Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 181041 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 642 AM EDT Sun Mar 18 2018 .SYNOPSIS... A southward moving cold front, with isolated showers ahead of it, will move across and south of the forecast area by midday. Lingering clouds and weak high pressure with slightly cooler temperatures, will be on tap this afternoon through early Monday. A warm frontal passage will occur late Monday, prior to it, there will be a chance for light rain. This will transition to convective type precipitation as the atmosphere becomes increasingly unstable late Monday night thru Tuesday night. Much colder air will infiltrate the forecast area Wednesday thru Friday, and if enough moisture is available, wintry precipitation may mix with ongoing light rain Wednesday night, with all precipitation ending early Thursday. High pressure accompanied by a much drier and colder air mass, will settle in Thursday thru Friday. The next chance for rainfall will come from a low pressure system that will push across the area next weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 3 AM Sunday...a short-wave trough seen in the GOES-East water vapor imagery is in Virginia and northwestern North Carolina. This short-wave trough will shift to the Atlantic coastline north of the forecast area. The impact of this wave has been the convection that developed to our north along the frontal boundary and will move into the northern part of the forecast area before sunrise. This wave will force the frontal boundary back south today. The models are depicting the front to shift into to Georgia on Sunday. A developing surface low pressure area over the southern plains will cause the surface front well to our south to begin shifting northward with isentropic lift of the 295K surface seen to begin late Sunday. The condensation pressure deficit does not indicate saturation of the layer until after 12 UTC Monday. So for precipiation expectations, a dry Sunday is expected with low stratus on the north side of the front dissipating by mid-morning. The increase of cloud cover will begin late Sunday with a slight chance of showers after midnight mainly over northeast South Carolina. Maximum temperatures will be cooler on Sunday with the frontal passage. Temperatures will range from the lower 60s in the northern portions of southeast North Carolina to the lower 70s in Williamsburg and Georgetown counties. Lows Sunday night will range from the lower 40s in the north to around 50 in the southern sections of northeast South Carolina. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 400 AM Sunday...Basically looking at unsettled wx conditions thruout much of this period. A whopping 1015mb high affecting the area early Monday, will give way to an approaching low pressure system from the west. At the same time, a warm front will lift northward, finally crossing the FA late Mon night. The low will have hooked up with the warm front Mon night and both will cross the FA together. This will enhance the precipitation and as a result, have increased the QPF across the board specifically Mon thru Mon night. A somewhat of a dry punch will push across the Carolinas during Tue and if enough insolation also becomes available, temperatures should easily break into the 70s across most locations. Then it`s back to reality, with a cold front progged to drop south across the FA Tue evening. In it`s wake, much colder air will slowly infiltrate the FA with Wed lows in the upper 30s to mid 40s...this compared to the previous 2 nights with lows in the 50s and 60s. Models are in some disagreement with how much cold air makes it to the FA as a weak to modest negatively tilted mid-level s/w trof drops southeastward. It`s path with respect to the ILM CWA will be crucial for the possibility of wintry pcpn that may occur immediately after this period Wed into Wed night along with 32 degree temps. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 344 PM Saturday...Low pressure pulling off the coast will bring a lull Tuesday, before another low develops and brings periods of showers Tuesday night through Wednesday, changing over to snow or a rain/snow mix Wednesday evening. Forecast low temperatures and thermal profiles, depict a brief period of frozen precipitation is possible across much of the area. Sharp mid- level drying will end PCPN prior to daybreak Thursday. Significant accumulations are not expected due to warmer ground, but a "Frost` advisory, or `Freeze Warning` may be needed very early Thursday, favored over interior SE NC, but could reach into parts of NE SC. Did not include thunder this period because of stable/cooler low levels, but elevated instability will exist to some degree. QPF Tue- Wed night averages to 3/10" to 5/10". && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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As of 12 UTC...A frontal boundary is sagging southward through the CWA. Behind the front, ceilings are lowering. It is unclear whether they will lower to IFR or not. There are pockets of IFR at this time, but will stick with mostly MVFR at this time. Later today, skies will scatter with VFR conditions from this afternoon through the end of the forecast period. Light winds tonight. Extended outlook...Periods of MVFR Sunday through Wednesday. Chances for convection increasing Monday through Thursday.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 3 AM Sunday...currently southwest winds of 15 to 20 knots are occurring at Frying Pan Shoals buoy with seas of 4.5 feet. Closer to the coast seas are running 2.5 feet 10 miles southeast of Wrightsville beach where winds are southwest at 10 knots. The frontal boundary which has been waffling north to south and south to north the last few days will again shift southward through the entire forecast area by today. The wind direction will change quicly from the southwest to the northwest later today. Overnight the winds will continue veering to the east and southeast by late Sunday night. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 400 AM Sunday...Monday looks like it could partially be a washout, meaning light rain initially will become more showery with possible thunder late Mon thru early Tue. A warm front will lift across the local waters by early Tue with East to southeast winds ahead of a warm front will veer to the SW after it`s passage early Tue. The sfc pg will tighten late Mon night and during Tue as a sub-1000mb area of low pressure having hooked up with the warm front, pushes off the VA Capes or NE NC by Tue morning. The lows accompanying cold front will drop southward and clear the local waters by midday Tue. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 344 PM Saturday...This is shaping up to be a difficult marine period, as a series of strong low pressure systems impact the coast. Gusty SW winds 20-25 KT Tuesday and Tuesday night, will shift to north equally strong, if not stronger Wednesday as N and NW winds kick up in a cold air surge. Gusts to near Gale force are not out of the question Wednesday over the outer waters, with current numerical wave guidance at FPSN7 assigning 7 feet Wednesday. Very cold temperatures will greet mariners early Thursday, in a moderate, but biting, offshore wind. The tightened sfc pg from late Mon will actually further tighten Tue into Tue night given the strength of the sfc low. Combined with CAA after the CFP, winds should reach SCEC and SCA thresholds. There is a Gale possibility but that will depend on any further strengthening of the sfc low and also its placement and movement. Nevertheless, not a favorable 2 days to spend on the open Atlantic waters. Significant seas will see their lull during Mon at 1 to 3 ft. WAA and veering winds will result in seas building to 3 to 5 ft during Tue. And after the CFP, NW to N wind directions will limit the fetch for which wind waves to build from. Nevertheless, will see 4 to 7 ft seas come Tue night into Wed. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DRH SHORT TERM...DCH LONG TERM...MJC AVIATION...43 is the U.S. government's official web portal to all federal, state and local government web resources and services.