Area Forecast Discussion
Issued by NWS Wilmington, NC

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554 FXUS62 KILM 250015 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 815 PM EDT Wed May 24 2017 .SYNOPSIS... Additional showers and thunderstorms will precede the passage of a cold front on Thursday. High pressure will build in late Thursday into Friday and persist into the weekend, bringing dry weather and increasing heat. A cold front will reach into the Carolinas early next week finally moving off shore by mid week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 800 PM Wednesday...The eastern Carolinas are in the warm sector of 993 mb low pressure centered near Cincinnati, Ohio. The cold front extending south from this low has reached the mountains of western NC and extends down through Georgia. This front should sweep east and through the eastern Carolinas late tonight. Tornado Watch #266 has been cancelled for the counties in our forecast area. Instability never recovered behind the mid- afternoon area of thunderstorms, and despite strong low-level wind shear and reasonably good 0-1 km helicity the lack of surface-based instability should preclude a severe weather threat overnight. I have maintained a 60 percent chance of showers in the forecast mainly through midnight, with precipitation chances diving rapidly after midnight as drier air begins to move in from the west. No reports of severe weather have been received from the pair of tornado-warned storms we had in Darlington and Bladen counties this afternoon. In both cells it`s possible marginal low-level lapse rates kept the circulation aloft from descending down to ground level. Given a healthy radar presentation, it might be an interesting local study to see how well correlated steep low level lapse rates are with verified tornado touchdowns... && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Deep low pressure system will continue to lift rapidly off to the northeast Thurs night. Plenty of dry air will advect in with westerly winds on the back end. Pcp water values around an inch Thurs eve will drop below .75 inches through early Fri with sfc dewpoint temps down into the mid 50s. Overall expect clearing skies Thurs night with temps dropping down closer to 60 for overnight lows and plenty of sunshine on Friday bringing temps back up into the mid 80s most places. Surface winds will back to the SW Fri evening allowing for some moisture return bringing dewpoint temps up to around 60 or so. This will keep overnight lows Fri night several degrees warmer than previous night, down into the mid 60s most places. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...Ridge will build up from the Gulf Coast on Saturday as surface high shifts east and off the Florida coast. This will maintain a warm and increasing moist flow with rising heights in the mid levels. The 850 temps will be up to 16 to 18c on Saturday. Overall expect plenty of sunshine and well above normal temps on Saturday, reaching around 90 most places. A minor perturbation riding over the ridge overnight Saturday should produce some clouds and maybe a spotty shower but will move off the coast by early Sunday. Expect high pressure to hold with plenty of dry air and subsidence in the mid levels to maintain a cap on convection through early Sunday. The ECMWF is more bullish with a digging northern stream shortwave pushing a cold front south and east toward the Carolinas on Sunday and suppressing ridge farther south. This could lead to greater potential for clouds and showers and slightly less warm temps, but for now will lean more toward the GFS and keep a more optimistic forecast for sunnier and warmer weather on Sunday. If GFS forecast holds, mid level heights will continue to rise through the weekend as ridge builds up from the south and temps will rise up around 90 again on Sunday.Overall confidence is lower through early next week as a slow moving cold front reaches into the Carolinas and finally moves off the coast on Tuesday or possibly not until Wed. Therefore should see increasing chc of showers Sun aftn through Mon. Temps will continue to rise well into the 80s Mon through Wed. A moist summertime like air mass will keep overnight lows && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 00Z Wednesday...Breezy southwest winds along the coast could gust over 25 knots now through about 06Z. One or two more bands of showers are anticipated tonight before drier air builds in from the west late. Showers with embedded thunderstorms currently extending south of Augusta, GA should reach FLO around 01Z; MYR, CRE and LBT around 02Z, and ILM around 03Z. Near these showers ceilings should fall to around 1500 feet (MVFR) with visibilities 4-5 miles. After 1-2 hours these showers should exit off to the northeast and attention will then shift to what should be a weakening line of showers along the actual surface cold front advancing eastward from Georgia. Once this feature makes it to the coast around 06-07Z, VFR conditions are expected to develop and last through Thursday. With gusty southwest winds expected Thursday, only isolated showers are expected during the afternoon hours. Extended Outlook...Localized MVFR conditions are possible in scattered showers and thunderstorms Sunday and Monday afternoons and evenings. && .MARINE... NEAR TERM /THROUGH THURSDAY/... As of 800 PM Wednesday...Strong low pressure located over the Ohio Valley will push a cold front eastward from Georgia across the Carolina coastal waters late tonight. Before the front gets here, a period of strong southerly winds is expected overnight with gusts probably reaching 30 knots at times. Showers and isolated thunderstorms are expected to redevelop this evening and last through about 3 AM before drier air arrives from the west and reduces the potential of rain. Wind directions should veer more southwesterly late as the front crosses. Seas of 5-6 feet should increase to as large as 8 feet out toward 20 miles from shore overnight as the stronger winds churn the sea surface up. A Small Craft Advisory remains in effect. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Marine conditions will improve Thurs night into Fri in a diminishing off shore westerly flow. The offshore flow will keep highest seas farther off the coast. Initially SW-W flow between 20 and 30 kts will maintain seas of 4 to 8 ft but by Fri morning seas will drop down to 3 to 5 ft in westerly winds 15 to 20 kts. Therefore the Small Craft Advisory in effect will expire Fri morning. Winds and seas will continue to diminish with westerly winds dropping down to 10 kts or less by Fri evening. Winds will back slightly Fri night becoming more SW around high pressure to the south, remaining around 10 kts or less. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Wednesday...High pressure to the south will maintain a SW return flow 10 to 15 mph through much of the period. Seas between 2 and 4 ft will rise up to 3 to 5 ft on Sunday with increasing winds up to 15 to 20 kts as a cold front makes its way toward the Carolinas. Tightened gradient flow between slow moving cold front to the west and high pressure to the south and east may push winds up to 15 to 20 kts through early next week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Beach Hazards Statement through Thursday evening for SCZ054- 056. NC...Beach Hazards Statement through Thursday evening for NCZ106- 108. MARINE...Small Craft Advisory until 6 AM EDT Friday for AMZ250-252-254- 256. && $$ SYNOPSIS...RJD NEAR TERM...TRA SHORT TERM...REK LONG TERM...RGZ AVIATION...TRA

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