Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 261114 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 714 AM EDT Wed Jul 26 2017 .SYNOPSIS...
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Drier weather will work into the area behind a cold front today. The front will dissipate to our south on Thursday. Mainly isolated showers and thunderstorms will become numerous Friday into Saturday ahead of an unseasonably strong cold front. Strong to severe thunderstorms will be possible later Friday and Friday night. Much drier air is expected in the wake of this system early next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 600 AM Wednesday...A cold front was running right along the South Santee River and will drift further south through today. A mid to upper trough will run from GA to the east northeast into the Atlantic. Low pressure developing and trying to cutoff at the base of this trough over GA/SC will produce low pressure extending down to the lower levels. This will produce a deep NE to E flow through today and will also bring drier air and subsidence down over NC and into SC by later today into tonight. Initially, this boundary, along with the sea breeze will remain the focal point for convection through today. An area of lower clouds was easing south behind the front while isolated thunderstorms were developing along and just south of the front. Expect lower clouds to break up through the morning and isolated to scattered convective development to be focused along the cold front, sea breeze front and any localized boundaries. Therefore the best chc of thunderstorms will be across SC and along the coast up to Cape Fear while greater amounts of sunshine and drier air can be found over much of NC and N and NW portions of South Carolina. The NE to E flow behind front will keep temps below 90 most places today. Dry air will slowly work its way into the area, especially in the mid to upper levels with clearing skies developing from N to S into tonight. Pcp water values will drop below 1.25 inches by tonight. Guidance shows dewpoint temps dropping to near 70 or just below through late this afternoon into tonight. This will allow overnight lows to fall into the lower 70s across much of the inland areas under mainly clear skies.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...A cold front will be in the process of dissipating to our S on Thu. Modest ridging aloft going into Thu erodes rather quickly and is replaced with increasing troughiness. Then as this trough deepens across the Eastern third of the CONUS, it helps to drive a cold front southward. This front will be very near our northwest zones by daybreak Sat. The expectation is that Thu will be a day of transition as initially drier air will show some erosion as deeper mositure begins to poke back to the N. Thus, slight chance or chance POPs for showers and thunderstorms appear warranted for mainly our southern zones, highest across the South Santee River area. Convection may begin to blossom offshore Thu night, perhaps skirting portions of the immediate coast. The deep moisture will be feeding N and focusing along and ahead of impressive trough, especially given the time of year. Precipitable water values climb to more than 2 inches and peak at more than 2.25 inches Fri night. At the same time, robust shortwave energy pivots across the eastern Carolinas with a southwest low-level jet of 50 kt impinging on the area and diffluence aloft. This will support increasing shower and thunderstorm activity during Fri with the most widespread coverage late Fri and Fri night and perhaps into Sat. This setup could very well support an organized severe thunderstorm event. The Pattern should be progressive enough to limit excessive rainfall concerns with very high moisture content being mitigated by quick storm motions. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 215 PM Tuesday...An unseasonably amplified upper trough becomes the primary feature and key player for late week and weekend sensible weather. This will translate to elevated rain chances Saturday as this system ushers a fairly strong surface trough across the coast. ECMWF and GFS clear this boundary off the coast into early Sunday, the GFS much stronger. Both suggest therefore some drying and cooling, but of differing magnitude. A blend still brings surface dewpoints into the 60s early next week, helping to take off the bite of high absolute humidity values. A dry mid-level air intrusion will curtail deep convection Sunday through early next week. A few showers could linger and remain favored closer the coast in proximity to higher moisture and the oceanic front, but the overall coverage should trend down Sunday onward. Temperatures will be slightly below normal as cool air advection pushes into the balmy sea air. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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As of 12Z...Drier air continues to seep into the area from the N in the wake of a cold front. This front will stall south of the terminals today and slowly dissolve tonight and Thu. Drying should be just deep enough at KLBT and KILM to keep mention of showers out of the TAF forecast here. Elsewhere, will include VCSH from about 16-00z. There may be a rumble of thunder, but the probability is just low enough to keep thunder out of the TAF forecast at KFLO/KCRE and KMYR. Thunderstorms will be scattered to perhaps numerous across southern portions of South Carolina and points S where the front will reside during peak heating. Will initialize with MVFR/IFR ceilings at all sites. Expect VFR to develop at the remaining terminals in the 14-16z time frame. VFR will continue through the remainder of the valid period, but will introduce few/sct stratus at or below 1 kft after 07-09z. Moisture should be very limited overnight and thus not supportive of ceilings or fog. Extended Outlook...MVFR or lower flight restrictions are likely in association with numerous thunderstorms later Fri and Fri night. Some of the thunderstorms may be strong to severe. Flight restrictions may persist into portions of Sat as well.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 600 AM Wednesday...In the wake of a cold front, the wind direction has shifted to the NE or ENE and we expect this direction to hold across the waters with speeds of 10 to 15 kt. The on shore winds will push seas up from less than 3 ft this morning to 3 to 4 ft later today into tonight. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...A cold front will be in the process of dissipating to our S on Thu. A stronger cold front will be approaching from the N Fri night. A light easterly flow early on Thu will veer to SE and S Thu afternoon. Wind speeds will increase Thu night as the direction veers to SW. SW winds will then persist through the end of the period as they increase to near 20 kt later Fri and Fri night. Seas will build in response to the increasing wind, building from 2 ft Thu and Thu eve to 3 to 4 ft Fri afternoon and 4 to 5 ft Fri night. Small Craft Should Exercise Caution conditions appear likely late in the period. Thunderstorms will be few if any Thu but we do expect them to become numerous during Fri and especially Fri night. LONG TERM /SATURDAY THROUGH SUNDAY/... As of 215 PM Tuesday...Wind direction will become changeable this period, but the good news is that wind-speeds will decrease as a front lays up along the coast then offshore. TSTMS will be numerous along the front into Saturday, so a radar update should be on the checklist for the first part of the weekend. TSTMS will decrease in coverage Sunday, although the Gulf Stream and outer waters may remain unsettled due to the offshore front. Gusts to 20 KT from the SW may persist into Sat morning ahead of the front. Then once the front moves through later Sat and Sat night, the wind direction will shift to the NW and N and then NE on Sun. Wind speeds Sat afternoon through Sun will be on the order of 10 kt. Seas of 4 to 5 ft early Sat will subside to 3 to 4 ft, but a modest NE push may bring some 5 ft seas back across portions of the outermost waters on Sun.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RGZ/RJD SHORT TERM...RJD LONG TERM...MJC AVIATION...RJD

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