Area Forecast Discussion
Issued by NWS Wilmington, NC

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692 FXUS62 KILM 230603 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 203 AM EDT Sat Sep 23 2017 .SYNOPSIS... Building high pressure aloft and at the surface will bring dry but warm air across the Carolinas this weekend and well into the upcoming work week. Hurricane Maria is expected to remain well offshore from the forecast area as she passes bye during the upcoming work week. However, she will provide the coastal areas with increasing long period swell that will result in strong rip currents and large surf along the area beaches, as well as hazardous marine conditions especially when venturing thru area inlets to and from the Atlantic Ocean. && .NEAR TERM /THROUGH TODAY/... As of 915 PM Friday...Diurnal cu has basically scoured out with only leftover debris clouds from the earlier isolated showers left. And this too will dissipate. Did not hit the fog as hard tonight when compared to last night. Having been much drier today along with convection isolated. Still moisture avbl below 850mb for Cu to pop back up come Sat mid to late morning. However, as far as the overnight, mainly SKC with thin Ci pushing across the FA later tonight and Sat. This blowoff Ci is from the ongoing convection off the Florida and Georgia coasts unrelated to Hurricane Maria. With winds decoupling across the FA, even along the coast, patchy shallow ground fog will occur. In addition, decent radiational cooling will occur with some sites dropping into the 60-65 range, especially with nights now as long as days this autumnal equinox, and will only get longer as we progress thru the calender to the Winter Solstice. Previous...................................................... As of 300 PM Friday...Since convection is struggling through the window of maximum insolation, diurnal cooling with our lowering ball of fire will put the curtail on convection into the late afternoon to early evening, leaving a clear sky tonight as the cumulus dissolves into the evening sky. Under clear skies and decelerating winds, patches of fog can be expected between 4am and 8am. Minimums will settle to 65-68 across most locals and low 70s near the beaches and ICW. The surfzone and area beaches will begin to possess a hazard as long period SE swell from distant Marie intensifies rip currents, while creating large and powerful breakers near shore. This will pose a threat to surf- waders, and even small children or elderly not in the water but standing by the oceans roar, where wave run-up can be speedy and strong, as wave periods will be on the order of 15 seconds, representing a high translational velocity into the surfzone. It is beyond this period however, namely Sunday, that the surf becomes large. For Saturday 4-7 ft breakers, and a `high- risk` of rip currents along all beaches. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...Although the weather will remain quiet, the seas and surf will not. The main impact this weekend will come from high surf and strong rip currents at the beaches. Otherwise, Jose will continue to churn in the northern Atlantic and Maria will continue its trek northward, while high pressure moves slowly east across the Great Lakes. The Carolinas will basically be under the influence of high pressure in the northeasterly flow between these systems. A weaker gradient flow initially will allow the sea breeze to dominate closer to the coast helping to produce a greater on shore flow Sat eve. The pcp water values will be near 1.3 inches closer to the coast and down near an inch in a drier NE flow Sat eve, but a boundary from Jose will shift south overnight Sat into early Sun. This will produce some clouds and perhaps a spotty shower over the waters. Otherwise expect mainly clear to partly cloudy skies and overnight lows in the mid 60s most places. The winds will pick up on Sun as gradient tightens with northerly movement of Maria which should reach about 500 to 600 miles to the southeast, but coastal Carolinas will remain in dry air and subsidence as ridge builds down over the area aloft and we remain on back side of extreme outer periphery of Maria. H5 heights will be up near 588 dm with 850 temps up near 16 to 17c. This will help to keep a dry forecast with warm temps up in the mid 80s for Sunday. Models show a some drier air advecting in overnight Sunday with slightly lower dewpoints which may shave a couple of degrees off overnight low, but still expected in the mid 60s. && .LONG TERM /MONDAY 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 /06Z SATURDAY THROUGH WEDNESDAY/...
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As of 06Z...Anticipate tempo MVFR conditions at most sites through 12z. Exception will be at LBT and CRE where IFR BR is more likely. LBT has already been flipping between MVFR and IFR conditions and solid IFR with perhaps LIFR will be possible from 9Z through 12-13Z. Once fog mixes out VFR will dominate the remainder of the period with FEW/SCT cumulus around under patches of cirrus from time to time. Seas breeze will result in development of 5-8 kt onshore wind at coastal terminals this afternoon. 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.
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&& .MARINE... NEAR TERM /THROUGH SATURDAY/... As of 930 PM Friday...Small Craft advisory, mainly for significant seas, commences at 6 AM Saturday. A relaxed sfc pressure gradient will result in wind speeds 10 kt or less tonight thru Saturday. The progged sfc pressure pattern will yield a ENE-E wind direction tonight thru Sat. Significant seas will build tonight thru Sat and beyond, reaching SCA thresholds during Saturday. Hurricane Maria`s swell from the SE, will be the primary input to the significant seas thruout the near term and beyond. Periods will range between 13 to as much as 17 seconds. This long period swell, combined with an outgoing tide, will begin to make navigating to and from the Atlantic dangerous and downright hazardous as Maria`s swell builds. Previous................................................... As of 300 PM Friday...Although N through ENE winds this period will not be strong, increasing SE swell from Maria has prompted a `hazardous seas` advisory, effective from 6 AM Saturday through at least early next week, likely into mid-week, since Maria will slow down once offshore of the Carolinas. 4-7 foot SE waves every 15 seconds will produce turbulence and standing waves in area inlets during the outgoing tides, while increasing the width of the surfzone of tumultuous breakers. No TSTMS are expected through Saturday over the 0-20 NM waters. Onshore winds can be expected Saturday with high pressure to the north and Maria east of the Bahamas. SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...High pressure will extend down from the Great Lakes this weekend as Jose continues to spin in the North Atlantic and Maria treks north from north of the Bahamas. A general northeasterly flow will increase heading into Sunday up to 15 to 20 kts in the outer waters, but otherwise winds will be in the 5 to 10 kt range. A very long period swell up to 11 to 15 seconds will continue through the weekend. An increasing northeast shorter period wind swell will combine with this longer period swell to produce an increase in seas from near 6 to 7 ft in outer waters Sat eve up to 10 to 12 ft Sun night into Monday. Expect shoaling and large breaking waves along the length of Frying Pan Shoals. A small craft advisory for hazardous seas mainly due to long period swells will continue through the period. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 300 PM Friday...Long period southeasterly swells will be ongoing Monday, ranging from as high as 8 to 10 feet every 15 seconds in the outer waters (15-20 nm). South of Cape Fear, these are likely to decay to 4 to 6 feet as they approach the coast, but north of Cape Fear, 6 to 8 footers will push in closer. 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...
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SC...High Rip Current Risk from 7 AM EDT this morning through this evening for SCZ054-056. NC...High Rip Current Risk from 7 AM EDT this morning through this evening for NCZ106-108-110. MARINE...Small Craft Advisory for hazardous seas from 6 AM this morning to 6 AM EDT Tuesday for AMZ250-252-254-256.
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&& $$ SYNOPSIS...DCH NEAR TERM...DCH/MJC SHORT TERM...RGZ LONG TERM...CRM AVIATION...III

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