Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 290321 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1121 PM EDT Sun May 28 2017 .SYNOPSIS...
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Thunderstorms will finally exit east of the region around midnight. Otherwise, high pressure centered offshore will extend across the area through Monday. A cool front will approach and enter the area from the northwest and stall across the area during the early to mid week time line. Expect scattered showers and thunderstorms along this front with a string of upper level disturbances enhancing the convective activity.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 910 PM Sunday...SVR Watch 295 continues across the forecast area through 1 AM Monday. The main severe threat is for damaging wind gusts with hail a secondary threat. The convective activity is moving from west to east at 25 to 35 mph. Look for a decrease in the intensity of the storms after it initially pushes thru the sea breeze. This observed with latest reflectivity trends after the storm pushed across the sea breeze in Brunswick County and into a sfc based stable marine layer. However, with flow in the low levels westerly at 15 to 30 kt, the sea breeze bndry will likely get pushed back to the coast along with it`s marine layer weakening over land areas. As a result, expect the latest convection to make it to the immediate coast of both NC and SC with some weakening but should still be able to produce atleast a strong+ wind gust. Due to the relatively fast motion, flooding type rains are not expected unless activity starts to train across the same locations. Have peaked POPs at the likely category during this evening and have the activity exiting east into the adjacent Atl waters by midnight to 1 am edt. Previous................................................ As of 300 PM Sunday...A west to subtle southwest flow will continue at the mid levels through the period. A very broad front extends across the Mississippi Valley well to the west. For our area there appears to be two decent chances of convection, the first coming this afternoon and evening with similar timing Monday. Currently convective debris from last night`s convection is exiting off the coast and a decent cumulus field is developing in its wake matching up well with convective inhibition has finally eroded from a 100mb Mixed Layer perspective. This trend should continue and showers and thunderstorms should begin in the next few hours. The GFS shows a smattering of convection this afternoon with a little more enhancement/organization around 00 UTC. The high resolution CAM guidance is showing a similar scenario albeit with more of a delay in timing. I have increased the pops slightly for the next six hours or so due to these trends. If and moreso when things get going, severe potential is fair game with strong winds and hail the primary threats. For the overnight hours beyond 03 UTC, things should be quiet persisting well into Monday morning. For Monday afternoon, residual Piedmont troughing and very similar thermal parameters will offer up more chances of convection. Guidance pops from the MAV aren`t as high as this afternoon and evening but may trend up in time which can be the nature in the warm season regarding convection. SPC has most of the area in a slight risk for Monday. Thermal profiles show temperatures should be a little warmer Monday afternoon as does the official forecast. Overnight lows tonight will remain mostly in the 70s with maybe an upper 60 or two well inland. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...With a boundary stalled over the area and some mid level energy still present Monday night may see a continuation of the afternoons` convective activity. This is especially suggesting by the 12Z WRF which shows a very agressive, possibly feedback-contaminated convective signal over mainly SC zones. Tuesday morning should offer a bit of a break in radar activity though not necessarily a rain-free period. With a little heating and the front still in the area Tuesday afternoon should once again see at least scattered coverage of thunderstorms. Coverage will wane to isolated or perhaps none at all later Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...GFS/ECMWF in agreement on the evolving H5 pattern in slowly migrating a broad but low amplitude trough eastward across the Great lakes and Ohio valley then into New England and SE Canada this period, while holding an upper ridge of varying amplitude over Florida and the Bahamas. This will allow a series of weak fronts and upper disturbances to move to our coasts, offering daily chances of thunderstorms. Late May/early June heating coupled with PWATS values between 1.50-1.80", and numerous surface boundaries, will support convection much of the extended forecast period. Next weekend potentially could turn wet, as enhancement of column moisture is drawn from the Gulf of Mexico by low pressure over Texas on Saturday, tracking to the Ohio Valley during Sunday. With the abundance of clouds, daytime temperatures will run near normal for the season, middle to upper 80s, but above average minimum temperatures in the upper 60s to low 70s. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... As of 01Z...The LBT and FLO terminals will likely see their convection early this evening, with activity east of the the 2 terminals by 01Z-02Z. The pseudo LEWP is making eastward progress and will affect the ILM-CRE-MYR terminals from 01Z-03Z. Strong to possibly severe tstrm wind gusts to occur across the coastal terminals. The inland terminals have seen their chance earlier for possible severe wind gusts. Any convection that affects them now may produce a strong wind gust. All terminals will see a brief reduction of horizontal vsby from heavy rain to 1sm-3sm, and possibly lower from a direct hit from one of those heavy rain producing shafts. Look for the main activity to finally push off the Carolina Coasts and into the Atl Waters between 03Z and 05Z. Residual convective debris clouds will prevail during the predawn Mon hrs and possibly up to a few hrs after daybreak Mon. Otherwise, expect a repeat of today for Sun with WSW to WNW 5 to 10 kt winds except becoming SSW-SW 10 to 15 kt along the immediate coast due to a pinned sea breeze. Convection will fire up across the inland terminals during the mid to late aftn and into the evening hrs and will indicate this with Prob groups. Extended Outlook...MVFR/IFR conditions are possible in thunderstorms Monday Night through Tuesday. More typical summertime scattered showers and thunderstorms are possible Wednesday and Thursday. && .MARINE... NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 830 PM Sunday...The majority of the convective activity will diminish-some with regard to their intensity, after it pushes thru the sea breeze and eventually off the NC and SC coasts. The rather deep and stable sfc based marine layer will act to squash the convection this time of the year. The convection should push offshore during the early pre-dawn Monday hours ie. between 1 and 3 am. Overall synoptic pattern will produce a SW wind initially, veering to the W during the predawn Mon hrs. Wind speeds around 15 kt. Significant seas will run 2 to 4 ft and primarily a function of 3 to 5 second period wind waves. No identifiable ground swell to speak of. Previous................................................. As of 300 PM Sunday...Bermuda High pressure will keep a southwest flow in place over the waters through the period. Speeds will be mostly in a range of 10-15 knots with the exception of a few hours this afternoon when stronger low level jetting warrants a few hours of 15- 20. Speeds will relax a little Monday. Significant seas will be 2-4 feet with the four footers mostly confined to the next few hours coinciding with the slightly stronger winds. SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Cold front should be stalled over land, keeping marine flow out of the SW. Solutions that push the front farther and lead to veered flow currently not favored though impossible to rule out. This boundary will tend to remain quite stationary through the period keeping a fairly light southwesterly flow across the waters. The proximity of the boundary paired with the poorly defined nature of the Atlantic high will keep wind waves minimal and preclude any swell energy for an overall wave forecast of just 2 ft. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...Near typical summer-like marine conditions this period as SW winds prevail with 2-3 foot seas. High pressure will remain centered just to the SE and E of Bermuda, and weak troughing inland should maintain SW wind flow Wed to Fri. The sea spectrum will be comprised of S-SSW waves 1-2 feet every 5 seconds and ESE waves 1-2 feet every 8 seconds. TSTMS will be active this period, moving generally from land to the coastal waters, and some may be strong from afternoon heating. Getting a radar update before heading out may be in the best interest of safely this period as we transition into a more active lightning and TSTM wind gust season. && .TIDES/COASTAL FLOODING... As of 930 PM Sunday...A coastal flood advisory has been issued for low lying areas bordering the Lower Cape Fear River from Wilmington southward. Latest tide guidance for the river gage located in the lower Cape Fear River in the vicinity of downtown Wilmington, has forecast levels reaching 5.85 ft MLLW at the 107 AM high tide early Monday Morning. Flooding along the lower Cape Fear from Wilmington southward begins at the 5.5 ft MLLW. Thresholds for shallow flooding will occur in a 3 hour window centered around high tide and for this occurrence, it will run from 1130 PM Sunday to 230 AM Monday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...Coastal Flood Advisory until 3 AM EDT Monday for NCZ107. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DCH/SHK SHORT TERM...MBB LONG TERM...MJC AVIATION...DCH MARINE... TIDES/COASTAL FLOODING...

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