Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
337 FXUS62 KGSP 131025 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 625 AM EDT Sat Sep 13 2025 .SYNOPSIS... Dry high pressure will persist over the region through the weekend. A developing low pressure system along the Carolina coast may bring rain into the area by the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 620 AM EDT Saturday... Key Messages: 1) Dry Again East of the Mountains with Spotty Showers Possibly Returning Across the Mountains this Afternoon or Evening 2) Mostly Sunny and Warm Again Today 3) Mountain Valley Fog and Low Stratus Expected Each Morning Patchy to dense mountain valley fog and low stratus developed overnight and will linger through the next hour or two before lifting as daytime mixing gets underway. Clear skies are noted elsewhere this morning. Otherwise, not much change regarding the pattern through the near term. Upper troughing lingers over the Southeast while sfc high pressure sits tight over the eastern US. This will keep mostly dry and warm conditions around, although some spotty showers may return this afternoon or evening across the mountains. Confidence on convection remains low so maintained a dry forecast for now. Highs today will be similar to yesterday. Afternoon temps east of the mountains will rebound into the lower to mid 80s. The mountain valleys will once again see temps reach into the upper 70s to lower 80s, with temps across the higher elevations ranging from the upper 60s to upper 70s. Morning lows will range from the upper 50s to lower 60s east of the mountains and the lower to upper 50s across the mountains. Mountain valley fog and low stratus will develop again overnight into daybreak Sunday, dissipating shortly after sunrise as daytime mixing develops. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 110 AM EDT Saturday: An upper low spins along the Carolina coast or coastal plain through the period. At the surface, a low pressure system associated with the upper low remains off shore or near the Carolina coast with ridge of high pressure over our area emanating from a center over New England. This keeps the forecast area dry each day, although an isolated diurnal shower can`t be ruled out over the mountains. Highs near or slightly above normal Sunday, drop a degree or two on Monday. Lows a few degrees below normal Sunday night rise to near normal Monday night. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 145 AM EDT Saturday: The model uncertainty for the medium range continues. The guidance agrees on a low developing near the Carolina coast on Tuesday and slowly moving northeast through Thursday. However a difference in location and resulting sensible weather remains. The GFS has been consistent in keeping the low off shore with a dry forecast for our area. The ECWMF has been consistent in the low developing along the coast and moving inland far enough for an easterly flow to bring moisture and precipitation into the area. The Canadian was similar to the ECMWF but now has the low farther east, but not far enough to keep precip out of our area, but less QPF than the ECMWF. The GFS and Canadian ensemble means show precip developing over the area but on the lighter side. The guidance blend keeps mainly a slight chance PoP over the area with some chance PoP over the NC Piedmont. Given the uncertainty this continues to be the path of least regret. Temps will be below normal Tue and Wed. Slight chance diurnal PoP lingers over the mountains Thu and Fri as a weak low pressure system moves east along the OH valley. Temps will be near to slightly above normal both days. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: Mostly dry and VFR through the 12Z TAF period outside of mountain valley fog and low stratus developing each morning. As of 10Z KAVL is reporting VLIFR cigs and vsbys so will hold onto TEMPO at the terminal through the early morning hours. Fog and low stratus will gradually lift after sunrise as mixing develops. VFR cu field should return this afternoon/early evening, with some spotty showers possibly developing across the mountains again. With activity expected to remain isolated, maintained a dry forecast at KAVL as confidence is very low on whether a stray shower will track directly over the terminal. Winds east of the mountains will be mainly NE this morning and afternoon before toggling more ENE briefly this evening. Wind speeds will be a little stronger today east of the mountains, ranging from 5-9 kts. Winds east of the mountains will then toggle back to a more N/NNE direction late this evening into tonight while becoming light. Winds at KAVL will be light and VRB to calm through daybreak before toggling more NE after daybreak and eventually more E/ENE this afternoon into early this evening. Winds at KAVL will then go light and VRB to calm again late this evening into tonight. Another round of mountain valley fog and low stratus will develop overnight into daybreak Sunday. Outlook: Mostly dry and VFR through early next week, outside of the potential for mountain valley fog and/or low stratus each morning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...RWH NEAR TERM...AR SHORT TERM...RWH LONG TERM...RWH AVIATION...AR