KECG, and eventually KSBY and KPHF after 08z. Expected low clouds/fog will scour out quickly after sunrise this morning, improving quickly from LIFR/IFR at ECG to MVFR/VFR after 14z. Thereafter, primarily VFR conditions expected. A backdoor cold front drops across the area through the day Saturday...primarily spreading widespread high clouds across the area during the day. Given the abundant/recent rainfall from the past several days and persistent onshore/ne winds, expect SCT cumulus to develop during the aftn...especially near coastal sites. KSBY will likely experience MVFR cigs given frontal timing, and Hi-res models continue to support VFR farther inland. Could see some Sct showers west of KRIC after 21z this aftn, but minimal support for pcpn at terminals with plenty of dry air in place aloft. The front pushes south of Albemarle Sound after midnight Saturday night with stronger central high pressure sliding across Southeast Canada and building down into the Mid Atlantic Region through Sunday night before sliding off the New England coast early next week. Areas of fog and some low stratus expected once again across the southern terminals late Tonight into early Sunday morning. Outlook... Cigs trend back toward VFR for most locales along the coast as cool air wedge sets up across the piedmont. Lingering low clouds/light rain possible at KRIC and west. && .MARINE... Weak pressure gradient observed over the waters early this morning as a cold front drops into the northern Mid-Atlantic region. Winds are generally out of the west-southwest at or below 10 knots. Seas 3- 4 feet and waves 1-2 feet. The weak front drops southward over the waters today, with flow becoming northernly. 850mb temps dip slightly behind the front, but a lack of low level cold air advection and weak gradient winds expected to keep winds sub-SCA this afternoon. Hi-resolution guidance has trended lower on speeds as well. Waves build to 2-3 feet late morning/early afternoon. For the coastal water, distant tropical cyclone Karl will aid in building seas to 4-5 feet this afternoon through tonight. Have raised SCA headlines for all coastal waters as a result. Expect a few gusts to around 20 knots, so have opted against SCA for hazardous seas. High pressure builds southward over the waters tonight, with northernly winds diminishing to around 10-15 knots. Seas subside to 3-4 feet Sunday afternoon. Waves 1-2 feet. The next cold front approaching from the northwest will shift winds back to the south to southeast Monday. Marginal southerly SCA conditions are possible ahead of the front late Monday and Monday night behind a lifting warm front. The front progged to reach the waters Tuesday morning, pushing offshore Tuesday afternoon. SCA conditions expected behind the front as a significantly cooler air mass and strong high pressure builds in from the northwest. && .HYDROLOGY... The Cashie River at Windsor continues to fall but remains in the moderate flood range. The river is forecast to slowly fall below flood stage late Sunday night. See FLSAKQ for details. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 10 AM EDT Sunday for ANZ650-652-654-656-658. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MPR/MAM LONG TERM...LKB AVIATION...MAM MARINE...LKB HYDROLOGY... is the U.S. government's official web portal to all federal, state and local government web resources and services.