Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 261944 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 344 PM EDT FRI AUG 26 2016 .SYNOPSIS... Warm and humid conditions will continue through the weekend. The chance of showers will increase in time as well. Moisture from the tropics may move across the area next week before a strong cold front moves across the region later in the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 330 PM Friday...WV imagery paints the picture this aftn with clearly drier air elongated along the east coast in response to surface high pressure and an amplifying ridge aloft. A few showers have developed well west of the CWA where moisture return is better and dew points are higher, but these are expected to be short lived and no convection is forecast within the CWA. While it is quite hot and humid with heat index values around 100, suggesting a very unstable atmosphere, temperatures aloft are warming and subsidence beneath the strengthening ridge is drying the column as well. These two factors are squelching any strong updrafts, and therefore no showers or tstms are forecast through tonight. This upper ridge will strengthen tonight as the surface high deflects slowly to the northeast. This allows column flow to become predominantly E/NE as opposed to more northerly, and this will advect more moisture into the area tonight. While no showers are forecast, some stratocu may advect onshore late. No fog is forecast despite the increasing moisture as mins in the low 70s remain above crossover values, and an easterly LLJ increases to 20-25 kts. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... As of 330 PM Friday...Large ridge of high pressure aloft will expand and push to the north through the weekend. As this occurs, surface high pressure will drift NE away from the area, but maintain a ridge axis down into the Carolinas. On Saturday, this will lead to another above normal day with ample sunshine driving temps into the low 90s away from the immediate coast. Better moisture return on deepening easterly flow in response to the ridge shifting north may allow for some isolated showers/tstms on Saturday, but very dry air above 850mb will persist and will cap pop at SCHC, focused across inland zones. An interesting event happens Sunday. A vorticity impulse from the Atlantic, possibly the residual vorticity from what was once Tropical Storm Fiona, advects west beneath the mid-level ridge and into the Carolinas. While there appears to be no surface reflection beneath this feature, the increased PWAT combined with subtle height falls and PVA should create increasing coverage of showers/tstms on Sunday. Guidance is not aggressive in its POP, but soundings depict increasing instability and column saturation. Inherited forecast has SCHC for Sunday, but will ramp this up to mid-CHC for the potential for scattered activity Sunday. More widespread clouds and convection will keeps temps a bit cooler on Sunday, with highs in the upper 80s to around 90. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 330 PM Friday...Overall there remains uncertainty with the extended as the ECMWF and GFS want to handle the tropical moisture plume from AL99 much differently. The former keeps the plume over the east coast Monday and Tuesday while the latest GFS keeps the moisture and system more in the Gulf of Mexico. I did keep the overall theme of the forecast intact which leans toward the drier solution and keeps pops somewhat muted. All guidance shows a decent mid level trough pushing moisture offshore later in the week with another decent cold frontal package. No changes to the temperature forecast which hovers just above climatology throughout. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... As of 18Z...VFR expected for at least the next 12 hours, with MVFR conditions possible in the early morning hours due to patchy fog and haze. No weather is expected. Winds for the inland terminals will be light and variable this afternoon with high pressure directly overhead. The coastal terminals will see S to SE winds into the evening hours as a moderate sea breeze circulation develops. Expect scattered cu with bases around 5 kft, especially for the inland terminals, this afternoon. Cloud cover will fade overnight. EXTENDED OUTLOOK...Potential for sub VFR due to areas of haze or fog early each morning and with isolated convection from Sunday through Tuesday. Otherwise VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 330 PM Friday...High pressure slowly moving off to the northeast will maintain a ridge axis down into the southeast coast, dominating the synoptic flow across area waters. This will keep wind speeds light thanks to a weak gradient, but the predominant direction will gradually shift from E/NE to SE tonight but with speeds remaining at 10 kts or less. These light winds will allow the ongoing 2-3 ft/7sec SE swell to remain the predominant wave group, driving seas of 2-3 ft through tonight. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 PM Friday...Broad high pressure centered well off the New England coast will ridge subtly down into the Southeast through the weekend. This will maintain a weak pressure gradient driving winds from the E/NE at speeds around 10 kts both Saturday and Sunday. These light winds will ensure the longer period swell remains the dominant wave group, and this swell is progged to amplify beginning Sunday with some 14-15 sec wave energy entering the spectrum. The majority of this wave energy will show up beyond the short term, into next week, but the continued SE swell becoming 3ft/10sec will push wave heights from 2-3 ft Saturday, to 3-4 ft on Sunday. LONG TERM/MONDAY THROUGH WEDNESDAY/... As of 330 PM Friday...Expect east to northeast winds Monday and Tuesday as broad troughing develops off the southeast coast and weak high pressure remains centered across the midwest and the Appalachians mountains. Speeds will be 10-15 knots and mostly near the lower end of the range. By Wednesday more of a southwest flow develops ahead of a cold front moving in from the northwest. Seas will finally have a little assist from distant tropical entities but nothing overly dramatic, as significant seas will be 2-4 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...SHK NEAR TERM...JDW SHORT TERM...JDW LONG TERM...SHK AVIATION...REK MARINE...JDW/SHK is the U.S. government's official web portal to all federal, state and local government web resources and services.