471 FXUS62 KGSP 092339 AFDGSPArea Forecast Discussion National Weather Service Greenville-Spartanburg SC 739 PM EDT Tue Sep 9 2025
.SYNOPSIS... Dry high pressure will persist over the region through this weekend. We will have a gradual warming trend into early next week as an upper trough moves off the East Coast and an upper ridge moves in from the west. Dry weather will continue into the weekend.
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.NEAR TERM /THROUGH WEDNESDAY/... As of 736 PM Tuesday: No changes. Fair weather continues. Scattered remaining stratocu over the mtns should dissipate with sunset. Cirrus to the east will translate further east thru midnight. Temp trend looks good, but dewpoints were adjusted in some locations.
Otherwise...broad upper troughing will continue to envelop the eastern CONUS east of the Mississippi River through tomorrow. At the surface, a massive sprawling high remains draped from eastern Canada down the east coast and Appalachians with dry northeast flow will prevailing and PWATs well below an inch. This will keep dry and benign weather in place with temperatures below seasonal averages. Overnight lows tonight are expected to fall into the upper 40s to mid 50s with a warming trend beginning tomorrow as afternoon highs rebound into the upper 70s to low 80s. Otherwise, a few instances of mountain valley fog will be possible, especially across the Little Tennessee Valley.
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.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 1256 PM EDT Tuesday: An upper low will drift across Atlantic Canada through the period, while a surface high sets up shop over Quebec and New England. Expect dry north-northeasterly flow to filter in with baggy upper troughiness overhead, helping to keep cooler thicknesses in place. As a result, sensible weather remains dry through the end of the workweek, with no mentionable PoPs in the forecast. Temperatures will be 5-10 degrees below normal for overnight lows thanks to radiational cooling, while afternoon highs will be only a degree or two below-normal as strong insolation reaches the surface under mostly sunny skies.
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.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 120 PM EDT Tuesday: Surface high still in control going into the upcoming weekend, while the flow aloft remains virtually unchanged. Guidance show a weak backdoor front sliding through the area Saturday night into Sunday, but will at most provide some cloud cover and a wind shift. Otherwise, the upper pattern diverges slightly closer to the end of the period as there is some support for a closed upper low developing somewhere in the eastern CONUS, but differ in the exact placement. This could be the setup to bring our next rain chances, but confidence is low at this time. Temperatures will uptick to near-normal through the weekend, with some potential of climbing a few ticks above normal by the end of the forecast period.
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.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... At KCLT and elsewhere: Prevailing VFR at all terminals not named KAVL through the period, courtesy of high pressure. At KAVL, the few remaining stratocu should dissipate with sunset, thereafter, it should be clear. Guidance suggests a similar situation tonight compared to this past morning, when IFR restrictions developed in the valley. Will start out with a prevailing MVFR and temporary IFR for vis and go from there. The fog/stratus should dissipate by 13Z. Wind will remain generally light and northerly.
Outlook: Dry and mostly VFR through the end of the week, except for the steadily increasing potential for morning mountain valley fog and/or low stratus.
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.GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None.
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SYNOPSIS...DEO NEAR TERM...PM/TW SHORT TERM...CAC LONG TERM...CAC AVIATION...PM
NWS GSP Office Area Forecast Discussion