Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 150525 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 125 AM EDT Thu Mar 15 2018 .SYNOPSIS... The center of chilly high pressure will build east across the northern Gulf coast through Thursday. Temperatures will be well below normal across the eastern Carolinas and a widespread freeze is expected tonight. Temperatures will warm Thursday and Friday before another shot of cool air reaches the area late Friday night and Saturday. The risk for a few showers will return Friday night and into Saturday, with better chances the first part of the upcoming week. && .NEAR TERM /THROUGH TODAY/... As of 830 PM Wednesday...Main update concerned with latest obs illustrating sfc winds dropping quicker than what`s currently being fcst. This has resulted in sfc temps dropping slightly quicker than planned as sky conditions also improve quicker than what models dictated. Have re-adjusted the overnight wind and temp curve and using latest SUPERBLEND for overnight sfc dewpoints. All of this still points to a FREEZE Warning already in effect for the entire ILM CWA with the potential to see min temps at or below the freezing mark for greater than 8 hrs at any individual place. Of course, if temps drop to the mid 20s across locations with active crops at their most sensitive phase of it`s life, disastrous results may occur if cold prevention is not applied. No changes to the time-line of the Freeze Warning...From 11 pm Wed to 9 am Thu. Previous........................................................ As of 245 PM Wednesday...Temperatures this afternoon have for the most part failed to reach 50 degrees and thus some 15 degrees below climatology. And although temperature guidance is fairly tightly clustered this may be an argument in support for the cooler numbers. The current forecast is a blend of the two and the previous forecast. Tonight`s lows should readily dip below freezing even in areas that do not completely decouple due to a few knots of wind remaining. Freeze Warning remains in effect for all zones. The sense of low level thermal advection reverses to warm atop the surface based layer overnight. This will not be realized until mixing commences tomorrow. A fairly rapid rise in temperatures is expected as the afternoon warms to near seasonable levels. High pressure will remain to our south through the day tomorrow with a light southwesterly flow developing. NW flow continues aloft keeping the sky mostly clear. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 245 PM Wednesday...An upper level ridge across the Plains states will dampen out as it moves eastward and into the Carolinas by late Friday night. One final shortwave rotating around the huge northeastern storm system will exit the Mid-Atlantic coast Thursday night, with cyclonic flow over the Carolinas finally straightening out Friday. Warm advection on steady westerly winds will push 850 mb temps up to +6 to +7C Friday. Although moisture aloft should be increasing, there won`t be enough to prevent plenty of sunshine and highs could soar into the lower 70s inland. High pressure to our south will exit the Florida east coast Friday, but a second weaker high moving across the Great Lakes will push a backdoor front southward and into the area Friday night. All models yesterday were quite bullish with the southward movement of this front, but the new 12Z GFS isn`t quite so sure, stalling the feature near Cape Fear Friday night and then showing it returning northward before daybreak Saturday morning. This appears to be in response to the GFS generating a stronger cyclone across the Ohio River Valley by 12Z Saturday compared to other models. The 12Z NAM and ECWMF still look like yesterday`s idea, so I`ve made only small adjustments to our forecast. If later model runs start to favor the new GFS, Friday night`s low temps would need to be raised by 5-10 degrees and wind directions veered more southeasterly. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 245 PM Wednesday...A warm front is expected to be in the area Saturday morning and it will lift quickly to the north. Low level Theta-E advection will be strong enough to warrant a small chance of showers during the day. Otherwise, temperatures are trending warmer during Saturday compared to earlier model runs, and turning breezy as well. Better rainfall chances Monday into Tuesday, though there is a bit of uncertainty given weak perturbations possible along the old boundary and ECMWF/GFS handling of areas of low pressure, GFS more robust and farther north at this time. Overall temperatures will be at or above normal Saturday, but could drop below for a few periods late weekend/early next week. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 06Z...VFR conditions the next 24 hours at all sites. Once again gusty winds will be the biggest challenge with similar gusts that occurred Wednesday. Also expect less mid level cloud cover. Extended outlook...VFR. Slight chance MVFR Sat night/Sun. MVFR/SHRA likely Mon.
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&& .MARINE... NEAR TERM /THROUGH THURSDAY/... As of 830 PM Wednesday...Will be going into a short abatement of winds and lowering seas tonight into daylight Thu. Than a ramp back up in both winds and resulting seas later Thu due to the sfc pg re-tightening. This next re-tightening phase may result in Gale Force wind gusts becoming more common later in the day on Thu and into Thu evening. The common offshore trajectory in the winds will keep the fetch limited for wave growth. The exception will be when wind directions become WSW to WNW. The seas between Murrells Inlet to Cape Fear will have the best fetch for waves to grow given these directions. In addition, a fading 1 to 1.5 foot, Easterly ground swell at 12+ second periods will still provide input, albeit very small given the hard offshore winds. Previous........................................................ As of 245 PM Wednesday...Gusty NW flow to continue but abate as upper trough lifts out and its main impulse moves off the coast. Wind will gradually shift from NW to W and then SW by late Thursday. The gradient gets a bit stronger as Thursday wears on due to high pressure building into Florida and low pressure that is hesitant to leave New England/eastern Canada. This ticks winds back into Advisory realm. Have decided that the sub- advisory break will be short enough that have just run flags right through the period. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 245 PM Wednesday...High pressure near the Florida east coast Thursday night will move offshore Friday and Friday night. While this means offshore winds for the Carolinas, a strong upper level disturbance whipping across the Mid-Atlantic region Thursday evening will tighten the pressure gradient substantially across our area. Westerly winds as strong as 30 knots with some higher gusts are expected Thursday night, with gale force winds expected out beyond 20 miles from shore. Seas will build as high as 5-7 feet inside 20 miles from shore with short, choppy wave periods. Winds will diminish quickly Friday morning as the trough moves away from the East Coast, but the next concern is a backdoor cold front pushed southward by the trough. Models yesterday showed this feature making quick progress southward across the area, however our normally reliable GFS model now stalls the boundary near Cape Fear Friday night and shows it returning northward before daybreak Saturday morning. Other models like the NAM and ECMWF appear much more like yesterday`s idea, and we`re making only small changes to the forecast at this time. .LONG TERM /SATURDAY THROUGH MONDAY/... As of 245 PM Wednesday...A warm front will lift north of the waters Saturday morning. Warm frontal passage will immediately be followed by an increasing southwesterly fetch and possibly a return of Small Craft conditions from late Sat morning into Saturday night. During Saturday night/Sunday morning, a cold front may push southward across the waters, stalling south of the waters Monday. As a result, the post frontal winds will be temporarily from the north Sunday before veering to an east or southeast direction Sunday night into Monday. A southerly fetch could develop again during Monday ahead of the next system. Steep waves are possible in the southwest fetch Saturday before subsiding a notch Sunday into early Monday. Seas are expected to build again during Monday. && .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...Freeze Warning until 9 AM EDT this morning for SCZ017-023-024- 032-033-039-054>056-058-059. Fire Weather Watch from 8 AM EDT this morning through this afternoon for SCZ017-023-024-032-033-039-054>056-058-059. NC...Freeze Warning until 9 AM EDT this morning for NCZ087-096-099- 105>110. MARINE...Small Craft Advisory until 11 PM EDT this evening for AMZ254- 256. Small Craft Advisory until 6 AM EDT Friday for AMZ250-252.
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&& $$ SYNOPSIS...MBB NEAR TERM...DCH/MBB SHORT TERM...TRA LONG TERM...SRP AVIATION...SHK MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.