Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 162235 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 635 PM EDT Wed Aug 16 2017 .SYNOPSIS... A surface trough will extend along the North Carolina coast southwestward into central South Carolina and Georgia through Thursday. A back door cold front will approach the region on Thursday before another cold front approaches from the northwest on Friday and moves into the region on Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 635 PM Wednesday... Main adjustment to the near term forecast was to update dewpoints across central NC which currently vary from the mid-upper 60s across the northeast Piedmont to the mid-upper 70s across the western Piedmont and Sandhills. A slight-moderately unstable air mass covers the region with the greatest instability in an arc stretching from the western Piedmont into the Sandhills. Within this arc, a few showers and isolated storms were occurring. These showers/storms were mainly driven by afternoon heating, so most of the convection will dissipate with loss of heating, around 00Z. A weakening perturbation aloft will trigger/sustain an isolated shower/storm into the evening hours, mainly west-south of Raleigh. Overnight, areas of low clouds and fog appear highly probable over the coastal plain, Sandhills, and potentially the eastern Piedmont. Min temps in the low-mid 70s.
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 300 PM Wednesday... A short wave ridge axis over the Carolinas on Thursday morning will give way to decreasing heights and an increasing southwesterly flow on Thursday night. An increasing southerly flow will develop allowing a recovery of moisture with precipitable water values climbing back to between 2.0 to 2.25 inches by Thursday evening. While the forcing for ascent is modest, the return of warm advection and increasing moisture should result in an uptick in showers and thunderstorms over today. After a period of morning stratus in the Coastal Plain and northeast Piedmont, expect variably cloudy skies. Low-level thickness values increase a few meters supporting highs between 89 to 94 with lows in the lower to mid 70s. -Blaes && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 335 PM Wednesday... The cold front that`s currently moving across the Central Plains is progged to move across the Appalachians early Friday and across central NC late Friday or Friday evening. This feature and its assoc upper short wave trough will provide the support for scattered showers/tstms Friday and Friday evening. Like fronts often do this time of year when the upper trough pulls out, Friday night`s front will slow down and stall across eastern NC overnight into Saturday morning, and prolong the chance for scattered showers/tstms from about I-95 eastward. Locations west of Raleigh to the Triad should remain dry most of the daytime Saturday. Then another short wave trough and it`s cold front will move across the Mid Atlantic and Carolinas Saturday night into Sunday morning, thus additional wdly sct showers are possible during that time. Given the fast flow to our north, the short wave will exit to our northeast while leaving the sfc cold front stalled across the Carolinas late Sunday into Monday morning, before the front dissipates later Monday. Unfortunately, this may set the stage additional showers on Monday, and with a fair amount of cloudiness around, possibly obscuring the partial eclipse Monday afternoon. I wouldn`t give up hope just yet for seeing the partial eclipse here in central NC, as there is a fair amount of disagreement among models regarding how far south the front will stall, and thus where the best chance for clouds and showers will be. Stay tuned! At or above-climo rain chances will continue Tue and Wed thanks to cyclonic flow and a series of short waves crossing the region. Temps during the long term period at or above normal. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... As of 235 PM Wednesday... The 24 hour TAF period...widespread VFR conditions early this afternoon will give way to isolated to widely scattered showers and storms with local restrictions across the western and southern portions of the RAH CWA. SCT-BKN cumulus has developed and expanded in an arc from the Triad south across the western Piedmont and Yadkin valley into the Sandhills in a region of enhanced instability and convergence. Expect isolated to scattered showers and thunderstorms to develop in this region during the mid afternoon hours and continue into the early evening before dissipating during the mid to late evening. The greatest chances of convection will be at the KINT and KGSO terminals with a small threat of a shower at the KFAY terminal and no precipitation expected at KRDU and KRWI. Another round of late night stratus and fog is expected to develop overnight, primarily across the Coastal Plain and the northeast Piedmont/Sandhills. IFR restrictions are likely to develop in most locations by the predawn hours with a period of LIFR conditions in fog and stratus possible across the northern Coastal Plain at KRWI. Local restrictions will improve during the mid morning hours on Thursday before scattered showers and storms redevelop toward early afternoon. Looking further ahead...A cold front will approach the region on Thursday into Friday and then settle across the area on Sunday into Monday. This result in an increase shower and thunderstorms, primarily during the afternoon and evening on Thursday into Saturday with a decrease in adverse aviation conditions on Sunday into Monday. -Blaes && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BLAES NEAR TERM...WSS SHORT TERM...BLAES LONG TERM...np AVIATION...BLAES

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