Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 251004 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 604 AM EDT Thu May 25 2017 .SYNOPSIS... A cold front will move offshore this morning. High pressure will then build in from late today 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 /THROUGH TONIGHT/... As of 3 AM Thursday...Deep 5h trough over the eastern CONUS today will lift northeast overnight. Shortwave rotating around the base of the 5h trough will push a cold front, currently just west of the area, off the coast by mid to late morning. Not expecting much from the broken line of showers moving across the forecst area out ahead of the front. Surface layer remains stable and even a storm of some significance would have trouble getting any strong winds or rotation to the surface. Line has had very little in the way of lightning with it and do not anticipate that this will change. Deep dry air, very evident on water vapor imagery, is poised to start moving into the forecast area and this will bring an end to any shower activity until later today. Stacked low remains over the OH Valley today as the 5h trough axis shifts overhead this afternoon before lifting northeast tonight. Trough axis arrives overhead during peak heating, just as a shortwave accompanied by mid level moisture moves around it`s base. Daytime heating combined with mid level cooling and steepening mid level lapse rates is usually a recipe for isolated to scattered afternoon showers and thunderstorms. Although temps today will be near climo, the anomalously cold nature of the 5h trough will increase mid level lapse rates into the 7-8C/km range for the afternoon. Although the MOS guidance is showing a very low pop for this afternoon, past experience has shown that just about any shortwave/5h trough with smallest bit of moisture has the ability to generate convection. Will remain on the wet side of guidance and carry chc pop across the area this afternoon and evening. Cold pools aloft frequently generate small hail and can always lead to a few storms with larger hail and/or damaging winds, but it appears the best chance for severe weather will be just north of the area. Any activity that does develop will end around sunset with the loss of heating and post shortwave/trough subsidence bringing a rapid end to any lingering storms. Cold advection behind the front is delayed but by evening cooler and drier air will be spreading over the region. Skies clear out and despite winds close to 10 mph for much of the night lows will drop below climo. Away from the coast lows in the mid to upper 50s are likely. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 3 AM Thursday...Weak high pressure centered over Florida will extend north across the forecast area Friday, then will be suppressed to the south as a slow moving cold front drifts south towards the region. A dry column and lack of forcing will make for a rain-free start to the Memorial Day weekend, at least up until Saturday night. For overnight Saturday have introduced slight chance for showers and thunderstorms with the front lingering to our north. Confidence not high that we will see precip in that time-frame though, as guidance not in good accord with frontal placement. Temperatures will gradually warm through the period, with highs in the mid 80s for Friday and right around 90 for Friday. && .LONG TERM /SUNDAY 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 /12Z THURSDAY THROUGH MONDAY/...
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As of 12Z Thursday...Good confidence VFR through the TAF valid period for all terminals. Forecast uncertainty revolves around possible convection this afternoon as an upper disturbance passes overhead. Have added VCTS all sites for a few hours this afternoon to signal this possibility. SW winds this afternoon will be breezy/gusty, with gusts up around 25 mph or more. Extended Outlook...Localized MVFR conditions are possible in scattered showers and thunderstorms Sunday and Monday afternoons and evenings.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 3 AM Thursday...Winds and seas warrant continuation of small craft advisory through today and into tonight. Strong southerly flow will veer to southwest this morning before ultimately ending up westerly late in the period. Gradient will start to relax late in the day which will result in speeds decreasing. Seas will follow a similar trend, running 5 to 8 ft into late morning then gradually trending downward, eventually dropping below 6 ft late tonight. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 3 AM Thursday...Expect generally W to SW winds through the short term as high pressure builds in from the west. Seas of 3 to 5 ft Friday morning for our NC waters will subside as the gradient relaxes, possibly ramping up again Saturday night as a weak front inches down from the north. Seas for our SC waters will be a bit more moderate and should not exceed the 2 to 4 ft range through the short term. LONG TERM /SUNDAY 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...
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SC...Beach Hazards Statement through this evening for SCZ054-056. NC...Beach Hazards Statement through this evening for NCZ106-108- 110. MARINE...Small Craft Advisory until 6 AM EDT Friday for AMZ250-252-254- 256.
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&& $$ SYNOPSIS...REK NEAR TERM...III SHORT TERM...REK LONG TERM...RGZ AVIATION...REK MARINE...REK/III/RGZ

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