Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 280159 CCA AFDILM Area Forecast Discussion...Corrected National Weather Service Wilmington NC 958 PM EDT Thu Apr 27 2017 .SYNOPSIS... High pressure offshore will bring a warming and drying trend late this week through the weekend. A weakening cold front will bring a few showers or a thunderstorm tonight inland and early Friday at the coast. A stronger frontal system will bring a chance of rain late Monday and early Tuesday. Another storm system may impact the region with a soaking rain next Thursday. && .NEAR TERM /THROUGH FRIDAY/... As of 1000 PM Thursday...Low stratus is developing along the South Carolina coast a few hours faster than anticipated. Have increased sky cover forecasts and adjusted hourly temperature curves appropriately as this is interfering with radiational cooling. The line of showers across central and western South Carolina is slower to move east than anticipated. Latest HRRR runs show only spotty coverage as it enters the Pee Dee region after midnight, but still shows a resurgence as it approaches Cape Fear just before daybreak Friday. The HRRR is developing surface-based CAPE near 3000 J/kg late tonight along the coast-- something I was going to immediately dismiss until I started adjusting NAM soundings using the observed temp/dewpoint at Frying Pan Shoals buoy (75/73) and easily got 2600 J/kg. Hmmmm... PoPs have been bumped up to 30 percent in the Myrtle Beach/Cape Fear region after 3 AM. Discussion from 730 PM follows... Isolated showers and maybe even a thunderstorm will develop overnight as a dying cold front approaches from the west. The meager surface-based instability is becoming capped off due to the cooling boundary layer, however elevated instability based around 5000-7000 feet AGL will continue overnight. PoPs range from 10-30 percent, lowest near Georgetown and highest west of I-95. The last several HRRR runs and some of the recent RUC model runs also suggest late- night showers could develop near the Brunswick County coast, although I am not certain what mechanism is in play. No significant changes have been made to forecast low temperatures, expected to range from the mid 60s near and west of I-95 to the lower 70s on the beaches. This is exceptionally warm for late April, about 15 degrees above normal. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Bermuda High will take hold of the area with ridging all the way up through the mid and upper levels. This will maintain a deep southerly return flow with very mild summer-like weather. Plenty of dry air and subsidence through the mid levels will maintain a cap on convection although shallow low level moisture will be quite rich. Overnight winds should prevent fog, but sounding data shows potential for a few hours of saturated column up to 1500 ft or so and greater potential Sat night into Sun morning. Therefore may see some stratus around overnight but will dissipate as sun rises Sat morning. Should also see some cu develop right along sea breeze boundary as it pushes inland Sat aftn. Temps will run about 10 to 15 degrees above normal with plenty of sunshine on Sat. Both Fri night and Sat night lows will near or around 70 degrees with daytime highs soaring through the 80s to around 90 in many spots inland. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...Western Atlantic High Pressure will maintain deep southerly flow on Sun. Although a shower along the seabreeze can`t be ruled out, subsidence on the periphery of the ridge should keep afternoon convection to a minimum, except along the inflection point, will keep POPs out of the forecast at this time. 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. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... As of 00Z Friday...Isolated convective showers associated with a dying cold front may move into eastern North and South Carolina later this evening. Odds of precipitation occurring at any of the airports are 20 percent or less, and flight category restrictions are unlikely. Perhaps of greater concern is the potential that low stratus will develop late this evening as very moist air gathering just offshore moves inland. Ceilings as low as 600-800 feet are possible, with IFR restrictions forecast in the TAFs for ILM, MYR, and CRE beginning around 05Z. It is worth noting the NAM model has much greater potential for low ceilings than the GFS or RUC models. Any low ceilings will either burn off just after sunrise, or push back offshore as wind directions veer more southwesterly late tonight. VFR conditions are expected for all areas after 13-14Z Friday. Extended outlook...VFR through Sunday. Periods of IFR/MVFR conditions are possible in thunderstorms late Monday into early Tuesday. && .MARINE... NEAR TERM /THROUGH FRIDAY/... As of 730 PM Thursday...The afternoon seabreeze is beginning to wind down as temperature contrasts across the beaches relax. Wind gusts as high as 27 knots occurred at Wrightsville Beach, 24 knots at Topsail Beach, and 21 knots reported at the Georgetown, SC airport. South-southwesterly winds 10-15 knots are expected for the remainder of the night. Seas consist of choppy 4-5 second wind waves overlaid with a 9 second southeast swell, totaling 3-4 feet, and little change is anticipated overnight. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Southerly return flow will persist around the periphery of the Bermuda High which will keep a stronghold on the local waters through the period. Winds will run 10 to 15 kt with gusts to 20 to 25 kt possible especially the nearshore waters during the afternoon sea breeze. Seas will run 2 to 4 ft, but may see some 5 fters in outer waters. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...Western Atlantic High Pressure will bring increasing S winds ahead of a cold front. S winds Sun and Sun night will be increasing to 15 to 20 kt. Seas will increase to 4 to 6 ft by early Mon morning. S to SW wind speeds will increase further Mon and Mon night, up to 20 to 25 kt as seas build to 5 to 8 ft. Then in the wake of the front Tue, developing offshore winds will trend lower. 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...Coastal Flood Advisory until 1 AM EDT Friday for NCZ107. MARINE...None. && $$ SYNOPSIS... NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RJD AVIATION...TRA MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.