Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 140742 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 342 AM EDT Mon Aug 14 2017 .SYNOPSIS...
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A cold front will meander across the area into midweek, keeping the risk for showers and thunderstorms high. Mid-level ridging will eventually erode the front and bring a return to more typical summertime heat and humidity along with a lower risk for thunderstorms. Another cold front will approach during the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 300 AM Monday...A cold front was running right along the NC/SC border then east toward the tip of Cape Fear this morning. The front was reaching down to Florence and across to Wilmington area early this morning and will drift slowly south through today. A mid to upper trough will run from GA to the east northeast into the Atlantic. Low pressure developing and trying to cutoff at the base of this trough over GA/SC will produce low pressure extending down to the lower levels. This will produce a deep NE to E flow through today and will also bring drier air and subsidence down over NC and into SC by later today into tonight. Initially, this boundary, along with the sea breeze will remain the focal point for convection through today. An area of lower clouds was easing south behind the front while isolated thunderstorms were developing along and just south of the front. Expect lower clouds to break up through the morning and isolated to scattered convective development to be focused along the cold front, sea breeze front and any localized boundaries. Therefore the best chc of thunderstorms will be across SC and along the coast up to Cape Fear while greater amounts of sunshine and drier air can be found over much of NC and N t NW portions of forecast area. The convection and clouds to the south, and NE to E flow behind front will keep temps below 90 most places today. The front will drift far enough south and become increasingly diffuse through later today. Dry air will work its way in especially in the mid to upper levels with clearing skies later today into tonight. Pcp water values will drop down below 1.25 inches by tonight. Guidance shows dewpoint temps dropping to near 70 or just below through late this afternoon into tonight. This will allow overnight lows to fall into the lower 70s across much of the inland areas under mainly clear skies.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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As of 300 AM Monday...A front will meander across the Carolinas during this period. Tropical cyclone Gert will be moving N and then accelerating NE, passing several hundred miles off the North Carolina coast Tue. A mid-level shortwave trough will exert some added lift as it approaches Tue/Tue eve and this coupled with a surface boundary and high moisture content through a deep layer, precipitable water values will be upwards of 2.25 inches, will result in numerous to widespread thunderstorms and showers. The potential for excessive rainfall will be elevated in areas where cells are able to train. Storm motions will be on the order of 15 kt. Upper level support will be in the process of lifting out on Wed which should result in less convective coverage, so perhaps more scattered that day. High temps will be around the 90 degree mark and with high dewpoints, it will feel as if it were 100 to 105 degrees both days. Overnight lows will be in the muggy mid and upper 70s.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 300 PM Sunday...A return to summer heat and humidity occurs late week as the mid-level trough finally gives way to SE ridging. This ridge amplifies in response to a trough digging across the west, and will drive increasing thicknesses, and hence temperatures, into the Carolinas into next weekend. Despite this ridge expanding from the Gulf Coast, heights locally may be relatively lowered thanks to several weak impulses moving to the north in the zonal flow across the Mid-Atlantic. These subtly steeper lapse rates will combine with PWATs still above 2 inches, and strong instability thanks to highs into the 90s to keep the chance for showers and tstms in place each aftn/eve through late week, although with coverage likely less than we have seen much of August so far. By Saturday, a cold front will dig through the OH VLY and then stall in the vicinity causing renewed good chances for convection and slightly cooler temperatures. However, with the ridge overhead this front may entirely dissipate by the end of the period instead of lingering like many of our summer-time fronts so far this season.
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/... As of 06Z...As convection waned overnight, areas of fog developed across the forecast area. Model guidance suggests areas of dense fog and low clouds with IFR ceilings and vsbys. With a frontal boundary running through the forecast area right around the I-95 corridor, the threat for low clouds and fog, possibly dense, will continue through the early morning hours. The fog and low clouds should disperse by mid morning followed by increasing chc of convection as atmosphere becomes more unstable as temps rise. Looks like the convection will once again be focused along sea breeze boundary and front as it shifts south and east before moving north again later today. Extended Outlook...There is a chance for MVFR/IFR ceilings and visibility in showers and thunderstorms Tues through Thurs due to a persistent stalled frontal boundary meandering across the area. Each morning could see MVFR/IFR conditions from low ceilings and reduced vsby from fog. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 300 AM Monday...Light southerly winds will continue to shift around to the NE to E as a cold front drops slowly south through the waters today. The boundary was just reaching the tip of Cape Fear running E to NE through the local waters. Winds will reach up to 10 to 15 kts out of the E-NE behind front. The on shore winds will push seas up from less than 3 ft this morning to near 3 with some 4 fters possible later today into tonight. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 300 AM Monday...A cold front should remain generally upstream through the period as it meanders across the Carolinas. The front may briefly move out across the waters late Tue night or Wed morning. SW winds will dominate, although the wind direction may briefly take on a northerly or easterly component late Tue night or Wed morning. The strongest winds will occur Tue afternoon and eve, up to 15 kt. Seas will be 3 to 4 ft Tue, subsiding to 2 to 3 ft during Wed. Gert will produce an easterly swell of up to 4 ft every 9 to 10 seconds Tue which will begin to decay on Wed. LONG TERM /THURSDAY THROUGH FRIDAY/... As of 300 PM Sunday...Broad high pressure offshore will exert its influence across the waters through late week. This creates SW winds through the period, with speeds only increasing above 10 kt on Friday in response to a cold front approaching from the NW. The prolonged fetch around the offshore high pressure will allow a 1- 2ft/9sec SE swell to persist through the end of the week, but this will become masked by an amplifying 5 sec SW wind wave, especially the latter half of the period. These two primary wave groups will create seas of 2-3 ft Thu, rising to 3-4 ft on Friday.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RGZ SHORT TERM...RJD LONG TERM...JDW AVIATION...RGZ

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