Area Forecast Discussion
Issued by NWS Wilmington, NC

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897 FXUS62 KILM 191632 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1232 PM EDT Thu Apr 19 2018 .SYNOPSIS... A dry cold front will bring one more day of breezy, warm weather to the Carolinas today. Chillier temperatures are expected tonight through Sunday as Canadian high pressure builds into the Eastern U.S. Low pressure will approach from the west Monday and Tuesday next week bringing rain back to the Carolinas. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1230 PM Thursday...The front has advanced eastward to a line from Newberry SC to Monroe and Southern Pines, NC. Ahead of the front temperatures have risen into the upper 70s and lower 80s, and this necessitates another bump upwards in forecast highs for this afternoon. Forecast highs now include 81 in Lumberton, 82 in Florence, Myrtle Beach and North Myrtle Beach, and 84 in Wilmington. Wind gusts have been bumped upwards to 35 mph with a few spots near 40 mph for the next few hours. This is still below wind advisory criteria. Discussion from 930 AM follows... Quite a few changes were necessary to the forecast this morning. With the cold front only now reaching a line from Hickory-Winston Salem-Danville, that`s going to allow plenty of time for the strong April sunshine to work on the warm prefrontal airmass before the wind shift arrives. I`ve raised forecast high temperatures across the board, but particularly west of I-95 where the slower frontal passage should allow temps to reach 80 degrees by early afternoon, and also along the beaches where the increasing westerly component to the surface winds should prevent a seabreeze from developing. I`ve raised forecast highs at North Myrtle Beach to 80, and at Myrtle Beach to 81, and these highs may occur unusually late in the day for a coastal location given the offshore wind component expected to develop. In between the coast and I-95 temps should rise to 81-84 degrees. Dewpoints currently in the upper 50s should allow some high- based cumulus to develop by late morning and early afternoon. A subsidence inversion already in place aloft should prevent the cumulus from growing very deep, so a dry forecast continues. Wind gusts of 30-35 mph will mix down during the warmest part of the day as shown on recent GFS, NAM, and RUC forecast soundings. For tonight cold advection behind the front should keep thermal profiles steep and wind speeds may be slow to come down. Since there may not be a significant nocturnal inversion until late I`ve raised lows a degree or two, with lows expected to range from 39-44 from NW to SE.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 330 AM Thursday...No pcpn this period. Just cool high pressure ridging across the area from the Great Lakes Fri thru Sat and into Sun. Low RHs through the atm column, and aided by the scouring effect from W to NW downslope winds off the Appalachians will result with no clouds Fri thru most of Sat resulting in blue skies and sunshine each day and a clear Fri night. High level clouds will push across the area either late Sat or may hold off until Sat night. With high pressure having it`s origin across central Canada, expect temperatures thruout this period to run up to 10 degrees below normal for both maxes and mins of these 2 days and nights. Sat morning lows may drop into the upper 30s across those sheltered locations inland. If winds decouple early Sat morning then the possibility of Frost development may occur if mins drop even lower. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...Temperatures will remain below climatology through the period while the weather becomes increasingly unsettled. The Saturday through Sunday should be rain-free as high pressure is passing by to our north. As this happens a cutoff upper low will move across the Gulf states leading to cyclogenesis. Clouds and perhaps rain will then overspread the region Sunday night. With the high holding on to our north there will be a good overrunning surface with warm advection over the top. This will favor an appreciable QPF event, especially paired with the overall slow motion of the system; so much so that rain may last into Wednesday. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 17Z...A dry cold front will push through the region today. Good southwest gradient ahead of the front. Winds will shift to the west post frontal. Cold air advection will arrive by mid to late afternoon, with winds continuing to back to the west northwest. Tonight, cold air advection will continue with a large diurnal swing in temperature. Too dry to support fog. Friday, continued northwest flow with cooler temperatures. Extended outlook...VFR through Sunday. MVFR is possible at times Monday through Tuesday morning with rain in the area. && .MARINE...
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NEAR TERM /THROUGH THURSDAY/... As of 1230 PM Thursday...The morning low level jet has dissipated, however winds ahead of the front remain quite strong. Wind directions at Wrightsville Beach and Southport indicate a seabreeze is attempting to develop, however increasingly westerly winds should shut this down shortly. Buoys show sea heights have fallen very little from earlier this morning, and I`ve held onto larger forecast values through the afternoon, particularly between North Myrtle Beach and Cape Fear where westerly winds still develop a long effective fetch across Long Bay and 5 to 7 foot waves are now expected to linger. Discussion from 930 AM follows... Several changes are necessary to the forecast with this morning update. A cold front currently back across western North Carolina should reach the coastline late this afternoon and will push out across the waters before sunset. Strong southwesterly winds earlier this morning gusted over gale force, and 25-30 knot wind gusts measured through 8 AM are beginning to diminish now that the nocturnal low-level jet stream is dissipating. Expect southwest winds 15-20 knots to veer more westerly this afternoon, probably preventing a seabreeze circulation from developing. Once the front arrives, winds should veer northerly with another surge of stronger winds developing this evening and lasting through the night. The Small Craft Advisory has been extended to cover residual strong winds this morning and large seas currently reported as high as 7 feet at the CORMP buoy south of Southport, and the anticipated redevelopment of strong winds behind the front tonight. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 330 AM Thursday...SCA conditions likely at the start of this period as North to Northeast winds peak in the morning at 15 to 25 kt and drop relatively quickly to 10 to 15 kt during Fri afternoon. A bubble high may temporarily develop across the area Fri night which will further reduce winds to around 10 kt. This bubble high will wash out as ridging from the high`s center over the Great Lakes re-asserts itself across the area waters resulting with NE-ENE winds around 15 kt. Significant seas will peak at the start of this period with 3 to 6 foot seas. As winds slowly diminish this period, significant seas will follow suit especially with no real ground swell to affect the local waters. Thus wind driven waves at 4 to 6 second periods will dominate this period. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Monday...Large area of high pressure passing by to our north over the weekend. Initially this will bring fairly light NE winds but as the high moves farther east and an area of low pressure approaches the flow will turn easterly and wind will accelerate. Conditions should deteriorate to Advisory levels Sunday night. Additionally some fairly heavy rain will lead to considerable visibility restrictions adding to the hazard level of the marine environment.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 9 AM EDT Friday for AMZ250-252-254- 256. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...DCH LONG TERM...MBB AVIATION...DL MARINE...

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