Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 281759 AFDILM Area Forecast Discussion National Weather Service Wilmington NC Issued by National Weather Service CHARLESTON SC 159 PM EDT Fri Apr 28 2017 .SYNOPSIS... Expect high pressure to extend across the area from offshore through Sunday. Expect warm temperatures and isolated sea breeze convection, mainly on Sunday. The next cold front will bring a chance of showers and thunderstorms late Monday into early Tuesday. High pressure will follow for the mid-week period. Low pressure system may impact the region during Thursday with a soaking rain. && .NEAR TERM /THROUGH TONIGHT/...
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No major changes for the early afternoon update. Isolated afternoon convection due to the seabreeze cannot be entirely ruled out so will blend into the previous POPs forecast. Minor near-term adjustments to hourly surface parameters have been made based on observations, but previous forecast appears largely on track. The Bermuda High stretching into the forecast area will promote humid conditions with above average temperatures, especially inland. Expect high temperatures in the mid to upper 80s away from the coast.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
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High pressure and ridging aloft and at the sfc will be the primary drivers affecting sensible weather across the ILM CWA. Closed High with heights of 590+ dam will anchor offshore and east of the Carolinas during this period. The center of the sfc high will basically park underneath the upper high offshore with ridging extending westward and onshore in the vicinity of Cape Romain on Sat, and onshore and inland in the vicinity of Cape Fear Sunday. A semi-tightened sfc pg will occur across the FA thruout this period keeping S to SW winds active, even during the evening and overnight. The sea breeze each aftn and evening will further enhance the S winds. An active low level jet will keep winds busy during the overnight, preventing any widespread fog development, but enough moisture in the low levels may result in low stratus or stratus fractus each early morning. The subsidence from the ridging will keep POPs in check on Saturday but could see isolated sea breeze induced convection during Sunday with the subsidence weakening slightly. Daily high temperatures for Saturday will run in the 80s to lower 90s inland, and for Sunday mainly widespread 80s due to winds having become more southerly thruout enabling some marine influence to extend well inland. Balmy nights can be expected with upper 60s to lower 70s.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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Surface and mid level ridge will weaken and drift east Mon, allowing a cold front to approach from the W. Low pressure and associated strong dynamics and upper level support will be well dislocated from the Carolinas as a cold front moves across the area Mon night. This suggests convection weakening as it moves into the eastern Carolinas. Current timing brings the likelihood for showers and thunderstorms later Mon and Mon night. As the front moves off the coast Tue morning, high pressure along the Gulf Coast will slide east and then offshore to our S during Wed. This should bring a dry period. Deep low pressure will move out of the mid south and Gulf coast states Wed, lifting slowly to the NE. Its associated cold front will move into the Southeast states Thu-Thu night, bringing the risk for robust thunderstorms.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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Diurnal cumulus field will persist across the region this afternoon with only slight chances for precipitation. Probabilities of direct impacts at any of the terminals due to showers/tstorms are too low to mention in the 18Z TAF cycle. Southerly winds will remain gusty near the coast through the evening hours due to seabreeze enhancement. Model guidance suggests that restrictions overnight due to lowering ceilings and/or vsbys are probable, with the most likely outcome being low ceilings due to a nocturnal jet sustaining mixing near the surface. This will aid in preventing widespread surface-based fog and will maintain elevated surface winds through most of the night. Extended outlook...VFR through Sunday with brief MVFR condition possible across the coastal terminals due to spotty sea breeze convection. Periods of IFR/MVFR conditions possible in showers and thunderstorms late Monday into early Tuesday.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS of 330 AM Friday...Southwesterly flow will be king with a large area of high pressure across much of the western Atlantic centered well east of Bermuda. With such a broad swath of flow coming across the Bahamas and into the Southeast a swell component will be able to coexist with the relative small wind waves. For the most part this will yield a forecast of 2 to 4 ft for all zones. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 AM Friday...Sfc high pressure parked offshore from the Carolinas will extend westward and onshore in the vicinity of Cape Romain Saturday, and onshore vicinity of Cape Fear Sunday. Winds Saturday will run S to SW at 10-15 kt, with the SW direction mainly occurring over the waters from Cape Fear northward. For Sunday, the slight deviation with the sfc ridging will produce south winds thruout with speeds 10 to 15 kt initially, increasing to 15 to 20 kt as the sfc pg further tightens as an eastward moving cold front tracks into the western Carolinas late Sunday night. The sea breeze each day will result in winds gusting around 20 kt near shore. Significant seas will run 2 to 4 ft, choppy nearshore each aftn and early evening due to the sea breeze influence. Seas will build Sunday night reaching 3 to 5 ft by daybreak Mon. A SE to SSE pseudo swell at 5 to 7 second periods will be the primary driver for significant seas this period. LONG TERM /MONDAY THROUGH TUESDAY/... As of 300 PM Thursday...Western Atlantic High Pressure will bring increasing S winds ahead of a cold front. South winds 15 to 20 kt early Mon will increase late Mon and Mon night, up to 20 to 25 kt with seas 3 to 5 ft at the start building to 5 to 8 ft. In the wake of the cold frontal passage early Tue, offshore winds will slowly diminish. The offshore trajectories will knock seas down and we should drop below Small Craft Advisory levels by Tue eve. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...

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