Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 161902 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 302 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 250 PM Wednesday... The early afternoon surface analysis shows a surface trough extending northeast to southwest along the NC coast and then laying across central SC and GA. A cold front extended from near Washington DC westward to the Ohio river valley. The air mass across northern portions of the area has dried out a bit with dew points in the upper 60s to lower 70s near the VA border while it remained very humid across the Sandhills and southern Coastal Plain with dew points in the mid to upper 70s (dew point was 79 at KGSB at 18Z). GOES-16 satellite imagery shows a growing cumulus field in an arc from the Triad south across the western Piedmont and Yadkin valley into the Sandhills. Doppler radar is showing a couple of isolated showers in the northwest and southern Piedmont an in a region of enhanced instability and convergence. Convection allowing models are consistent in highlighting the western and southern periphery of the RAH CWA for isolated to widely scattered showers and thunderstorms this afternoon and evening with little to no convection from Raleigh northeast. The convection will drift slowly southeast and should wane by mid evening with little to no convection overnight. Another period of late night and early morning fog and stratus is expected to develop across the northern and central Coastal Plain and the northeast Piedmont. Lows tonight will range in the lower to mid 70s. -Blaes
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
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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
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 AM Wednesday... Friday and Friday night: An upper level shortwave trough and surface cold front will approach the region from the west on Friday, though it will likely get hung up over the mountains. As a result, strong southwesterly flow over Central NC will result in warm, humid conditions and the best chances for convection will be along differential heating boundaries near the foothills and along the sea breeze. For now, Friday night appears to be largely dry, although if enough pre-frontal moisture makes its way into Central NC, some convection could persist into the night. Highs in the upper 80s to mid 90s and lows in the low to mid 70s expected. Saturday and Sunday: A stronger upper level trough and surface cold front will approach from the west on Saturday, with the upper level trough swinging through the region and deamplifying as it does so Saturday night into Sunday. Although the front appears quite strong, it is expected to stall over Central NC, having a hard time progressing through the area before getting washed out Sunday night. Best chances for convection will be in proximity to the stalled front, lower in its wake, Saturday and Saturday night. Chances for convection could decrease further on Sunday, again with the highest chances farther southeast. Southerly to southwesterly flow at the surface will be enhanced ahead of the front with return flow around the Bermuda High extending into the region. Highs will generally remain in the upper 80s to low 90s over the weekend (although if the front progresses into the region a bit further it will affect temps to the northwest). Lows generally in the low to mid 70s. Monday onward: Surface high pressure will build off the Mid-Atlantic coast, with continued southerly flow over Central NC through mid- week. Aloft, high pressure will build over the Southeast U.S. with a trough amplifying over the Midwest Tuesday and progressing east- southeastward. With the little change in airmass expected, continued diurnal convection in the favored areas will be most likely. As for temperatures, expect highs generally in the mid 80s North to low 90s South and lows in the upper 60s to mid 70s. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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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
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...BLAES LONG TERM...KCP AVIATION...BLAES

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