Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 251747 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 147 PM EDT SUN SEP 25 2016 .SYNOPSIS... A backdoor cold front settles across the Carolinas today. High pressure will build across New England...ridging south into the area through early Monday. A second and stronger cold front will cross the region Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Late morning MSAS shwoing the cold front across southern NC with sfc high pressure north of Lake Ontario. Drier air nosing down the coast has resulted in mainly clr skies across the Delmarva, a buffer zone ivof Ches Bay sct-bkn SC with bkn-ovc SC across the piedmont. 12Z soundings / high res data continue to show weak shallow isentropic lift and onshore flow keeps the bkn-ovc sky coverage across the piedmont...variably cloudy ivof the bay and pt to mstly sunny ern shore areas this afternoon. Feeling more like fall than recent days with highs in the low to mid 70s. PVS DSCN: After some short-lived clearing early tonight, clouds re-develop by midnight and through the overnight as the cool air wedge is reinforced by renewed isentropic lift, underneath upper ridge axis nudging in from the west. Sky cover ranges from overcast with areas of light rain or drizzle well inland across the piedmont to partly cloudy along the VA coast over to the MD Eastern Shore. Look for chilly early morning lows from around 50 MD Eastern Shore...to mid 50s to around 60 central and south (mid to upper 60s along the SE coast. && .SHORT TERM /MONDAY THROUGH TUESDAY/... High pressure moves offshore of the New England coast on Monday as the next front approaches from the west Monday afternoon. Flattening of upper ridge will slow the advance of the front, and serve to break down the cool air wedge slowly from NW to SE Monday afternoon as the sfc high slides offshore. However, clouds should hold firm across the piedmont through much of the day, resulting in another mostly cloudy to overcast day Monday, variably cloudy along the coast. Highs in the mid to upr 70s. A strong cold front still on track to cross into the region late Monday night ahead of a potent northern stream trough. Moisture increases along the front with PW`s climbing above 1.75 inches along with marginal instability per Showalter values trending around 0 after 00z/Tue. Pcpn enters the region from the NW with highest pops Monday evening, spreading east as best forcing nudges from sw to ne Tuesday morning. Lows Mon night in the mid 60s. Models show possible weak s/w energy riding east along the boundary Tuesday. This will likely enhance pcpn and allow it to linger a bit longer especially along coastal sections. Likely pops linger across the Se zones through Tue. Kept thunder chcs in as well, again with modest instability lingering. Highs Tuesday in the low to mid 70s. QPF generally between 1/2 to 3/4 inch. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Medium range guidance continues to indicate anomalous heights over Canada through the period, as well as over the western Atlantic. A deep/anomalous upper low drops over the eastern Great Lakes region Wednesday, under the upper ridge. Ensemble and deterministic guidance continues to struggle with a more progressive versus blocked flow over the eastern CONUS. The result is a relatively low confidence forecast, but have trended more toward GFS/GEFS solutions. Tuesdays cold front progged to stall along the coast in deep layer southwesterly flow across the Mid-Atlantic. POPs taper off inland Tuesday night, with chance POPs remaining across the southeast forecast area. A series of upper level disturbances will lift along the frontal boundary Wednesday. The combination of waves lifting along the front and strong upward vertical motion will bring solid chance POPs back to the southeast local area and slight chance to low end chance inland. The upper low locates in the vicinity of the Mid Atlantic region Thursday. While the best moisture pushes offshore, will keep mention of slight chance to chance POPs Thursday and Thursday night to account for uncertainty and potential light rain. Thereafter, the upper low likely begins to slowly lift northeastward as the upper ridge over the western Atlantic begins to break down. With the upper low lifting away from the region Friday and Saturday, large scale subsidence over the region will result in a drying trend. Will keep chance POPs northeast Friday and retain silent POPs on Saturday. Slightly below normal temperatures forecast through the period, with highs generally in the low to mid 70`s. Lows range from the low to mid 50`s inland to mid 60`s along the coast. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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Drier air from the north continues to filter south along the coast this afternoon. This is resulting in VFR conditions with only SCT SC along the Delmarva, SCT-BKN SC between 4-5K ft ivof the Ches Bay, BKN-OVC SC between 3-5K ft across the piedmont. Nearest MVFR cigs are across the mts. Models now showing only SCT clouds along the coast tonight with differing solutions for RIC. Given the lgt onshore flow and position of the high, decided to keep a BKN SC deck around 4K ft at RIC through the night with SCT SC elsewhere. Fog not expected to be a big issue tonight but can`t rule out some ptchy MVFR VSBYS toward sunrise in areas where it does CLR. Any pcpn is expected to be confined to the mts. OUTLOOK...The next chance for widespread precipitation arrives Monday night into Tuesday ahead of a strong cold front. Showers will linger through the mid week period as an upper level low tracks across the region.
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&& .MARINE... Cold front has located south of the waters early this morning, as high pressure builds in from the north. North to northeast winds of 10 to 15 knots observed over the waters, with occasional gusts of 20 knots over the southern coastal waters. Have dropped SCA headlines for the lower Chesapeake Bay. Seas remain elevated thanks to distant tropical cyclone Karl and onshore flow, ranging from 3 to 5 feet. SCA headlines remain in effect for the coastal waters. Based on the latest guidance, have extended headlines through 1 pm this afternoon. Thereafter, seas subside to 3 to 4 feet. This mornings cold front lifts back to the north Monday as a cold front approaches from the northwest. Flow becomes south to southeast with marginal SCA conditions possible late Monday into Monday night. The front pushes across the region Tuesday, likely stalling along the coast Tuesday night and Wednesday. A weak pressure gradient progged over the region, but a cooler and drier air mass may result in at least marginal SCA conditions late Tuesday night. An upper level low is progged to drop into the region Wednesday and Thursday, resulting in unsettled weather conditions through the end of the week. Flow generally out of the north. && .HYDROLOGY... The Cashie River at Windsor remains in minor flood stage. The river is forecast to slowly fall below flood stage by late this afternoon. See FLSAKQ for details. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ656- 658.
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&& $$ SYNOPSIS...MAM NEAR TERM...MPR/MAM SHORT TERM...MPR/MAM LONG TERM...SAM AVIATION...MPR MARINE...SAM HYDROLOGY...

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