Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 171039 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 540 AM EST Wed Jan 17 2018 .SYNOPSIS... A cold front will cross the coast today, bringing a mix of rain and snow, with accumulations up to 2 to 3 inches inland. Cold and dry arctic air will follow late today into Thursday. Temperatures will warm into the weekend, as high pressure moves offshore. Another cold front will bring rain chances early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Wednesday...A Winter Storm Warning has been issued for Marlboro and Robeson counties. A Winter Weather Advisory remains in effect for inland portions of forecast area. Greatest amounts will between 2 to 3 inches along northern portions of Marlboro and Robeson counties. A potent mid to upper trough will push cold front south and east through today. A weak coastal trough/low well off shore will maintain a light northerly flow along the coast while winds inland will be more variable. Expect more of a northerly flow over NC as front makes its way across but more of a westerly flow over SC. This northerly flow should help to enhance some isentropic lift as winds above the sfc increase out of the SW, but the main support for lift will come from upper level dynamics with strong shortwave and upper level jet. This system will bring limited moisture return from the Gulf with pcp water values reaching up around .6 inches, but the strong dynamics aloft will help to produce pcp across the area. The best support will remain just north of our local forecast area, but should reach just along our NW to NE boundaries. The temperatures and dewpoint temps were holding just around freezing overnight with a decent layer of high clouds across the area. The column will continue to moisten up aloft with pcp finally making it to the ground Wed morning west of I-95, mainly between 8 and 10am. Sfc temps will be on the rise through the morning and should rise into the mid 30s to lower 40s. At the same time, temps aloft will drop. This type of column will support either rain or snow. As it looks now, the rain and warmer sfc temps should allow for melting of the snow and do not expect much in the way of accumulations across most of the area. Have increased max amts up between 2 and 3 inches across northern portions Marlboro and Robeson counties, with greater amounts north of local forecast area. Still looking like northern portions of Marlboro into Robeson have greatest chc of snow accumulations as burst of snow early to mid aftn may help to produce the best accumulations closer to 3 inches. The brunt of the pcp will come during the warmest time of day which should act as a limiting factor for accumulations. As the pcp spreads toward the coast it will start as rain most likely between 3 and 5 pm and with the best lift to the north, expect QPF to be much less as you head toward the coast and into coastal SC and expect primarily rain with just a chc of snow in the evening as the cold air moves in and the moisture moves out. All pcp should end mainly as snow before midnight. Very cold air will follow with deep CAA and gusty northerly winds tonight. Temps will drop down near 20 by Thurs morning with wind chills in the lower teens. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...The deep upper air trough will be off the coast by sunrise Thursday. Drier westerly mid and upper level flow guarantees a couple of days of clear skies and dry weather. Surface high pressure moving eastward along the Gulf Coast will build across Georgia and northern Florida by Friday, then push out into the Atlantic Friday night. Temperatures will remain well below normal Thursday when highs should only reach 40-45 degrees. Warm advection up at 850 mb won`t really show up at the surface until Friday, so Thursday night will again be quite cold with lows in the 20s down to the beaches. By Friday highs should reach the mid 50s which is almost up to normal levels for mid-January. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 300 PM Tuesday...Surface high will shift east for the weekend, moving offshore. Very dry air in place, precipitable water will be under a quarter inch Sat, ensure the region remains dry. Temperatures will start warming Sat as weak low level warm advection begins. The progressive mid-level pattern, responsible for the surface high`s rapid shift east, will become a little more amplified as a southern stream shortwave moves along the Gulf Coast this weekend. The wave weakens/opens up as it lifts into the southeast and it seems unlikely that it will be accompanied by any rainfall as it passes late Sat night and Sun. Weak 5h ridge starts to build over the western Atlantic early next week which, coupled with low level warm advection, leads to a warming trend Sun and Mon. Best precip chances during the period continue to be associated with cold front crossing the area late Mon or Mon night. Parent low remains displaced well north of the area, moving across the Great Lakes and southern Canada. Although there is a brief period of moisture return ahead of the front, moisture will be limited and current chc pop Mon and Mon night seems reasonable. Cold advection is limited behind the front as the 5h trough lifts northeast instead of moving overhead. Lack of cold advection combined with the return of the 5h ridge over the western Atlantic will keep temperatures near to slightly above climo in the post front environment. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... As of 12Z...Previous TAFs on track with only minor tweaks to timing. Cold front approaching from the west will begin to lower ceilings at the inland terminals around sunrise. Precip will begin around late morning, likely starting out as rain with temps in the 40s. Time height shows cold air pouring in at 850 mb, with temps around -4C by mid to late afternoon at the inland terminals. Light snow will lower visibilities in the IFR range, perhaps lower at time. Precip will not reach the coast until early evening, changing to snow briefly before ending around midnight. Clearing should advance across the area from west to east late in the forecast period. Extended Outlook...VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Wednesday...Small Craft Advisory remains in effect for all waters today through Thursday morning into early afternoon. A cold front will cross the waters later today followed by a strong northerly surge with gusty winds up to 25 to 30 kts overnight into early Thurs. This will produce a rapid rise in seas this evening up to 4 to 7 ft peaking around daybreak Thurs. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...Low pressure will move away from the U.S. East Coast Thursday while high pressure builds east along the Gulf Coast. This will lead to decreasing northwest winds during the day Thursday, backing more westerly Thursday night and Friday as the high moves into Alabama and Georgia. The high will move off the Georgia coast Friday night. Short-period wind waves will be supplemented by a 2-foot 10 second swell from the east-southeast through the period generated by a broad zone of northeasterly winds between the Caribbean and Bermuda. LONG TERM /SATURDAY THROUGH SUNDAY/... As of 300 PM Tuesday...Weak surface high will quickly shift east over the weekend. Southwest flow drops to around 10 kt by Sat morning. The center of the high expands over the western Atlantic with the surface pressure gradient becoming ill- defined. Winds will drop under 10 kt late Sat night and remain light and variable Sun with the surface ridge axis in the region. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Winter Weather Advisory until 10 PM EST this evening for SCZ023-024. Winter Storm Warning until 10 PM EST this evening for SCZ017. NC...Winter Weather Advisory until 10 PM EST this evening for NCZ096-105. Winter Storm Warning until 10 PM EST this evening for NCZ087. MARINE...Small Craft Advisory from 7 PM this evening to 7 AM EST Thursday for AMZ254-256. Small Craft Advisory from 7 PM this evening to 1 PM EST Thursday for AMZ250-252. && $$ NEAR TERM...RGZ SHORT TERM...TRA LONG TERM...III AVIATION...43

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