Area Forecast Discussion
Issued by NWS Wilmington, NC

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818 FXUS62 KILM 200444 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1244 AM EDT Fri Oct 20 2017 .SYNOPSIS... Mostly clear skies and seasonably warm temperatures are expected into the weekend, as a dry upper ridge builds across the region. An approaching strong cold front will bring showers and thunderstorms early next week. Much cooler temperatures are forecast in the wake of the front beginning Wednesday. && .NEAR TERM /THROUGH FRIDAY/... As of 900 PM Thursday...High pressure consolidating over eastern TN will gradually shift east-northeast Fri as it slowly weakens. A weak shortwave has exited the coast and is being replaced by a mid-level ridge through Friday. Winds will be light and variable through the period due to a very weak gradient in place. Deep dry air and light to calm winds overnight will lead to strong radiational cooling with inland cold spots dipping to the mid 40s. Along the coast, lows will be in the lower to mid 50s. Very dry air lingers in the region Fri with precipitable water values peaking around 0.50 inch in the afternoon. Highs on Fri will end up a few degrees warmer than today, mainly due to building heights/thickness and further air mass modification. Flow remains northerly through just about the entire column so there is no real warm advection to speak of. Relaxed gradient will allow for development of weak afternoon sea breeze which may temper highs along the coast, but do not expect any cloud development. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Mid to upper ridge up the southeast coast and surface high pressure to our north will both shift east through the period. Overall a very light NE flow will veer around becoming more easterly through the period. This will allow for an increase in low level moisture basically late Sat into Sat night. This should bring some low clouds mainly over northeast SC or some fog elsewhere, mainly near the coast. Dewpoint temps will increase from near 50 to 55 Fri night to 55 to around 60 by daybreak Sun. The strong subsidence inversion will slowly erode through the period but not enough to allow for any pcp or for that matter much in the way of cloud. The dry air in place will allow for a large diurnal swing, but slightly dampened Sat night with an increase low level moisture. Overall mainly clear skies and very light winds leading to decent radiational cooling. Overnight lows will be 50 to 55 Fri night and 55 to 60 Sat night most places while bright Oct sunshine will bring temps up close to 80 Sat aftn. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...the upper level pattern continues to show high pressure breaking down and a large scale trough moving to the eastern half of the United States by Tuesday. This is slower than the previous run. At the surface the frontal boundary is slower with the GFS bringing the frontal boundary into the area Tuesday night. The ECMWF is even slower with the boundary pushing off the coast Wednesday morning. Precipiation chances start late Sunday night with isolated showers then chances increase to likely on Tuesday with the frontal passage. High temperatures will be around 80 degrees on Sunday and Monday but with the frontal passage will see temperatures falling into the upper 60s to middle 60s by Wednesday and Thursday. Lows on Sunday night will be in the lower to middle 60s but will fall into the middle to upper 40s by Wednesday night. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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As of 06Z...Given the low dewpoint depressions, calm wind and clear skies, have included a tempo group for MVFR fog at all the TAF sites, mainly in the 08-12z time frame. However, at KCRE, will forecast prevailing MVFR fog through 12z with tempo IFR fog/stratus. After 12z, skies will be SKC with light N winds, becoming E to SE less than 10 kt at the coast after 17-19z due to a developing seabreeze. KLBT has not reported an observation in the last few hours and will append AMD NOT SKED to the TAF with the 06z issuance. Extended Outlook...Showers and thunderstorms may result in flight restrictions Mon-Tue.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1000 PM Thursday...High pressure over eastern TN will shift east-northeast Fri. Gradient over the waters continues to relax with speeds under 10 kt overnight. Flow remains north to northeast through the period, and gradient remains weak with speeds 10 kt or less Fri. Winds may veer to east or even southeast later in the day in response to development of weak sea breeze. Seas will be 2 to 4 ft overnight and 2 to 3 ft on Fri with an easterly swell around 9 seconds slowly decaying. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...High pressure to our north will shift east through the period. Overall a very light NE flow will veer around becoming more easterly through the period, remaining less than 15 kts. Expect a slight chop Sat aftn as winds spike up and become more on shore, but overall benign seas expected mainly around 3 ft or less. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Thursday...High pressure over the waters will weaken and shift offshore. This will allow for veering of the winds with a southerly wind by Monday. Seas will be 2 to 3 feet on Sunday and will slowly increase by late Monday to 3 to 4 feet as the winds slowly increase ahead of front that will approach the waters late Tuesday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RJD/III SHORT TERM...RGZ LONG TERM...DRH AVIATION...RJD is the U.S. government's official web portal to all federal, state and local government web resources and services.