Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 231432 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1032 AM EDT Sat Sep 23 2017 .SYNOPSIS... High pressure over the Great Lakes region will maintain warm and dry weather over the Carolinas through the weekend. Hurricane Maria is expected to move northward a couple of hundred miles east of the Carolina coast Monday through Wednesday. Hazardous boating conditions, strong rip currents, and large surf are all expected to develop. A cold front may reach the area Friday, bringing cooler weather for late next week. && .NEAR TERM /THROUGH TONIGHT/... As of 1030 AM Saturday...A Coastal Flood Advisory is now in effect for a few hours in the downtown Wilmington and battleship area for minor impacts associated with high tide early this afternoon. The next high tide is not projected to have as large a tidal range, but thresholds could be met again with tomorrow`s high tide in the early afternoon. Previous discussion...Fog/stratus along the coastal counties will continue to erode with strong insolation today. Low pressure remains off the Jersey shore while a ridge of high pressure from the Great Lakes will dominate the area weather today with a rather dry column expected to be in place through tonight. At H5 heights will continue to slowly increase as some bridging occurs between the ridge NE of Maria and the large subtropical ridge extending the Plains, MS Valley, Great Lakes, and into New England. This pattern will keep the unsettled weather primarily far south/southwest of this part of the Carolinas. No major changes were made to the current forecast. The threat for strong rip currents will continue as swells from Maria impact the surf zone. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 AM Saturday...Closed 500 mb high pressure centered over Pennsylvania on Sunday will bridge across to the Bermuda High on Monday. This "bridging" process is occurring earlier and more strongly than models were thinking several days ago, and this has led to a westward trend in the predicted path of Hurricane Maria as it moves northward. Where over the past several days the storm was expected to follow 70 or 71 degrees longitude as it passed by the Carolina coast, we`re now thinking 73 or perhaps even 74 degrees longitude is more likely. The 500 mb ridge to our north will help sustain a subsidence inversion between 4000-6000 feet AGL Sunday that will lower to 3000-4000 feet on Monday. The stable and dry air aloft will help to keep weather conditions dry across the area both days, although it`s possible a few shallow maritime showers could push onshore into the Cape Fear area by Monday night, particularly if Maria moves as far west as some of the latest models are suggesting. Early morning low stratus is also a good possibility in this pattern. Despite two days of northeast flow 850 mb temps shouldn`t fall appreciably from where we`ve been over the past few days, remaining in the +15C to +17C range. Our forecast highs range from 83-86 near the coast to 86-88 both days. Overnight lows generally 65-70, warmest at the beaches. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 300 PM Friday...Hurricane Maria will be slowly making its way north well off the coast of the Carolinas through the first half of the week. Expected impacts will be dangerous surf and an elevated rip current risk from long period (15 sec) swells. This swell energy will translate into breaking waves as high as 10 to 15 feet along the beaches of New Hanover and Pender counties, and 6 to 10 feet along the beaches of Brunswick, Horry and Georgetown counties into Wednesday. The swell energy should begin to ease late Wednesday, but dangerous surf and an elevated rip current risk will likely continue into Friday. Northeast to north winds will be breezy along the coast, and gust occasionally into the 20-30 mph range by Tuesday- Wednesday. It will be a tough call at this point to determine how much peripheral moisture from Maria will affect the area, however it is reasonable to expect for the ILM CWA, that SE NC will have the best chance for precipitation based on the current forecast track of Maria. The highest PoPs, which will still remain less than 30% at this time, will be Tuesday into Wednesday, before the cyclone gets picked up by the westerlies on Thursday as indicated by both the GFS and ECMWF. Upper level ridging and subsidence west of the hurricane will likely result in a sharp sky cover gradient and temperatures remaining a few degrees above normal through the week. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/... As of 11Z...Fairly widespread low stratus and fog blankets the area this morning, particularly inland from the coast. This moisture is quite thin and should burn off quickly, with VFR conditions developing around 13Z. The remainder of the day should feature excellent aviation weather with mainly clear skies and light northeast winds. Deep vertical mixing should develop some shallow cumulus clouds with bases around 4000 feet by noon, rising to 5000 feet later this afternoon. Clear skies and light winds overnight may develop a little fog again late tonight, but coverage should be much less than we are currently experiencing. Extended Outlook...Mainly VFR conditions through the period with the exception of possible MVFR/IFR conditions due to low clouds and fog each morning, mainly between 08z-12z. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Saturday...A N-NE fetch is in place as high pressure ridges southward across the coastal waters with speeds around 10 knots. Meanwhile, swells from Maria will continue to affect the waters with seas in the 4-6 ft range. Although the dominant wave period is 12-13 seconds the swells combined with the current during times with a falling tide will create steep wave and hazardous wave conditions in/near inlet entrances. Small Craft Advisory will remain in place through the period. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 915 AM Saturday...1021 mb high pressure over the eastern Great Lakes on Sunday will move off the New England coast by Monday. Models have shifted farther west over the 24 hours with Hurricane Maria`s track, now expected to move northward along 73 or 74 degrees west longitude next week. That`s a good 100 miles closer to the North Carolina coast than our thoughts were this time last night, and could bring more of the peripheral winds from Maria`s west side to the area. Gusts as early as Sunday could reach 25 knots, and a Small Craft Advisory has been extended out through Wednesday for increasing northeasterly winds and for very large wave heights, particularly north and east of Cape Fear where combined seas as large as 12 feet could start showing up within 20 miles of the beaches by Sunday evening. LONG TERM /TUESDAY THROUGH WEDNESDAY/... As of 300 PM Friday...Based on the latest forecast track for Maria, northerly winds will peak Tuesday night into Wednesday, with 20 to 25 knots north of Cape Fear. South of Cape Fear, a 15 to 20 knot range can be expected. Expect Small Craft Advisory conditions through the entire period. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...High Rip Current Risk until 8 PM this evening for SCZ054-056. NC...High Rip Current Risk until 8 PM this evening for NCZ106- 108-110. Coastal Flood Advisory until 2 PM EDT this afternoon for NCZ107. MARINE...Small Craft Advisory until 6 PM EDT Wednesday for AMZ250- 252-254-256. && $$ NEAR TERM...SRP SHORT TERM...TRA LONG TERM...CRM AVIATION...TRA is the U.S. government's official web portal to all federal, state and local government web resources and services.