Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 220138 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 938 PM EDT SAT MAY 21 2016 .SYNOPSIS...
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Showers and a few thunderstorms will move across portions of the area tonight ahead of a frontal system which will move offshore through Sunday morning. An area of low pressure aloft will bring a slight chance of showers Sunday and Monday. Summer-like temperatures and mainly dry weather will develop by the middle of next week with above normal temperatures into next weekend.
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&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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As of 900 PM Saturday...Lightning continued to diminish and clouds have begun to warm as cloud tops have lowered...an indication that the updrafts were weakening. Thus the risk for strong thunderstorms has ended. Scattered showers and isolated thunderstorms will still be present through the remainder of the late eve and into the late night hours along the more coastal areas. Mid-level shortwave energy will approach the Carolinas tonight with one spoke of this energy moving through on Sunday. A surface front is coincident with this shortwave. Clusters of showers and a few thunderstorms were moving across the area this eve. Consensus amongst the high resolution models continue to support the best coverage of showers and thunderstorms moving across the I-95 corridor through 03-04z...and then the remainder of the area...moving offshore around 06-08z. A weak wave of low pressure on the front may allow some showers to persist through daybreak...mainly across the Cape Fear Region...in closest proximity to the weak area of low pressure. Will maintain pops in the 40 percent range for most of the area...lower as you move south across the southern Grand Strand and South Santee River areas...furthest removed from the best upper level support. A frontal system will be moving off the coast late tonight. Light winds and only slowly lowering dewpoints toward morning may result in patchy to areas of significant late night fog...especially in locations where heavier downpours occur.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... As of 300 PM Saturday...The start of this period will feature the upper trof extending down the east coast Sunday morning. The upper trof closes off and nearly becomes a cutoff low depending on your definition. The upper low`s center over the VAs Sunday afternoon is progged to drop southward to a position over eastern NC by daybreak Mon. And remarkably, the models are in pretty good agreement in lifting this closed low northward to basically off the NJ Coast by daybreak Tue. Like spokes on a bicycle wheel, there will be mid level s/w trofs or vorts rotating around this upper low. With decent or o.k. lapse rates, available moisture, and if enough daytime insolation to further aid instability, convective chances should increase ahead and in the vicinity of these rotating s/w trofs. Models are at times different with the timing of their movement across the fa, but nevertheless the threat for convection will exist especially during each day. At night, depending on the strength of the upper s/w trof rotating thru, will likely have to carry low pop convection well into Sun night. In addition...model sounding data indicate 500mb temps drop to -19 degrees C and as a result, small hail from any of the convection will become a possibility. The end result is that this cold core upper low affecting the area Sun thru Mon night means temperatures will average 5 to 10 degrees below normal this period. Normal daytime highs run in the low to mid 80s and night time lows in the lower 60s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 300 PM Saturday...Warm summertime weather forecast for the upcoming week as a pattern more typical for this time of year finally sets up. Upper level low will be migrating off to the northeast on Tuesday as ridging blossoms northward from the Gulf of Mexico. As this happens...surface high pressure will re-center itself off the southeast coast...with a Bermuda High type setup forecast for the remainder of the period. The combination of warm return flow around the surface high and bulging heights beneath the mid-level ridge will create warm and mostly dry conditions as subsidence prevents much in the way of even diurnal convection. The exception still looks like Thursday when a weak impulse will rotate atop the ridge and cause subtle height falls...which when combined with the increasingly unstable airmass as heat and humidity increase...should fire off some storms Thursday/Thursday night. Otherwise...the extended looks very nice with highs and lows slightly above climo under ample sunshine. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 00Z...The main question for this TAF issuance is whether upstream convection will hold together to affect area terminals tonight. At this time...it looks most probable for showers and storms to affect northern and western terminals in the 01Z to 05Z window. Southern terminals should remain unscathed. Otherwise...VFR conditions are expected tonight until MVFR fog develops after midnight. Fog should burn off by 14Z with VFR conditions expected for the remainder of the TAF period with isolated to scattered afternoon thunderstorms possible. Light winds tonight will become NW at 5 to 10 KT after daybreak Sunday. Extended Outlook...Possible MVFR conditions on Monday, otherwise VFR. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 900 PM Saturday...A cold front will move across the waters early Sunday morning. A wave of low pressure on this front may slow the front as it pushes offshore. The wind direction will remain from the SW at 10 to 15 kt through late eve...then shift to the W and NW well after midnight. Wind speeds will decrease to 10 kt or less overnight before bumping higher Sun morning. Seas will be mainly 2 to 3 ft. Isolated to scattered showers and isolated thunderstorms are expected to move across the waters late tonight. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 PM Saturday...The sfc cold front will slowly drop south of the area waters early Sunday morning. Winds behind the cfp, will veer to the NW and NNW Sunday and persist in this direction thru Monday. For Monday Night, with the upper low now lifting to the north, away from the area waters, the sfc pressure pattern will become less dominated by the cyclonic flow associated with this upper low. This will result in winds slightly backing to a westerly direction. The sfc pg thru Monday will remain weak across the ILM SC waters, and 1 step hier than weak across the ILM NC Waters. This will yield wind speeds in basically the 10 to 15 kt range...with the hier side of this range across the ILM NC Waters. Significant seas will range between 2 and 4 feet thru the period, with the 4 footers occurring primarily early in the period, basically thru early Monday and mainly across the ILM NC Waters. Dominating periods will basically range between 7 and 9 seconds. With an offshore wind, wind driven waves will be minimal due to the limited fetch. As a result, an ese 1 to 3 foot ground swell will become the primary significant seas producer, hence the hier dominating periods. Upper s/w trofs rotating around the upper low will sporadically move across the area waters thruout this period. Dynamics from these will be enough for convection to also sporadically occur. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Westerly winds Tuesday will transition to the S/SW Wednesday and then remain from that direction for several days as high pressure offshore becomes the dominant feature. The gradient in the vicinity of this high will be weak...so wind speeds will be around 10 kt each day regardless of direction. Although a SE 8-9 sec swell will amplify within the spectrum...especially late in the period...wave heights will remain just around 2 ft Tue/Wed...rising to 2-3 ft late thanks to that growing aforementioned swell.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...JDW AVIATION...RAN

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