Area Forecast Discussion
Issued by NWS Wilmington, NC

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731 FXUS62 KILM 080929 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 429 AM EST Thu Dec 8 2016 .SYNOPSIS... High pressure will bring a dry and seasonable day today. A cold front will move through later on Thursday, ushering in the coldest temperatures of the season for the first part of the weekend. A warming trend will follow Sunday into Monday ahead of the next cold front. Expect seasonable and dry weather Tuesday as high pressure builds in behind front. Another frontal system will affect the area during the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 330 AM Thursday...Areas of stratus early this morning has prevented fog from becoming an issue. However, A few pockets of clear skies earlier across Horry County allowed fog to develop across the Myrtles. If the clear skies prevailed a bit longer, the fog would have likely reached dense thresholds. For now, will keep the fog low key. During daytime morning, will see the sfc based inversion break allowing mixing to occur resulting in drier air able to break down the low stratus. Will see insolation later this morning, however clouds ahead of the approaching cold front will fill back in as it approaches the FA from the northwest. Only minimal convergence along the front which is likely not enough for pcpn development. In fact, with westerly flow aloft, moisture accompanying this front will scour-some as it progresses to and across the FA this aftn. Looking at mid-late aftn when the cold front clears the ILM CWA Coast. The sfc pg will tighten after the CFP resulting in NW winds increasing. the cold surge lags slightly behind the front and will really begin to be realized during the pre-dawn Fri hours. Post frontal clouds will affect the FA overnight, with the drier air thru the atm column occurring during Friday, after the mid-level trof axis pushes thru. Used the hier max temps from the avbl model mos guidance and also stayed on the hier side for tonights mins which will occur around or after daybreak due to CAA infiltrating the FA. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Overwhelming headline for the THU/FRI period is `Old Man Winter Dips His Toes into the Carolinas`, as the leading edge of a bubble of Arctic born air infiltrates late on Thursday. Widespread sub-freezing 20s will greet SE NC and NE SC daybreak Saturday as this high settles nearly overhead. Even with cold air advection breezes Thursday night, temps well inland may fall below freezing. A brief deepening of column moisture Thursday into the afternoon could provoke or motivate a few showers to form just ahead or along the cold front late THU with support from low-level convergence and diffluence aloft. Dewpoints and moisture remain limited and no thunder or appreciable rainfall is anticipated. Since the front arrives later in the day, and a downsloping W wind will precede this surface boundary, look for mild temperatures well in the 60s Thursday, before the northern door swings open wide and brings a talked-about chill to the area. Wind chill values will bottom out very early Saturday in the upper teens to lower 20s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 3 AM Thursday...Boundary and surface temperatures progged to recover some 10-12 degrees F on Sunday as the wedge weakens beneath strong low level warm advection. Increased cloud cover resulting from the upglide will temper the warmth slightly but Monday will benefit from a much warmer start and should actually turn out warmer than climatology. Rain chances associated with coastal trough Sunday into Sunday night will continued to be carried but capped low as they are likely a case of over aggressive moistening by guidance, a seemingly common error. Rain chances should max out Monday as a cold front moves through, though the lack of deep layer veering should keep QPF prospects minimized as it prevents the mid levels from moistening. After a dry and fairly seasonable Tuesday we may be looking at another Arctic cold front on Wednesday. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... As of 06z...A weak frontal wave is approaching from the northwest. Ahead of this system a fairly solid deck of MVFR ceilings have developed. This moisture was very poorly initialized by model guidance, lowering the forecast confidence regarding its tenacity. Normally the best course is to keep lowered conditions as-is until daybreak especially this time of year. There is some wind above the surface layer so any VSBY restrictions likely fairly transient and only MVFR. VFR after sunrise with just a windshift to the NNW spreading south across the terminals this evening as the Arctic front pushes through. Extended Outlook...VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 330 AM Thursday...SCA raised for this evening through late Friday afternoon. Benign conditions this morning will give way to an increase in wsw-w winds around 10 kt ahead of the approaching cold front. Look for the CFP during late this aftn, to well offshore during this evening. The sfc pg tightens quickly after the CFP with NW winds increasing to 10 to 20 kt by sunset. The cold surge will lag behind the cold front but should be in full force across the area waters during the pre-dawn Fri hrs. Winds will further increase to 15 to 25 kt with added gustiness to 30 kt, especially across the warmer outer waters and closer to the Gulf Stream or any eddies having broken off from the Stream. Significant seas will run 1 to 2 ft this morning, building to 2 to 4 ft late this afternoon. Further building to 3 to 5 ft, up to 6 ft 20 nm out of the Capes late. Weak Pseudo swell from the south at 7 second periods will dominate this morning, then give way to building wind driven waves at 3 to 5 second periods tonight. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 PM Wednesday...Deteriorating marine conditions the main headline this period as a powerful blast of cold air late on Thursday through Friday brings gusty N winds of 20-25 KT and choppy steep waves. Gusts to 30 KT will be common across the outer and slightly milder offshore waters. A Small Craft Advisory will be needed for this Arctic High in wake of a cold frontal passage late in the day Thursday. Offshore navigation is discouraged for small craft Thursday night and Friday, and with the season comes the potential for hypothermia in the event of an overboard situation. The Advisory will be likely be issued overnight, but will allow another model run as to glean more accurate timing of the event. LONG TERM /SUNDAY THROUGH MONDAY/... As OF 3 AM Thursday...Winds initially out of the SE on Sunday with a weak coastal trough in place. Late in the day into Sunday night this feature washes out and a SSW flow gets established and strengthens some. A few 5 ft seas may materialize well away from shore but the coast-parallel fetch may preclude headlines since most of the area sees smaller waves. Monday`s forecast rather uncertain as models are in poor agreement in timing the next front. The slower and slightly favored solutions would allow for a moderately strong prefrontal SW flow that would likely require an advisory. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 9 PM this evening to 6 PM EST Friday for AMZ250-252-254-256. && $$ SYNOPSIS...MBB NEAR TERM...DCH SHORT TERM...DCH LONG TERM...MBB AVIATION...MBB

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