Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 162326 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 726 PM EDT Sat Sep 16 2017 .SYNOPSIS... Weak high pressure will continue to cover the eastern United States through next week. Hurricane Jose will lift north, expected to move between the North Carolina coast and Bermuda Sunday and Monday. This will produce an increased rip current risk into early next week. Temperatures should warm well above normal by next Wednesday. && .NEAR TERM /THROUGH SUNDAY/...
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As of 700 PM Saturday...Convergence along the seabreeze boundary coupled with shallow instability earlier generated showers in a broken line from just south of Lake Waccamaw to near Conway to just inland of Georgetown, SC. These showers were struggling to break through a subsidence inversion up around 700 mb as shown by radar-measured echo tops which were struggling to pop to 15-18kft at best. A cooling boundary layer should allow any lingering showers to die within the next hour, although convective clouds spreading out along the base of the subsidence inversion may linger through midnight before thinning out. No other significant changes were needed to the forecast. Discussion from 300 PM follows... Hurricane Jose will make its closest approach to our area late tonight and Sunday as it moves N, its center remaining several hundred miles off the coast. The risk from Jose is confined offshore and to the beaches. The beaches are expected to experience frequent and strong rip currents through Sun. Also, the surf will be rough with steep breakers, the result of long period swell. Often times, as these tropical systems bypass the area to the E, the western side is the drier side. Since Jose will continue to undergo considerable W to NW shear, this will not be an exception. A stray shower can not be ruled out as the heating dissipates late afternoon, but we will keep POPs below threshold. We do expect Jose to expand as it travels N and this should allow its cloud canopy to scrape at least most coastal locations. It is possible, especially with heating on Sun that we begin to see isolated to scattered showers develop, particularly along the resultant seabreeze. We will keep slight chance/chance POPs in the forecast for most of Sun, highest during the afternoon as the guidance has not changed significantly and suggests some moisture moving around the back side of Jose and skirting our coast in increasing northeasterly flow. NNE to NE winds will be highest at the beaches, up to 15 to 25 mph in gusts on Sun. Lows tonight will be in the mid and upper 60s to around 70 at the beaches. Highs will be in the lower to mid 80s on Sunday.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 245 PM Saturday...Rather quiet weather for the short term period. Guidance has backed off a bit on any lingering showers associated with the outermost bands from Jose, at least for overnight Sunday. For Monday into Tuesday morning weak high pressure will build in both at the mid levels and at the surface. No real issues or changes with the temperature forecast. I did tweak highs for MOnday up a little based on the latest guidance. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 245 PM Saturday...Hurricane Jose will be exiting to the north Tue and leaving weak high pressure as the most significant surface feature during the period. The center of the high will become elongated as it shifts from northwest of the area Tue to the northeast for the weekend. The weather for the period will depend more on the mid-level pattern as opposed to surface features. Lingering mid level moisture late next week in conjunction with a shortwave dropping southeast after topping weak 5h ridge to the west may be sufficient for development of diurnal convection Thu and Fri. Late in the period drier air aloft spreads over the region as the ridge expands east. Confidence in this solution is not high and so the inherited silent pop for Thu and Fri will be maintained. High temperatures a couple degrees above climo early in the period will trend toward climo late next week while low temperatures remain above climo through the period. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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As of 00Z...Daytime cumulus clouds spread out into a deck around 9000-12000 feet AGL this evening, and these mid-level clouds may linger through this evening across eastern South Carolina. VFR conditions and light northeasterly winds should continue through the night. A layer of low stratus below 1000 feet AGL is expected to develop across eastern NC and move into the ILM area around daybreak, or 11Z. This is about the same time that showers developing over the Gulf Stream also move westward into the ILM vicinity. The net result could be several hours of IFR or low MVFR conditions at ILM between 11-16Z Sunday. Probabilities of this weather making back into the MYR/CRE area is lower, but still worth mentioning in the forecast. VFR conditions should continue through Sunday inland. Extended Outlook...MVFR ceilings may persist at the coastal terminals, mainly ILM, Sun night and possibly into Mon. Any showers and short-lived visibility restrictions will be confined to the coast as well as tropical cyclone Jose makes its closest approach, but its center remains several hundred miles offshore as it moves N.
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&& .MARINE...
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NEAR TERM /THROUGH SUNDAY/... As of 700 PM Saturday...NDBC and local CORMP buoys are reporting seas 1 to 1.5 feet higher than was previously forecast. The only significant change to the forecast was to update forecast sea heights through the night. Even with this adjustment upward, the coastal waters near Myrtle Beach and North Myrtle Beach may not actually see 6 foot seas develop until after daybreak Sunday. Rather than create confusion by canceling and then reissuing the Small Craft Advisory for that one forecast segment,I`ll just leave it in place despite the delay in hazardous conditions materializing. Discussion from 300 PM follows... A Small Craft Advisory for Hazardous Seas remains in effect. The highest of the seas are expected Sun and Sun night. The center of Hurricane Jose will move N, passing several hundred miles to the E of the Cape Fear coast. Swell energy generated by this tropical cyclone will allow seas to build, reaching 5 to 7 ft this eve and 6 to 9 ft Sun morning. The swell period will be 12 to 14 seconds. Long period swell will cause inlet turbulence during the outgoing tidal flows, and breaking of larger than normal waves near shallow areas and sand bars. The wind direction will be NNE to NE through the period. Wind speeds will increase to 15 to 20 kt late tonight and remain in that range on Sun. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 245 PM Saturday...Some steady albeit modest northeasterly winds will persist for several hours across the coastal waters Sunday evening into Monday morning. Speeds will be 10-15 knots and probably leaning toward the higher side of the range. Expect a gradual weakening of the winds later Monday into early Tuesday with speeds dropping to ten knots or below. Significant seas will remain on the higher side especially Sunday night with 5-10 feet. Expect a slow dropoff Monday through Tuesday morning with heights of 4-7 feet by the end of the period. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 245 PM Saturday...Waters will be between high pressure to the west and exiting Hurricane Jose to the northeast. This will result in offshore flow at the start of the period. Gradient will be such that speeds will be under 15 kt Tue, dropping under 10 kt Tue night and remaining 10 kt or less through the end of the period. Surface high will shift east, passing north of the waters Wed and leading to the development of southerly flow. Long period swells from Jose will linger through the period. Swell will be combined with wind wave to produce seas right around SCA thresholds early in the period. Both swell and wind wave will gradually decrease through the period. Seas will drop from 4 to 6 ft Tue morning to 2 to 4 ft Tue night and 1 to 3 ft Wed and Thu.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...High Rip Current Risk from Sunday morning through Sunday evening for SCZ054-056. NC...High Rip Current Risk from Sunday morning through Sunday evening for NCZ106-108-110. High Rip Current Risk until 8 PM EDT this evening for NCZ106- 108-110. MARINE...Small Craft Advisory for hazardous seas until 8 PM EDT Monday for AMZ250-252-254-256.
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&& $$ SYNOPSIS...SHK NEAR TERM...RJD/TRA SHORT TERM...SHK LONG TERM...III AVIATION...TRA

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