Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 130305 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1005 PM EST Fri Jan 12 2018 .SYNOPSIS... Showers and possibly a few thunderstorms will occur ahead of a cold front through this evening. Cold and dry air will move into the area during the weekend as high pressure slowly wedges down the coast. An area of low pressure will develop off the Carolina coast and may bring a period of wintry precipitation Tuesday night into Wednesday evening. Arctic air will reach the Carolinas Wednesday and Thursday with a slow moderation in temperature beginning Friday. && .NEAR TERM /THROUGH SATURDAY/...
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As of 1000 PM Friday...Scattered convective elements within a larger area of rain concentrated itself into quite a squall line near Cape Fear this evening. Wind gusts out at the Frying Pan Shoals buoy reached 62 mph, with 44 mph gusts reported at the Weatherflow sensor at Federal Point in southern New Hanover County. Although the ILM ASOS only gusted to 35 mph, we`re estimating winds reached 45 mph a half mile away at the NWS office at the airport. This convective activity was feeding off unstable air near the Gulf Stream where CAPE values of 500-1000 J/kg exists. Farther inland, a shallow convective shower that was tracked across Florence and Dillon counties weakened as it moved through western Robeson County just before 8 PM, but not before produced a small area of wind damage 4 miles east of Pembroke. Please see our local storm report for additional details. It`s interesting to note this occurred in a very strongly sheared airmass with instability of 200-300 J/kg existing in a layer elevated several thousand feet above the surface. With the squall line now offshore, drier and more stable air aloft is already building across the area. This means our rain is essentially over. Low stratus clouds and fog along the coast will take another hour or two to dissipate, with perhaps some fog hanging on across the coastal waters until after midnight. The actual cold front is just now moving into western South Carolina, but when it arrives late tonight dewpoints and temperatures will begin to fall quickly.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...Cold weather is back. Strong high pressure will build in behind exiting cold front Sat night as deep mid to upper trough digs down over the eastern CONUS. This will advect plenty of cold and dry air into the Carolinas through the latter half of the weekend. The 850 temps will continue to plummet down to - 4c and remaining between -2 and -4c through the period. Pcp water values will be down less than a quarter of an inch. Overall a return to very cold and dry weather. Any clouds will be scoured out early on and expect plenty of sunshine on Sunday. There may be a return of some passing clouds Sun night as a short wave rounds the base of the mid to upper trough, but too dry for any pcp through the period. Temperatures will be down between 25 and 30 most places Sat night and will fight to reach around 40 on Sunday. Sunday night temps will drop into the lower 20s most places. Brisk northerly winds will make it feel even colder Sun morning, as if in the teens while Sun night will be colder in general but less of a wind chill. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 300 PM Friday...Cold weather will persist through the period with a risk for wintry precipitation Tue night into Wed eve. High pressure will wedge down the east coast Mon with a coastal trough developing offshore during Mon and Mon night. Low pressure is expected to develop off the Carolina coast, but where and when this area of low pressure initiates is still a big question. Should the low develop close enough to the coast, then there will be a risk for precipitation along portions of the more immediate coast later Mon and Tue and possibly into Tue night. There is some potential that any precipitation which does clip the coast in direct association with the developing coastal low and trough could be a wintry mix. Confidence is a little higher that a vigorous upper low and associated strong shortwave energy will move across the eastern Carolinas and provide ample lift in the wake of the surface low. The column should be sufficiently moist and cold enough to support frozen precipitation, at least for a portion of the time. Timing is not quite nailed down, but the GFS has trended further S with the upper low and slowed its timing and is now in better agreement with the Euro in showing the brunt of the upper level support pivoting across the FA Wed into Wed eve. We have included POPs for Tue eve and night through Wed afternoon/eve, first starting across our inland most zones and ending lastly across the Cape Fear area. Snow is favored, although precipitation should tend to at least mix with rain during the warmest part of Wed afternoon before any left over precipitation trends back to snow. For obvious reasons, including the time range we are dealing with and model inconsistencies, we can not accurately forecast accumulations at this time. However, there is a good chance that some accumulation will occur. Generally speaking, in these scenarios, we do not receive significant precipitation. However, should the coastal low develop closer to the coast, then more significant QPF is possible. We will continue to monitor and later forecasts should provide more refined details. Highs will be mainly in the 40s Mon and Tue. The peak of the cold air advection this period should keep highs closer to the upper 30s to around 40 Wed and Thu with some temp recovery likely on Fri. Lows will be in the 20s Mon night and some 20s to around 30 Tue night. Lows will drop to the teens for most of the area Wed night and it should be about as cold Thu night. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 00Z...First round of showers has moved through the area with the next batch, associated with a rapidly moving cold front, will sweep through the region over the next 4-5 hours. An isolated thunderstorm is possible, but left it out of the TAFs for now. Gusty southerly winds will shift to the west late tonight. Expect intermittent IFR conditions due to heavy rain and occasional low ceilings. Conditions will rapidly improve from southwest to northeast after 03Z. Look for predominately MVFR ceilings on Saturday with a biting northwest wind. Extended Outlook...VFR. Gusty west to northwest winds will occur in the wake of a dry cold frontal passage Sat afternoon. The next cold frontal passage will occur late Tuesday with MVFR conditions possible due to isolated pcpn. && .MARINE...
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NEAR TERM /THROUGH SATURDAY/... As of 1000 PM Friday...Two weather issues on the coastal waters tonight have been fog and severe thunderstorms. An impressive squall line developed near Cape Fear this evening producing 54 knot wind gusts at the Frying Pan Shoals buoy. This activity is now well east of Cape Fear, and dry weather is anticipated overnight. Dense sea fog most of the day has become smaller in areal extent behind the squall line, but may continue for another hour or so. Drier air advecting in from the west should dissipate the last of the fog by 1 or 2 AM. Southwest winds 15-25 kt will veer more westerly late tonight as the surface cold front, now moving through western South Carolina, reaches the coast. Strong southerly winds all day plus this evening`s squall line have left very large seas in their wake. At last check it`s 6-7 feet nearshore and 10.5 feet out at Frying Pan. These seas should diminish only slightly overnight as winds turn more westerly. SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...Strong dry and cold high pressure will build down into the waters through the latter half of the weekend. Winds will become northerly Sat evening and remain N with a slight N-NE shift Sun night. A brief lighter off shore wind Sat eve will allow seas to drop down near 3 to 5 ft but the increasing northerly surge up to 20 to 25 kts will produce a rise in seas up near 5 to 7 ft mainly in outer waters. SCA conditions should exist Sat night after midnight and end by Sun aftn. Seas blocked by northerly flow will experience lower winds and seas Sat night into Sun and may experience borderline SCA conditions. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 300 PM Friday...High pressure will wedge down the east coast Mon with a coastal trough developing offshore during Mon and Mon night. Low pressure is expected to develop off the Carolina coast, but where and when this area of low pressure initiates is still a big question. Low pressure should move well NE of the waters Wed night. The highest risk for Small Craft Advisory conditions is Wed night and Thu, but this may flex a little earlier and will be dependent on timing of east coast trough and surface low development. Winds from the N Mon and Mon night will likely back to NW or even WNW for a time Tue and Tue night with NNW or NW winds dominating Wed and Wed night. WInd speeds will be around 15 kt Mon morning, but should trend to under 10 kt Mon night and Tue before reversing higher later Tue night. Wind speeds Wed will likely increase to 15 to 20 kt later in the day before peaking Wed night into Thu morning. Seas will be 4 to 5 ft Mon morning. Seas will subside Mon afternoon and this trend will persist into Tue night. Seas are expected to build on Wed and may reach 4 to 7 ft Wed night.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Dense Fog Advisory until 11 PM EST this evening for AMZ250-252- 254-256. Small Craft Advisory until 5 PM EST Sunday for AMZ250-252-254- 256. && $$ SYNOPSIS...RJD NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RJD AVIATION...DL

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