Area Forecast Discussion
Issued by NWS Wilmington, NC

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749 FXUS62 KILM 091723 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1223 PM EST Fri Dec 9 2016 .SYNOPSIS... Cold high pressure will build across the area tonight into the weekend, ushering in the coldest temperatures of the season. A warming trend will follow early next week ahead of the next front. This cold front may stall over or just south of area on Tuesday and may linger across the area producing unsettled weather through mid week. A stronger cold front will move through by Thursday with cold and dry high pressure building in behind it. && .NEAR TERM /THROUGH TONIGHT/... As of 10 AM Friday...No vital changes made to the continuous forecast with a very cool day on tap, it will be a struggle to crack 50, with upper 40s representing maximums for most areas this afternoon. The previous forecaster discussion follows. An airmass with origins in the Arctic will filter into the forecast area through tonight, with the coldest air at 850 mb reaching -4C to -7C by late this evening. Time- height cross sections show a dry column with westerly flow, so expect abundant sunshine today, but unseasonably cool with highs only reaching the mid 40s. A light north-northwest wind should persist through most of the night tonight, although some spots may briefly decouple inland. Low temperatures range is expected to bottom out in the low to mid 20s, with the highest end of that range along the immediate coast. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 AM Friday...850 mb temps will be 2-3C warmer Saturday than Friday, however given the cold start, high temperatures are expected to be similar to Friday, reaching only into the mid 40s. A deep layer of dry, westerly flow should result in another day of mostly sunny skies. Saturday night us shaping up to be a very good radiational cooling setup, so will continue with a minimum temperature forecast leaning toward the low end of the MOS spectrum. Zonal flow will push the surface high pressure off the Mid-Atlantic coast Sunday and the airmass should begin to moderate. There is, as usual, uncertainty with timing the inland progression of the coastal front on Sunday, and although high temperatures are currently forecast to reach into the upper 50s along the coast, temperatures may remain significantly lower than that for much of the day until the coastal trough moves inland. There is also some disagreement between the GFS and ECMWF in terms of precip potential on Sunday, so hopefully these will come into better agreement with 12Z run. But at this time, believe it is warranted to include a low POP across the southern coastal CWA and just offshore, with increasing chances mainly east of the I-95 corridor Sunday night as the trough lifts through. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 330 AM Friday...Southerly flow will increase as gradient tightens ahead of approaching cold front on Monday. This will pump plenty of warm and moister air into the Carolinas. Dewpoint temps will return into the 50s to around 60 with temps reaching up to the mid 60s to around 70. Best chc of pcp will come later on Monday ahead of cold front, though not expecting too much in the way of QPF. The broad, almost zonal flow behind this front may not drive the front too far south on Tues. The GFS is more aggressive pushing it through South Carolina by Tues morning, while the ECMWF shows it bisecting our forecast area from west to east Tues morning as weak low pressure develops along it. This would make the difference of a cool dry day on Tues vs. a potentially cloudy and wetter day for Tues. The GFS does bring this front back north as a warm front by Wed. Overall expect potential for unsettled weather through mid week before a strong cold front sweeps through on Thursday scouring out the clouds and pcp late Thurs into Fri. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 18Z...High confidence in VFR through the valid period. High pressure edging in from the west will become oriented overhead on Saturday. This will continue clear sky conditions, with slowly decreasing winds. Northerly winds will continue to gust through sunset at around 15 kts, but will become light after nightfall. A subtle veering in wind direction is forecast Saturday, but with speeds less than 10 kts and continued SKC. Extended Outlook...Showers possible Mon-Wed. Otherwise VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 10 AM Friday...Strong northerly gradient winds will persist across the waters into this afternoon as high pressure builds offshore. These winds will maintain 5-6 foot seas in the 10-20 nm range into mid afternoon. The Small Craft Advisory will remain in effect today. It is currently set to expire at 6 PM, and but based on latest data, it may be able to be dropped a few hours earlier. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 AM Friday...High pressure center will remain over inland NC, and northerly flow will continue Saturday, although lighter considering the weaker gradient. Direction will become northeast Saturday night and Sunday as a coastal trough develops, and this will introduce the potential for developing showers by Sunday. Sunday night, the trough will lift north, and southerly winds will become southwest by late Sunday night. Seas are expected to build during the night Sunday night, and may reach 4-5 feet towards Monday morning. LONG TERM /MONDAY THROUGH TUESDAY/... As OF 330 AM Friday...Southerly winds will increase ahead of approaching cold front through Monday. This will push seas up from 3 to 5 ft in the morning to 4 to 6 ft, reaching SCA thresholds as gradient tightens ahead of cold front. Winds will veer around to the north by Tues as cold front drops south, diminishing down to 10 to 15 mph with seas subsiding down to 2 to 4 ft. This front may stall across or just south of the waters on Tues and may linger over the waters producing more variable winds and seas through mid week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 6 PM EST this evening for AMZ250- 252-254-256. && $$ SYNOPSIS... NEAR TERM...CRM SHORT TERM...CRM LONG TERM...RGZ AVIATION...JDW MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.