Area Forecast Discussion
Issued by NWS Wilmington, NC

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027 FXUS62 KILM 242325 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 725 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 600 PM Wednesday...Behind this afternoon`s wave of thunderstorms surface temps have cooled into the 70-73 degree range and instability has really diminished compared to earlier this afternoon. This has led to a recent reduction in the coverage and intensity of convection from SE North Carolina all the way down into the Florida Panhandle. While there is still sufficient elevated instability to sustain another wave of showers and embedded thunderstorms later this evening, I do not anticipate we`ll be dealing with severe weather or widespread heavy rainfall from this point forward. Forecast PoPs remain quite high (60-90 percent) from 8 PM through about 11 PM as the band of convection across east-central Georgia moves our way, then ramps down rapidly overnight. I have cancelled the Flash Flood Watch given the lack of heavy rainfall expected tonight. I initially planned to remove our counties from the tornado watch, however was asked to leave them in a while longer by the Storm Prediction Center. Discussion from 300 PM follows... There is a risk for severe thunderstorms into this eve. The pre- storm environment indicates LCLs near 700 ft this afternoon and eve. Also, low level jetting increases up to near 50 kt. Deep moisture and associated thunderstorms will be working north into this environment and will have the potential to produce strong to damaging wind gusts. The low LCLs along with modest shear will make isolated tornadoes possible. Although storms will be moving quickly, they will have the tendency to train and thus, the Flash Flood Watch will remain in place, although the risk for flash flooding has decreased with the lack of significant rainfall over the last 18 hours or so. Urbanized areas will be the most susceptible to flooding this eve. Large hail is also possible with the deepest convection. A dry slot wrapping around 500 mb trough will work into the area overnight, ending the risk for showers and thunderstorms from W to E as the mid levels dry out and forcing exits to the NE. The 500 mb trough axis continues to be slow moving and it is the strong shortwave rounding the base of the trough that ultimately pushes the cold front into and through the forecast area on Thu. This shortwave may set off a few showers or even a thunderstorm or two on Thu as cooling begins aloft and heating intensifies at the surface. At this time, it looks like the risk for thunderstorms with hail will be largely to our N, but will include some risk for showers and thunderstorms, mainly late morning and afternoon with the highest POPs for our northern zones. && .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 300 PM Wednesday...A Small Craft Advisory remains in effect through the period. SW winds will be sustained at up to 25 to 30 kt. A few gusts up to gale force will be possible tonight. Seas will be in the 6 to 9 ft range, peaking tonight. Widespread showers and thunderstorms will produce poor visibility into the first part of the overnight. Some storms may be severe. Showers and a few thunderstorms on Thu will be isolated to possibly scattered. 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...RJD/TRA SHORT TERM...REK LONG TERM...RGZ AVIATION...TRA MARINE...

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