Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 170210 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1010 PM EDT Wed Aug 16 2017 .SYNOPSIS... Summertime heat and humidity will continue across the area through Friday with widely scattered showers and thunderstorms. Convection coverage will increase during the weekend into early next week as a cold front approaches from the northwest late Friday and stalls just inland from the coast thru the weekend and continuing into early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 1000 PM Wednesday...Updated to include POPs late this evening and into the pre-dawn Thu hrs. The dynamics, ie. PVA, associated with the mid- level vort across north central NC, continues to ignite isolated convection which has now bled into the ILM CWA, west of the I-95 Corridor ie. Marlboro and Darlington Counties. Dillon and Robeson Counties will be next as this mid-level vort pushes eastward thru 1 am Thu. There-after, kept pops below 15 percent. Previous.................................................. As of 845 PM Wednesday...Majority of the convection across the ILM CWA is weakening and dissipating given the loss of the days insolation. Plenty of interacting sfc boundaries that helped with the forcing portion of enabling convection to occur. However, with the loss of heating, so goes the fuel or CAPE to sustain these storms. However, there is a weak mid-level s/w trof progged to push eastward across north central NC this evening and overnight that could develop a few storms that may come close to the ILM CWA. For now, will mention it here in this discussion but hold off from raising overnight POPs. Have basically tweaked overnite hrly temps and dewpts upwards to account for latest trends and what 18Z progs indicated for the overnight period. Could see winds decouple late this evening and overnight and could give rise to possible ground fog especially locations that receive rainfall from today`s convection. Previous................................................... As of 300 PM Wednesday...With dewpoints in the mid 70`s and temperatures in the upper 80`s to low 90`s, heat indices have reached at or just above 100 degrees across much of the area already. The Heat Advisory will remain in effect through this afternoon for portions of the area. Latest visible satellite illustrates quite the healthy cu field across the area, while latest radar imagery only shows a few showers and thunderstorms which have developed outside of the forecast area. With latest guidance, do continue to expect isolated to scattered showers and thunderstorms to develop this afternoon into the early evening hours with the assistance of the the afternoon sea breeze and piedmont trough. Any convection that does develop will dissipate later tonight , with conditions remaining fairly quiet overnight with overnight low temperatures in the mid 70`s. Patchy areas of fog are possible towards the morning hours. On Thursday, upper level ridging will move into the Carolinas ahead of the approaching cold front which is progged for later this week. However, even with ridging in place, some available moisture, low level convergence and lingering boundaries, have kept in slight chance/chance pops for isolated to scattered convection. The heat will be of discussion again as well, as higher dewpoints combined with temperatures in the each aftn and evening thru the weekend. low to mid 90`s will likely allow heat indices to reach 100 degrees, with some locations reaching advisory criteria. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...High pressure will give way Thursday night as a Piedmont trough develops over the Carolina`s on Friday ahead of a cold front that will move into the central Carolinas by early Saturday morning. The deep 2+ inch precipitable water will continues its hold over the area through this period. Convection is expected on Friday and Friday night with the established trough and the approaching cold front. With the 850 millibar temperatures hitting the 19 to 20C range expect another hot day with possible heat advisories for portions of the forecast area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...Cold front stalled either just to our west or even over western counties on Saturday while moderately strong trough crosses through the Northeast and MidAtlantic. Thunderstorm coverage should be elevated above the norm. Thunderstorm coverage may also not show the normal diurnal decrease due to the presence of the boundary. The higher concentration of storms will be over northern zones where there also may be a small severe weather threat. Temperatures will be running close to normal. The boundary will show little movement into Sunday but height rises aloft will be underway. Overall expect a downward trend in storm coverage and a warmer afternoon. Attention to Monday`s forecast continues to increase each day due to the solar eclipse. Unfortunately there isn`t much different in the way of thinking and even less fortunate the news isn`t great. True the front will be weakening but convective signals in the models are still suggesting ample moisture for considerable coverage of thunderstorms that afternoon. The silver lining could be the rising heights aloft, possibly capping thunderstorm formation until after the eclipse or at least its peak. Even so all it takes is one vigorous towering cumulus to ruin the view over a given location. By Tuesday the front no longer appears in the models but a well defined piedmont trough develops. Thunderstorms forming within this boundary and moving east paired with seabreeze activity calls for scattered POPs just about area-wide. By Wednesday some mid level troughiness starts breaking into the area in association with a large trough forming north of the Great Lakes. A continued moist boundary layer paired with energetic NW flow likely means a continuation of the unsettled weather. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... As of 00Z...Weakening isolated showers and thunderstorms will continue thru 02Z and could provide brief MVFR/IFR conditions with a direct hit. Otherwise, after 02Z, look for convection to dissipate. Have indicated MVFR fog conditions mainly after 06Z thru 12Z. Any terminals that experience pcpn, could see fog conditions drop vsby to IFR thresholds. Winds this evening, mainly variable, will become calm across the inland terminals and possibly the coastal terminals as well. The fog and sct low stratus will dissipate by 13-14z with diurnal cu quick to develop. Once again, will have a sea breeze and the piedmont trof provide forcing for convection to develop from. There- after, outflow boundaries will interact with one another as well as the sea breeze and piedmont trof...keeping convection development going from 17Z thru 24Z. Winds generally SE-S during Thu at 5 to 10 kt speeds except 10 to possibly 15 kt along the coastal terminals if the sea breeze is able to fully develop. Extended Outlook...A brief period of MVFR/IFR conditions can not be ruled out in isolated to scattered showers and thunderstorms Thu and Fri aftn and evening. A better chance for flight restrictions due to showers and thunderstorms will occur on Sat and Sun. Low stratus and some fog during the overnight and early morning hours may result in flight restrictions as well each day. && .MARINE... NEAR TERM /TONIGHT THROUGH THURSDAY/... As of 845 PM Wednesday...Outflow from convection over the mainland will temporarily push across portions of the local waters and temporarily disrupt the weak synoptic flow. Overall, wind speeds will run 5 to 10 kt and that may even be too high. Wind directions will be a challenge until the outflows dissipate and/or get absorbed in the overall weak synoptic flow. Significant seas will run around 2 ft and primarily be a function of a 1 to 2 foot ESE ground swell at 7 to 8 second periods. Previous.................................................... As of 300 PM Wednesday...Conditions will remain fairly quiet across the waters as Hurricane Gert continues to move well away from the waters, off to the northeast. Southwest winds up to 10 kts tonight will veer to the north and then northeast Thursday morning, and back to the southeast by the afternoon hours. Winds will remain around 5 to 10 kts. Seas will be around 2 to 3 ft. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Winds will be from the south and will veer to the southwest of Friday and Friday night ahead of a cold front that will stall inland. This will increase the winds from around 10 knots to 15 knots late Friday. Seas will respond by increasing from around 2 to 3 feet to 3 to 4 feet late Friday night. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Wednesday...A front will be stalled over land over the weekend and into Monday in a weakening state. This boundary will serve a similar function to the piedmont trough normally seen during the warm season and we should still see a fairly typical southwesterly flow. Seas will run 2 to 4 ft for the most part, highest offshore in the coast-parallel flow. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DRH NEAR TERM...DCH/SGL SHORT TERM...DRH LONG TERM...MBB AVIATION...DCH is the U.S. government's official web portal to all federal, state and local government web resources and services.