Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 201842 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 242 PM EDT Thu Jul 20 2017 .SYNOPSIS... Showers and thunderstorms will be isolated in the days ahead, as an upper ridge builds from the west. The ridge will bring hot and humid conditions through the weekend. Rain chances will increase early next week as a surface trough deepens inland. && .NEAR TERM /THROUGH TONIGHT/... As of 3 PM Thursday...NVA and height rises associated by the retreating upper low working together with ambient subsidence associated with offshore convection to keep the much of the coastal plain not only rain-free but also hampering cu development. The area is shaping up for a muggy night with a continuation of light winds. Any patches of fog will only be of aviation concern as visibilities below 5SM do not appear in the cards. Tomorrow differs from today in that the aforementioned sources of downward vertical motion will be no more. With higher temps aloft and weak surface warm advection afternoon temps will soar into the mid 90s coast and upper 90s inland. There was some talk of a Heat Advisory but boundary layer hydrolapse rates seem to call for dewpoints that will fall during peak heating and preclude the 105F apparent temperatures needed across most of the area. This idea may be revisited by the evening and overnight crew however as the WRF in particular is less enamored with the idea. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 3 PM Thursday...Deep layer high pressure will dominate the conditions through the short term period. Mid level moisture will be lacking and most of the guidance is keeping the area dry through the period. Temperatures will be several degrees above normal most notably with Saturdays highs with upper 90s in the most northwest/inland zones. We will once again be on the cusp of a heat advisory depending on the dry air mixing down in the afternoon which may modify the apparent temperature just enough to preclude the 105 clip needed for three hours. Overnight lows remain steamy in the middle to upper 70s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 3 PM Thursday...Long term will be marked by gradually decreasing temperatures and increasing chances for precipitation as ridging at the surface and aloft breaks down and a cold front approaches and then moves across the eastern Carolinas. A consensus of guidance has the front stalling in our vicinity by late Tuesday or Wednesday, where it will linger into Thursday. Above normal temperatures Sunday and Monday will drop back down to or below climo for the remainder of the long term. Tuesday looks to be the best day for convection, with deep moisture in place in advance of the impending front. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 18Z...Light and variable winds in the very near term save for a more decidedly onshore flow at coastal terminals behind the seabreeze. Thunderstorms will be isolated and tend to stay west of the area through the period. VFR for most if not the entire TAF cycle as well. The exception may be pockets of MVFR over interior NC counties between ILM and LBT, possibly affecting the latter. Extended Outlook...VFR. Scattered showers and thunderstorms Monday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 3 PM Thursday...Winds have been light and somewhat variable today but a southwesterly direction will gradually come to dominate through the period. The reason being the pressure gradient-disturbing upper low will retrograde adequately for the Atlantic high to re-assert itself. Spectral plots show twin peaks of wave power at both 8 and 13-14 seconds, the latter being a ESE swell that will persist. As the wind picks up by up to a category the dominant period will shorten some but overall wave heights will not change significantly. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 3 PM Thursday...Bermuda High Pressure will keep southwest winds flowing across the coastal waters through the period. Some daytime increase in winds are expected with a decent sea breeze Saturday as it will be one of the warmest days of the year. Also the inland through will be enhanced by the heat which in turn will strengthen the low level jet overnight Saturday. Expect speeds to increase from the standard 10-15 knot range to 15-20 for a few hours. Significant seas will be 2-4 feet but a few five footers may develop overnight depending on just how much winds increase. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 3 PM Thursday...Circulation around high pressure over the western Atlantic will keep winds from the SW through the period. An approaching cold front may briefly tighten the gradient enough to warrant Exercise Caution headlines or a Small Craft Advisory late on Monday, but confidence on this is low at this time. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...99 NEAR TERM...MBB SHORT TERM...SHK LONG TERM...REK AVIATION...MBB MARINE...REK/MBB/SHK

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