Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 121754 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 154 PM EDT Sat Aug 12 2017 .SYNOPSIS... A cold front will slowly approach from the northwest this afternoon, and slowly sag south through the local area this evening. Numerous showers and scattered thunderstorms can be expected through this evening. The front will stall across North Carolina on Sunday, and will push back north Sunday night into Monday as a wave of low pressure moves along the boundary. Additional areas of low pressure will move along the front into Tuesday, with high pressure finally building north of the region by Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Ongoing convection has been persistent and excessive invof the eastern shore (esp over MD), and has now finally waned/pushed offshore. An area of 4-8" of rain in the vicinity of SBY prompted Flash flood Warning earlier that has now been replaced with a long duration flood warning into this evening (see FLWAKQ for details). Scattered showers/tstms persist over the remainder of the CWA. Partial clearing has developed over some of southern/SE VA, though with the airmass unstable as heights aloft fall this aftn, expect clouds and showers/tstms to rapidly fill back in after 18Z. Will continue the flash flood watch for far SE VA-NE NC due to recent rainfall past few days and as this will tend to be the axis of the heaviest additional rain for the late aftn into the evening timeframe. Adjusted current temperatures/dew pts to latest observations, but overall made minimal changes, with highs mainly in the 80 to 85 degree range. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... The cold front crosses the FA tonight. Deepest moisture gets shunted offshore and S...but enough lingering moisture to keep likely pops going across the E...tapering off to chc PoPs elsewhere. Lows ranging from the u60s NW to the m70s SE VA-NE NC. That frontal boundary will linger just S of the local area or near the SE VA/NE NC border Sun afternoon thru Mon...maintaining chc to likely PoPs across srn VA-NE NC into Sun night w/ PoPs aob 15% central/N. PoPs remain 30-60% from srn VA to NE NC Mon into Mon evening as the boundary remains nearly stationary. Highs Sun and Mon 80-85F. Lows Sun night in the m-u60s N to 70-75F S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... The period begins with more wet weather expected from Monday night into early Wednesday as a frontal boundary remains stalled across the Mid-Atlantic States and the Carolinas. The biggest question has been the location of the front which the GFS and ECMWF have had a hard time reaching a consensus as run to run consistency has waffled the front from over us to areas south of the forecast area. The 12z ECMWF run of the models has the front and associated surface wave lifting over the Mid-Atlantic states while in the 12 GFS the front remains south of the area and holds the bulk of the rain further south over the Carolinas. This is a flip from yesterdays runs. So for now, have generally played a scenario where the front stall near the area and the wave of low pressure moves along the front and should impact much of the area on Tuesday. Have added likely pops to SE VA and NE NC as this area appears to have the best chance of rain on Tuesday/Tues night. By Wednesday...the front will get drug south of the area as the wave moves off the coast. This will allow high pressure to build into the area as the flow aloft turns nw as the upper trough swings through the area. This high will provide a couple dry days before the next boundary crosses the area on Friday as the upper ridge over the lower MS Valley and Southern Plains builds eastward. There could be some scattered convection along this warm front moves through the area. For temperatures...did go a little cooler on Tuesday with the idea of clouds and rain, but without having a better handle on the frontal position could easily see either much cooler temps, in the 70s, than shown or perhaps if the front lifts further north, it could be more int he mid to upper 80s. Once the front clears should see drier conditions and initially having temps in the low to mid 80s with a warming trend into the second half of the work week with readings back toward near normal values in the mid to upper 80s. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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First round of widespread convection has moved offshore. However, breaks in the BKN-OVC SC cloud deck has allowed heating to take place over the past few hours leading to the additional convection developing. Thus, have opted to go with VCSH/VCTS with a tempo group for the next 2-4 hrs. Next round of convection will be associated with the actual cold frontal passage later this evening. Thus, expect sct pcpn with MVFR cigs through the night. WInds shift to the north behind the fropa but still expect low clouds to persist Sunday morning. OUTLOOK...Unsettled conditions with periodic convection continues through Tuesday as the boundary stalls across the region with a series of disturbances pushing across the area.
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&& .MARINE... No headlines necessary with this forecast package. High pressure remains well offshore today as a cold front slowly approaches from the west. Expect southerly flow up to 10-15 kt with 1-2 ft waves over the Bay and 2-3 ft seas over cstl wtrs. The front drops into the area tonight then slides south near the Carolina coast Sunday, remaining near there through early to mid next week. A prolonged period of weak onshore flow is expected during this timeframe with seas up to 3-4 ft. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...Flash Flood Watch until 8 PM EDT this evening for NCZ012>017- 030>032-102. VA...Flash Flood Watch until 8 PM EDT this evening for VAZ092-093- 095>098-523>525. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...ALB/TMG LONG TERM...ESS AVIATION...MPR MARINE...MAS is the U.S. government's official web portal to all federal, state and local government web resources and services.