Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 201155 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 755 AM EDT Thu Oct 20 2016 .SYNOPSIS... Warm and dry weather will continue through today. A strong cold front will move through Friday, bringing significant cooling over the weekend. A slight warming trend is expected Monday before a secondary and dry cold front sweeps off the coast Monday evening. High pressure will build down from the north behind cold front through the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 600 AM Thursday...One more full day of summer-like conditions with low to mid 80s for highs with a few upper 80s well inland away from the effects of the mesoscale sea breeze which does progress inland, just not far enough. Stayed closer to the slightly hier european mos guidance due to its superiority across the other model mos guidances with this weather pattern. This also includes the european mos for tonights lows which is also running slightly hier than the other mos`s. The question for tonight is the possibility of a low level jet that will keep it mixed to the sfc. At this point, think the sfc based inversion that develops after sunset will become just strong enough to prevent the mixing. Therefore, have included patchy fog during the pre-dawn Fri hours. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 330 AM Thursday...The cold frontal passage during Friday and the influx of the coolest air of this autumn season will be the story line for this short term period. A change in the patter n aloft takes place during this period. The upper ridge affecting the FA during the past week will succumb to an amplifying s/w trof from the west which has its roots in the Rockies. A northern stream s/w trof will hook up with main s/w trof and result in a nearly full latitude trof that goes negatively tilted by Saturday morning. This progressive flow sfc and aloft will push the sfc cold front rather quickly across the FA with low chance pops along it. The tstrm parameters are borderline...mainly the further north you are located along the cold front with better dynamics aloft. Thus will include isolated tsra for mainly the ILM NC CWA and a small northern portion of the ILM SC CWA...elsewhere will be shra. The time frame from west to east for the cfp and pcpn to occur runs from 1000AM to off the ILM CWA Coast by 600 PM. Not much wind ahead of the cold front but afterwards look for gusty NW winds that run from late Fri thru Saturday. The tightened sfc pg combined with excellent CAA as seen thru model partiaL thickness schemes and just temps 850mb temps. Winds will stay active thru Saturday due to a 1025+ mb modified Canadian High pressure which its center drops to the Gulf Coast States by daybreak Sun. Just not close enough for a good radiational cooling night. As for temps, looking at 70s to lower 80s for Friday`s highs ahead of the cold...with highs on Sat widespread 60s, a drastic change from this past week! Saturday mornings lows expect widespread mid to upper 40a,and Sunday`s lows in the lower 40s with possible upper 30s inland depending if the FA`s winds can decouple. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 AM Thursday...A deep N-NW flow will continue to usher in cold and dry air through the latter half of the weekend as high pressure remains sprawled across the southeast. Pcp water values down near a quarter of an inch will rise slightly Sun night into Mon as winds back to the W-SW as high pressure gets suppressed south. A dry cold front will drop down from the north by late Mon with high pressure building down from the north behind through mid week. Temps a good 5 to 10 degrees below normal early Sun will rebound late Sun into Mon back toward normal but will get knocked back down with a reinforcing shot of cool and dry air behind front by Tuesday. Overall expect plenty of October sunshine with overnight lows below 50 most days and afternoon highs below 70 except Mon. Latest guidance showing coldest temps below 40 just before daybreak early Sunday morning. Temps near the beach will be slightly warmer due to warmer ocean temps. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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As of 12Z...Anticipate MVFR/IFR due to fog/low cigs again late overnight into Friday morning. Otherwise expect VFR. Conditions are already improving to VFR after widespread fog and areas of low cigs created MVFR/IFR earlier this morning. Light east-southeast winds will continue today with nearly clear skies. Overnight, ideal radiational cooling conditions return, with the development of fog and areas of low cigs anticipated to create MVFR/IFR. Extended Outlook...Potential for brief MVFR conditions in -SHRA and clouds on Friday, especially late in the day. Otherwise, expect VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 600 AM Thursday...Winds to start out variable around 5 kt. Will identify the most dominate wind direction in lieu of going variable. The expanding synoptic offshore low, NE of the Bahamas by this evening, will result in a slight increase to the e to ne winds later today backing to northerly tonight. With speeds only increasing to 5 to 10 kt or around 10 kt. By late tonight...the expanding low...will begin its turn toward the n or nne. Significant seas will be at their minimum this morning followed by an increasing 9 to 11 second period swell from the offshore low late this aftn thru tonight. Seas around 2 ft this morning will build to 2 to 4 ft beginning late this aftn but majority of it occurring during tonight. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 330 AM Thursday...For Friday thru Friday Evening, the main story will be the approach and passage of the cold front. Ahead of the front winds will be wsw to wnw direction at 10 to occasionally 15 kt. The cfp will occur late this afternoon and early evening with winds after the cfp increasing from the NW at 15 to 25 kt with gust around 30 kt. Could see gusts approaching 35 kt late Friday night or early Saturday during the height of the CAA combined with the well tightened sfc pg. Winds will diminish-some Saturday night as the sfc pg loosens a bit. With the center of the high progged to be over the Gulf coast states by Sun morning, winds across the area will remain active. Significant seas will initially be influenced by the well offshore Low with 2 to 4 foot or 3 to 5 foot seas affecting the local waters and mainly in a 9 to 10 second period easterly swell. After the cfp and thru the remaining short term period, the long period swells will combat the building nw wind driven waves. By Saturday thru saturday night, the 3 to 6 second short period wind wave will finally dominate the local waters. Seas could reach 7 to 8 ft across the outer waters and just offshore from Cape Fear due to the interaction of the incoming easterly swell and the increasing offshore wind waves. But overall, looking at 3 to 6 ft on Saturday subsiding to 2 to 5 ft...with the lower seas near shore. LONG TERM /SUNDAY THROUGH MONDAY/... As of 300 AM Thursday...Winds will lighten up and back to the W-SW Sunday through Monday as high pressure shifts closer overhead and weakens. Seas will subside through early Mon down to 2 to 3 ft. A dry frontal passage late Monday will bring W-SW winds 15 KT or less Monday. Another surge of northerly winds overnight Mon into early Tues may push seas up towards SCA thresholds on Tues. && .TIDES/COASTAL FLOODING... As of 600 AM Thursday...A Coastal flood warning may be needed for this afternoon`s high tide along the banks of the Lower Cape Fear River from Wilmington southward to the river`s mouth. Water levels are forecast to reach moderate flood thresholds, greater than or equal to 6.7 ft MLLW during this afternoon`s high tide. Each successive high tide will likely require either a coastal flood warning or advisory. Of the 2 high tides per day, the afternoon`s high tide will be the higher of the 2 through Saturday. High Tide Times and the forecast water level for the downtown Wilmington gage... 1:55 PM on Thu Oct 20...7.0 ft MLLW. 2:22 AM on Fri Oct 21...6.6 ft MLLW. 2:57 PM on Fri Oct 21...7.0 ft MLLW. 3:23 AM on Sat Oct 22...6.1 ft MLLW. 3:56 PM on Sat Oct 22...6.5 ft MLLW. Here are the flooding thresholds based on the downtown Wilmington Gage on the Lower Cape Fear River... Minor flooding......5.50 ft MLLW to 6.69 ft MLLW. Moderate flooding...6.70 ft MLLW to 7.99 ft MLLW. Major Flooding......8.00 ft MLLW && .EQUIPMENT... As of 600 AM Thursday...The ASOS at the Lumberton, NC airport (KLBT) has no power and the emergency generator which had maintained power since Hurricane Matthew has run out of fuel. Observations and climate data from Lumberton will remain missing until further notice. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RGZ NEAR TERM...DCH SHORT TERM...DCH LONG TERM...RGZ AVIATION...SGL is the U.S. government's official web portal to all federal, state and local government web resources and services.