Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 260013 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 813 PM EDT THU AUG 25 2016 .SYNOPSIS... High pressure will extend across the region through Saturday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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As of 810 PM Thursday... Latest mesoanalysis shows that nocturnal stabilization has begun with mixed layer CAPE values decreasing. They are now below 1000 J/kg across the Triad where earlier this afternoon they exceeded 2000 J/KG. Last few images from the visible satellite spectrum showed largely diurnally forced cumulus dissipating. Isolated convection across the mountains, Foothills and western Piedmont areas including the Yadkin Valley and western Triad areas has almost completely dissipated with just a lone shower across Caldwell and another across Henderson Counties. This trend should continue with fair weather expected across the RAH CWA. Recent gridded database update included the removal of all PoPs from the forecast, improvements to sky conditions as cumulus fades away and some minor adjustments to hourly temperatures and dew points. Previous discussion... Expect clear-partly cloudy skies later this evening into the overnight hours. Could see pockets of fog across the region though most places will have unlimited visibility. Overnight temps will be a couple of degrees warmer, owing to a modifying air mass. Min temps in the upper 60s to around 70.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... As of 320 PM Thursday... Mid/upper level anti-cyclone currently positioned over the Deep South relocates over our region on Friday. Subsidence associated with this feature will limit cloud production, as well as inhibit convective initiation. The subsidence warming will lead to afternoon temps several degrees above normal for this time of year. High temps in the low-mid 90s will be common. While sfc dewpoints will creep back up to around 70, heat index values do not get too ridiculous, averaging within a degree or two of 100 degrees. The exception may be the sandhills. If temps reach the upper 90s, heat index values will approach 105 degrees. While the low level air mass will be more than adequately unstable to support isolated/scattered convection, mid level subsidence inversion should inhibit development. It should feel noticeably more muggy Friday night with dewpoints in the lower 70s. Overnight temps in the low-mid 70s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 235 PM Thursday... Saturday through Sunday night: The weekend is setting up to be mostly dry as an upper level ridge sits directly on top of central NC. At the surface a high pressure system will start Saturday over the Great Lakes before progressing to the northeast through New England and the Canadian Maritimes. Models try to generate a few showers, particularly on Saturday afternoon across the western portion of the CWA. Will put slight chance in the forecast but confidence on this actually occurring is fairly low given the strong subsidence overhead. Saturday will be hot with maximum temperatures in the mid 90s but dewpoints should stay in the low 70s. This will result in heat indices creeping into the 100-105 degree range but probably wont be enough for a heat advisory. Temperatures will drop back to near 90 degrees on Sunday afternoon. Monday through Thursday: Model solutions begin diverging early next week so details will be hard to pin down at this point but we do know that the upper level ridge should relax and upper flow will become more zonal north of the area. To the south, the pattern will largely be dictated by where the current tropical invest winds up. Forecast model track spread is very large at this point as is the intensity guidance. Have increased chances for precipitation into the chance range for the end of the forecast period to account for any possible effects of the tropical system. Once the ridge breaks down the storm will be allowed to recurve the question is how far west will it be by that time and how quickly will it recurve. If the storm recurves before reaching the Florida Peninsula we could see dry weather here in NC as the storm goes out to sea. However if the storm recurves in the Gulf further west, then we could see rainfall ahead of the storm as early as Thursday morning. Highs near 90 each day with lows in the lower 70s. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 755 PM Thursday... 24 hour TAF period: High pressure will continue to extend across the area through the 24 hour TAF period, resulting in generally dry and VFR conditions with light and variable winds. The one possible exception may be around daybreak when some MVFR/IFR visbys may develop at the eastern TAF sites, primary KRWI and KFAY (with KRWI standing the best chance). Outlook: This area of high pressure is expected to maintain its influence over our region through early next week. This suggest an extended period of VFR conditions, aside from patchy early morning MVFR/IFR fog and possibly some isolated convection from this weekend onward. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...Blaes/WSS SHORT TERM...WSS LONG TERM...RE AVIATION...BD/WSS

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