Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 180320 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1020 PM EST Sat Nov 17 2018 .SYNOPSIS... High pressure centered over the NE states will ridge down the East Coast and across the Carolinas tonight thru Sunday. The ridging will weaken once the high shifts offshore from the U.S. A weak disturbance moving across the Atlantic waters may clip coastal areas of NC and SC with isolated showers or intermittent light rain. Cold high pressure over the Plains will push a cold front across the Carolina and off their coasts Tuesday. This high should maintain dry weather through Thanksgiving Day. Skies will slowly cloud up with areas of light rain developing Fri into Sat as a cool wedge sets up. && .NEAR TERM /THROUGH SUNDAY/... As of 10 PM Saturday...High pressure continues to bring clear skies across the area this evening, and will be the main weather feature through Sunday. Main concern tonight will be patchy frost for some areas with strong radiational cooling overnight and minimal chances for patchy fog as relative humidities increase due to cooling with clear skies. Area temperatures will creep up closer to normal Sunday with area highs in the mid to upper 60s. A convergence zone along the coastline may lead to some showers just offshore late Sunday morning to early afternoon, but confidence is low at this point for any measurable precipitation inland of the North Carolina beaches. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 430 PM Saturday...Not much of a longwave pattern change this period. The longwave upper pattern will continue to illustrate a low- amplitude trof affecting basically the entire ILM CWA with ridging along the West Coast up to Alaska and somewhat of a flattened ridge extending north in the vicinity of 55W longitude. Overall, this is somewhat of an expansive low amplitude longwave trof with the mean upper trof line west of the ILM CWA. There are basically 2 upper Jets that will affect the FA this period and basically meet up across the Mid-Atlantic States during this period. This meeting will push a low level s/w trof approaching the FA from the western Atlantic back across the area waters and away from the FA. The Subtropical Jet that tracks underneath the West Coast ridging and pushes eastward with not much deviation north or south. The Polar Jet is progged to continue to dive southeast out of Canada with successive s/w trofs, but does back to an easterly direction and more or less meets up with the SubT Jet either across or offshore from the Mid-Atlantic States. The 1 mid-level s/w trof does interact with a sfc cold front that will be at the doorstep of the ILM CWA by Tue morning with the FA seeing a few showers. Temps this period will likely run 1 to 2 categories above the norm. POPs for -shra will generally be on the low chance side. .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 500 PM Saturday...The longwave upper pattern to continue thru this period as identified in the short term. However, mid- level s/w trofs during this period remain active and possibly a bit more potent. Unfortunately, the best cold air bypasses the ILM CWA to our north. Which fortunately means no winter wx type pcpn to deal with, YET. The influence of the subtropical jet over the polar westerlies continues across the FA, with the sfc CFP Tuesday followed by CAA that brings temps back down to at or slightly below normal as a good chunk of Canadian high pressure breaks away and dives to the Gulf Coast States by Wed and across the FA Thu. A potent s/w trof within the polar westerlies pushes across the NE States early Thu followed by very cold Canadian high pressure that follows a secondary CFP across the FA during the day on Thu. A portion of this cold high is progged to work it`s way across the local CWA due to another wedge setup late Fri into Sat. Will see cloud development and light stratiform liquid pcpn occur by Sat. Flow aloft is not conducive to pull completely onshore the coastal trof that will eventually develop late Fri into Sat. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... As of 00Z... VFR through the overnight hours despite a few Ci passing by this evening. Calm winds and good radiational cooling will allow for the possibility of some patchy fog inland which may bring some limited aviation impacts. Do not expect more than light BR and MVFR at FLO/LBT. With the Ci passing to the south, would expect LBT may have the best chance to reach MVFR. Throughout the day, should see clear skies with a few mid-level clouds possible in the northern part of the area as a weak trough moves toward the coast mid-morning. Toward the end of the forecast period, a small disturbance moving to the east will bring mid-level clouds. Extended Outlook...Flight restrictions possible overnight Sunday into Monday due to a weak disturbance off the coast. Otherwise, VFR. && .MARINE... NEAR TERM /THROUGH SUNDAY/... As of 1000 PM Saturday...High pressure, north of local area, will migrate slowly eastward reaching the NJ coast by Sun afternoon. As the high continues to wedge southward into the Carolinas, the winds will veer only slightly, maintaining a northeast flow. Winds right along the coast will become more on shore, but overall winds will remain very light, 10 kts or less. Seas will remain 2 to 3 ft most waters. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 430 PM Saturday...No SCA or SCEC this period. Sfc ridging will extend across the area waters from high pressure centered over New England initially that will be exiting off into the Atlantic by daybreak Mon. The sfc pg will already be in a relaxing phase with NE to E directions around 10 kt speeds. A rather chaotic pressure field encompasses the area waters Mon night ahead of an approaching cold front. An approaching mid- level s/w trof will help sharpen the sfc pg ahead and behind the cold front that will be on the doorsteps of the FA come sunrise Tue. Sig seas will run 2 to 4 ft thruout this period with a dominating 9+ second period Easterly ground swell. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 500 PM Saturday...Looking at CFP during Tue under gusty NW to N winds. This will be followed by a secondary CFP during Thu which could see SCEC or SCA conditions set up especially from Cape Fear northward. Eventually, the entire CWA waters from Surf City to South Santee River will be under a SCA after the secondary CFP. With N to NE winds at 15 to 25 kt as the sfc pg tightens in response the wedge setting up. Significant seas will run 3 to 6 ft by the end of the long term period. This slow building process is due to a shortened fetch. However, with winds progged to further veer to the NE or ENE by the end of this fcst, sig. seas will likely further build. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RGZ NEAR TERM...MCK SHORT TERM...DCH LONG TERM...DCH AVIATION...21 MARINE...ILM

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