Area Forecast Discussion
Issued by NWS Wilmington, NC

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485 FXUS62 KILM 230640 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 240 AM EDT Mon Oct 23 2017 .SYNOPSIS...
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A strong cold front will approach from the west today and slow, finally moving completely offshore Tuesday afternoon. Showers and thunderstorms are expected along and ahead of the front with the possibility for a line of strong to severe thunderstorms late this afternoon and this evening. In the wake of the front, dry and cool air will filter in mid week as Canadian high pressure takes hold. Showers in association with developing low pressure may return to the area this weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 300 AM Monday...Weak low-level convergence off the SC coast associated with a subtle surface trough is helping to generate widely scattered light showers, which will stream northward through the pre-dawn hours. Shower activity will increase from west to east through the afternoon well ahead of a strong, negatively-tilted 500 mb trough, which will be lifting across the OH river valley today. A 40-50 knot southerly low-level jet will traverse the CWA in the late afternoon and early evening, and SPC has included the CWA in a slight risk for severe thunderstorms. There will be potential for damaging winds gusts as convection may strengthen in the moist and marginally unstable air in place ahead of the cold front. Wind fields will also become supportive of rotating updrafts and provide the potential for a few tornadoes. The front will enter the western CWA around 06Z Tuesday, and should be approaching the coast by 12Z. Even outside of convection, southerly winds will gust to 20-25 mph this afternoon as the gradient tightens up ahead of the front. Max temps, and therefore destabilization may be limited by cloudiness generated by upstream convection early in the day, but temps will still climb to the upper 70s to near 80. Lows Monday night will range from around 60 inland to around 70 along the coast.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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As of 300 AM Monday...Deep low pressure will be located across the Great Lakes Tue with a strong cold front draped S across the Eastern Seaboard. This front is expected to exit the eastern Carolinas later Tue morning through early afternoon. The punch of dry air behind this negatively tilted system should cut off any showers across the I-95 corridor by or just after first light Tue. However, given the orientation of the system, it may take considerably longer before the last of the showers and some thunderstorms move completely offshore with the showers persisting into the afternoon along the Cape Fear coast. The strongest low level jet will have shifted well N of the area Tue morning and we do not expect severe weather on Tue across the eastern Carolinas. We will see dewpoints drop in the wake of the front with dry air being reinforced later Tue night into Wed as the wind direction shifts from SW and W to NW. Dewpoints will drop 20 to 30 degrees, bottoming out in the upper 30s to around 40 during the later half of this forecast period. Skies will be clearing on Tue, first across inland areas with thick cloud cover hanging on longest along the coast, especially the Cape Fear coast where it may take a good part of the afternoon before skies begin to clear. Thereafter, we do expect mainly clear skies throughout. Highs on Tue will be in the mid and upper 70s with the cold advection kicking in strongly by Wed, highs will only reach the mid to perhaps upper 60s. Lows Tue night will be in the mid and upper 40s inland and mainly lower to mid 50s at the coast with 40s throughout Wed night. At this time, it does not appear it will get cold enough, especially given the warm soils, for any patchy inland frost to develop with this cold snap.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 230 PM Sunday...Initial portion of the Long Term looks to be dry as high pressure transits east across the eastern Carolinas in the wake of a cold FROPA. Showers moving in advance of the next cold front may impact the area as early as Saturday, but model solutions are still quite divergent as far as timing goes, with the ECMWF holding off on FROPA until after the weekend and the GFS being earlier. So, will limit pops to slight/low chance for this weekend until the picture becomes clearer. It is possible that the weekend may also end up dry. Temperatures will start off below normal for late October, warming to more climatologically-correct levels by Friday.
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/... As of 05Z...MVFR ceilings will overspread the area from south to north through daybreak, along with isolated light showers. Very localized IFR/LIFR may impact KILM over the next few hours. Ceilings will lower and southerly winds will become gusty through the day Monday ahead of a cold front, which is expected to be on the doorstep of KFLO/KLBT by 06Z Tue. Showers will become numerous by mid to late afternoon inland, and along the coast by evening, and a few tstms will be possible. Stronger storms will be capable of producing wind gusts to 30 knots, but confidence in timing the strongest convection is low at this point. Extended Outlook...Intermittent IFR conditions are possible through Tuesday morning. Becoming VFR by midday Tuesday. VFR Wednesday through Friday. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 300 AM Monday...Latest buoy observations indicate southeast winds generally around 15 knots across the area waters, and these will veer to the south and increase through the day as the pressure gradient tightens well ahead of an approaching cold front. The front is not expected to move off the coast until after daybreak Tuesday, but winds and seas will build to Small Craft Advisory thresholds by early this afternoon. No changes will be made to the advisory that is already in place, which is in effect beginning at 2 PM today. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 300 AM Monday...Small Craft Advisory conditions should be waning on Tue with seas dropping below 6 ft across the outermost waters, lastly across the northern waters during the afternoon. Seas will be mainly 4 ft Tue night and 3 to 4 ft for the remainder of the period. SW winds will be weakening across the waters Tue as the strong low level jet shifts N and we expect wind speeds of 15 to 20 kt Tue morning to diminish to 10 to 15 kt Tue afternoon. The arrival of colder and drier air across the waters should allow wind speeds to kick back up to 15 to 20 kt for much of the remainder of this forecast period as the direction veers to WNW and NW. LONG TERM /THURSDAY THROUGH FRIDAY/... As of 230 PM Sunday...High pressure transiting east across the waters will lead to gradually improving boating conditions with dry weather through the long term. Period starts out with NW winds of 15 to 20 kts and 3 to 5 ft seas in the wake of the previous days FROPA, but expect conditions to be become more favorable as the high moves overhead, with winds of around 10 kts by Friday and seas of around 2 ft.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 2 PM this afternoon to 2 PM EDT Tuesday for AMZ250-252-254-256. && $$ NEAR TERM...CRM SHORT TERM...RJD LONG TERM...REK AVIATION...CRM

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