Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 220514 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 114 AM EDT MON AUG 22 2016 .SYNOPSIS... A cold front will move offshore by Monday morning bringing cooler and noticeably drier air into the Carolinas. This airmass will prevail through the week as high pressure extends along the East Coast. A return to seasonable warmth and humidity will begin next weekend but thunderstorm chances will remain minimal. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 1230 AM Monday...A convective outflow boundary is pushing southward through the area now. The actual surface cold front appears to be pushing through Raleigh now. Dewpoints are still in the 70s along and south of I-85 corridor which may be a clue to the frontal position since the outflow boundary has already shifted our winds northwesterly. No significant changes are needed to the forecast on this last near-term update on the night. Discussion from 1000 PM follows... Lowered POPs across all locations for the remainder of this evening and overnight. The threat for convection has bypassed the ILM CWA. All that is left is an outflow boundary still pushing south across the ILM CWA. Currently it extends from Latta across Bolton and Castle Hayne to Holly Ridge. After its passage, SW 5 to 10 mph winds will become nw 10 to 15 mph for a brief time. Winds will settle back to the w at 5 mph or less after midnight as whats left of the outflow blends back into the ambient environment. Fortunately, instability is lacking and thus do not expect any additional convection to develop along this outflow, and also when the sfc cold front pushes across the area during the pre-dawn Mon hours. previous.................................................... As of 730 PM Sunday...Latest HRRR and HiRes Wrf models indicate the majority of the convection ahead of the cold front will remain north of the FA. The extreme northern portions of the ILM CWA may see the southern fringes of this convection as it pushes east at 25 to 35 mph. At this point, the isolated strong and/or severe tstorm activity will remain north of the FA. Models indicate the cold front will drop south into the ILM CWA after midnight tonight...and likely reach the southernmost portions of the FA by daybreak Monday. A few of the models have it moving quicker and further south of the FA by daybreak Mon but with west to east flow aloft, its southward push will be limited and thus slower by this time. The cooler air mass behind this front will take longer to infiltrate the ILM CWA, likely occurring as a secondary front come late Mon or Mon evening. As a result, have tweaked overnight mins up by 1 to 3 degrees. Cloudiness will mainly be a result of the convective debris and in association of the cool front. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...The potent mid level trough readily apparent in the latest water vapor imagery will swing across early Monday with a westerly flow ensuing at the mid levels. The flow will buckle some through the period with the main feature being a ridge across the midwest. This will drive cool and dry high pressure into the area at the surface. This is a common pattern for our area in the waning days of summer and fall and the first iteration this season is a welcome relief. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Tuesday...Sunny and seasonable on Wed with high pressure well off to our northeast but still extending ridge axis deep into the Southeastern U.S. The ridge axis maintains position but weakens considerably on Thursday, which should lead to another seasonable day. Nighttime lows will creep up a bit due to some moisture entering the boundary layer. The remainder of the period will feature a return of late summer heat (late summer, i.e. not of the magnitude experienced in parts of July) as the high breaks down but ridging aloft holds. The latter should cap all but very isolated diurnal convection as will the fact that we never get into much low level return flow. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 06Z...A large outflow has moved across most of the area, blending the airmass in with the approaching cold front. This makes it hard to distinguish the exact location of the front, but it may not matter as winds will remain from the NW through the overnight at 4-8 kts. This is a cooling and drying wind, so VFR will be the rule beneath sct mid-level cloudiness. Winds will veer to the NE behind the cold front during daylight Monday at around 10 kts, with sct 3-6 kft CU expected in the aftn. VFR will persist through the valid period, with sky conditions becoming SKC inland Monday night beneath continued NE winds with decreasing speeds. EXTENDED OUTLOOK...VFR.
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&& .MARINE... NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 1230 AM Monday...A convective outflow boundary from thunderstorms off the Outer Banks is pressing southward across the Cape Fear waters now. Although northwesterly winds are expected behind this feature, look for winds to remain generally westerly until the actual surface cold front arrives late tonight. Discussion from 1000 PM follows... Southwest flow at 10 to 20 kt will prevail this evening and eventually veer to the west just ahead of the cold front, and then to the wnw after the cool fropa. An outflow boundary will push off the NC mainland beginning at Surf City by 11 PM...and work its way southward before finally blending into the ambient environment. Will se a brief nw to n 10 to 15 kt wind for up to a couple hrs after its passage. It will likely not make it out beyond 10 nm from the coast as it blends into the environment. And it will likely not make it further south of Cape Fear. The overall sfc pg remains tightened thruout this evening, and shows signs of relaxing-some well after the cfp during daylight Monday. Significant seas will basically run 2 to 4 ft, highest south of Cape Fear to Murrells inlet where the better fetch resides given the wind direction. Significant seas will mainly be comprised of the 3 to 5 second period wind driven waves. A 1 foot or less underlying se ground swell at 7 to 8 second periods to remain present. SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Winds will briefly become almost light and variable across the waters Monday before surface high pressure becomes better defined late Monday and persists into Wednesday. Wind speeds will be ten knots or less most of Monday with a synoptic direction of northeast before increasing to the higher end of a 10- 15 knot range early Tuesday. The initial surge could see a few hours of speeds just above this range especially across the outer waters. Seas will increase a bit for Tuesday mainly with the range increasing to 2-4 feet. LONG TERM/WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...A somewhat rare NE wind on Wednesday as high pressure well to our northeast extends a ridge axis into the Carolinas. Wave guidance is showing the NE wind waves and an ESE swell combining for a general 2 to 4 ft. Wind remains NE on Thursday but weakens as the ridge axis does the same. By Friday the gradient will become quite poorly defined as there may be a last vestige of high offshore and a weak piedmont trough. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MBB NEAR TERM...DCH/TRA SHORT TERM...SHK LONG TERM...MBB AVIATION...JDW MARINE...

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