Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 121935 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 335 PM EDT Wed Aug 12 2020 .SYNOPSIS... High pressure extending westward toward the Carolinas from the central Atlantic will maintain southerly winds along with seasonably warm and humid conditions. Weak trough of low pressure over the area will produce greater coverage of storms into the weekend, but will diminish into early next week as trough moves offshore late Sunday into Monday. && .NEAR TERM /THROUGH THURSDAY NIGHT/... Mid-level troughing to the west today will remain in place Thu, pumping an abundance of Gulf moisture over the region. Bermuda High and Piedmont trough will also contribute to broad southwest flow and enhanced low level moisture advection. Precipitable water around 2.1 inches today will rise to 2.3 to 2.4 inches later Thu and Thu night. Combine the deep moisture with CAPE in the neighborhood of 2500 J/kg, storm motion under 5 kt and a very deep warm cloud layer and the result will once again be storms capable of excessive rainfall. Coverage remains limited this afternoon and evening, but will increase on Thu. Weak trough in the vicinity today and Thu with hints of one, and possibly more, weak surface wave(s) developing along the trough Thu. The increase in low level convergence should help increase storm coverage Thu afternoon/evening. An increase in marine convection Thu night compared to tonight is also likely given the presence of the aforementioned surface wave(s). Increase in clouds and storms will keep highs near to slightly below climo. Lows will run several degrees above climo. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... A lingering trough will remain over the Carolinas as low pressure lifts north on Friday. At the same time, the mid to upper trough extending down just east of the Mississippi Valley will dig southward as it shifts eastward through Saturday. These two features along with localized boundaries including sea breeze and an abundance of moisture, will all contribute to a bit more widespread coverage of thunderstorms both Fri and Sat. Pcp water values will be over 2 inches. By Sat aftn the sfc boundary seems to lift more inland and north leaving a stiff SW flow. This should focus better coverage over NC, but upper trough will be aligned with the best shortwave energy running up from the SW to W right over our forecast area. May see convection running into the night as trough shifts slowly eastward. Overall, expect hot and humid weather to continue with more widespread clouds and convection Fri into the weekend and temps up around 90 during the day and 70s overnight. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Mid to upper trough continues to shift eastward with shortwave pushing a sfc front eastward and both reaching off the Southeast coast later on Sunday. Overall, expect winds to shift around to the W-NW and with limited coverage of tstorms Sun night into Mon in a more zonal flow aloft. Pcp water values up near 2 inches early Sun morning will be down near or less than 1.5 inches by late Sun through at least Mon. Dewpoint temps should drop several degrees Sun night into Mon. By midweek, the trough becomes more amplified again, as it digs down from the Great Lakes down to the Gulf coast. Shortwaves will rotate around up the upper trough through the Southeast allowing for greater coverage of storms once again Tues or Wed through midweek. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Some light to moderate convection this afternoon into early evening. Given the wind direction, most of the convection will be inland as the resultant pushes west. Some isolated fog after midnight, with some MVFR ceilings possible by daybreak. Extended Outlook...TSTMs, isolated to scattered will continue for the next 7 days. Patches of morning fog generally between 8z-11z should be expected, or localized MVFR stratus. Winds outside of TSTMs should remain light, and southerly. && .MARINE... Southerly flow continues into Thu before winds become more southwest as remains of weak surface trough push inland. Gradient tightens up a bit Thu with speeds increasing from 10 kt or less this afternoon and evening to 10 to 15 kt Thu and Thu night. Nocturnal convection is expected both tonight and Thu night, although coverage is likely to be higher Thu night. Seas run 2 to 3 ft through Thu and could bump to 2 to 4 ft Thu night. Southerly wind wave will continue to be dominant over a weak southeast swell. S-SW flow will continue Fri through the weekend. Enhanced troughing over NC will push winds up a bit Fri into the weekend, which in turn will kick seas up a bit. Overall, expect seas in the 2 to 4 ft range, but may see a few 5 fters in the outer waters, especially on Fri. Winds should veer around to the W-NW as a weak front/trough moves through the waters from west to east late Sun into Mon morning. Expect increased coverage of thunderstorms this weekend. Coverage should decrease slightly by early next week after front/trough moves through. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...ILM NEAR TERM...III SHORT TERM...RGZ LONG TERM...RGZ AVIATION...III/43 MARINE...III/RGZ

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