Area Forecast Discussion
Issued by NWS Wakefield, VA

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736 FXUS61 KAKQ 210756 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 356 AM EDT Fri Apr 21 2017 .SYNOPSIS...
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A cold front will approach from the northwest today, pushing across the area late today and tonight. The front will stall across North Carolina and offshore Saturday through Sunday. Low pressure will track eastward along the frontal boundary across Tennessee and into the Carolinas Saturday through Sunday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A cold front is making its way across the Northeast and Ohio Valley this morning. Ahead of the boundary, mild temperatures are in place locally with a mainly clear to partly cloudy sky. The only exception is some locally dense fog that has developed from Salisbury to near Ocean City which should linger til just after sunrise. With SW winds in place ahead of the approaching front and at least a partly sunny sky, expect temps to warm into the mid 80s for most locations. Still expecting scattered showers and tstms to develop right in advance of the front mainly later this afternoon/evening, as the front slowly drops into/thru the area. Have no worse than 25-30% PoPs in the far NW counties thru 18z, then increased to 30-50% all areas this aftn/eve. SPC has maintained a marginal risk of severe storms across the entire area today, with poor mid-level lapse rates and marginal instability limiting a greater threat.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
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The frontal boundary will sink into NC by 12Z Sat where it becomes nearly-stationary through Sunday. At the same time, low pressure will track eastward along the frontal boundary across TN and into the Carolinas. Have kept a chance of showers (30-50%) across the entire CWA Friday night as the best focus for pcpn will be along/north of the stalled boundary. Saturday is looking overcast as high pressure builds across the Great Lakes/Northeast and nudges south into the Mid-Atlantic, setting up an in-situ wedge pattern. Best chance of pcpn during Saturday morning looks to be along/west of I-95, but spreading eastward to the coast in the afternoon as the aforementioned sfc low approaches from the west. Will have 30-60% PoPs (highest west) before 18z Sat...then increasing 50-70% after 18z. The influence of the sfc low approaching from the west in tandem with an upper trough cutting off over the TN Valley by Sunday afternoon will make for a wet/gloomy end to the weekend. Will have likely to categorical pops 60-90% thru Sunday. There is the potential for heavy rain over much of the region (1 to 2 inches), especially later Sat thru Sun and beyond. Lows Fri night will range from the mid 50 to mid 60s, and range from the upper 40s to upper 50s Sat night. Highs on Sat will range from the lower 60s N to around 70/lower 70s S. Highs on Sun will range from the upper 50s NW to arnd 70 SE.
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&& .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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Latest 21/00z models continue to depict unsettled conditions for at least the first portion of the long term/Sun night through Tue. Deep/anomalous upper low progged to be centered along the southern Appalachians by 00z/Mon, with sfc low along the Carolina coast and weakening sfc high pressure along the southern New England coast. GFS/ECMWF remain in very good agreement with the upper low continuing to dive SE through GA/SC on Mon, while remaining as a closed low. The forecast has trended wetter and cooler for Mon, with the potential for some locally heavy rain all areas Sun night, and mainly over southern and western sections for Mon. All total we could be looking at widespread 2-3" rain amounts from Sat-Mon. Low pressure slowly pulls offshore by Tuesday as high pressure builds in from the NNW with drier conditions returning, but still likely enough moisture for continued 30-40% chance PoPs E and 20% PoPs west. Highs Mon to avg 60-65 F with mid- upper 60s on Tue. Warmer/dry for Wed and likely turning much warmer by Thu as the low finally will be far removed from the region and ridging aloft begins to center off the SE coast. Lows mainly in the 50s with highs mid 70s inland to 65-70 F near the coast Wed, and highs 80-85 F Thu (70s near the coast).
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&& .AVIATION /07Z FRIDAY THROUGH TUESDAY/...
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Other than some locally dense fog around KSBY early this morning, VFR conditions are prominent with mild/SW flow in place. A cold front over the Ohio Valley will move across the mountains today and slowly cross the CWA this afternoon and tonight. Scattered thunderstorms can be expected along and just ahead of the front potentially affecting the TAF sites between 20Z-04z. The front will stall all across NC during the weekend as a well organized low pressure system moves eastward along the front. This will bring widespread rain throughout the weekend with extended periods of degraded aviation conditions. Thunderstorms will also be possible southern portions. The chance of showers continues Monday into Tuesday as low pressure lingers just east of the Carolinas.
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&& .MARINE...
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Latest obs reflect SW flow ~10kt over the marine area this morning. SW Winds will gradually increase later today, as gradient gradually tightens ahead of a cold front which approaches the waters from the NW. Winds to avg 10-15 kt during this period with seas mainly 2-3 ft and waves in the Bay/Rivers 1-2 ft. The front crosses the area this evening into the overnight hours/early Saturday morning, with high pressure building N of the region Saturday. Winds shift to N Saturday post-frontal Saturday morning, with experimental wind probs continue to highlight a brief 2-4 hr window where Low-end SCA conditions will be possible Saturday morning through early afternoon (14-18z) with the initial CAA surge. The best chance of these SCA winds occurring continues to point towards the southern Chesapeake Bay and into the lower James River. Thereafter, increasing model agreement this morning with respect to a more prolonged period of SCA from late Sat night/Sunday morning through midweek...as surface low pressure approaches from the SW Saturday and tracks across the region Sunday into Sunday night. GFS has incrementally adjusted farther south toward the NAM solution with respect to the placement of the quasi-stationary boundary, with the ECMWF remaining a bit north, therefore indicating a brief lull in SCA conditions on Sunday before a second, stronger surge of NNE winds on the back side of the departing system Monday and Tuesday. Given the deepening low pressure and resultant increasing low level winds, expect a period of strong SCA conditions Mon aftn into Tuesday, and the potential for low-end Gales exists, at least over the mouth of the Chesapeake Bay/southern coastal waters during this same late Mon/Tue period. This setup lingers into Tuesday, with winds to gradually diminish Tuesday afternoon and night as the low slowly pushes farther offshore. Seas to build to 6-8 ft and waves to 4-5 ft in the Bay for Mon.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM LONG TERM...LKB AVIATION...JDM MARINE...MAM

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