Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
500 FXUS62 KGSP 051051 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 651 AM EDT Fri Sep 5 2025 .SYNOPSIS... Temperatures will warm through Saturday ahead of a stalled front to our northwest. Afternoon and evening showers and storms are expected again today, and especially on Saturday when the front finally pushes into the area. Cooler and drier weather returns next week behind the front. && .NEAR TERM /THROUGH TONIGHT/... As of 647 AM EDT Friday: Areas of fog are visible on satellite this morning across much of the NC Foothills and Piedmont, with many ob sites reporting <1 mile visibility. As such, an SPS for Dense Fog is in effect through 14z...by which point the onset of daytime heating should have thoroughly scattered out any lingering fog. Temperatures remain on track to bottom out in the lower 60s this morning. No major adjustments were made to the forecast. Broad upper troughing will continue across the Carolinas throughout the near term, while a robust cold front will remain stalled across the upper Ohio Valley. We`ll therefore remain within a fairly moist and warm regime today, with dewpoints in the lower 70s, and southwest winds winds supporting weak moisture advection into the region. With little to no disturbance in the upper pattern, convection is expected to remain fairly sparse today, at least compared to yesterday`s; initiation should occur across the Appalachians, after which the new 06z CAMs still depict a line of cells making a run at the NC Piedmont with limited success. Should this occur, the severe risk will be more limited than on Thursday, given instability generally below 2000 J/kg and the better deep shear found west of the NC-TN state line. Still, a couple of strong storms and maybe a severe or two can`t be ruled out. Tonight, whatever convection develops will wane. Another round of fog across the mountain valleys, and perhaps some patchy fog in the Foothills, appears likely. Saturday morning`s lows will be up to a category warmer than this morning`s...and the front will edge ever closer to the Carolinas...finding itself on our western doorstep by the end of the period Saturday morning. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 105 am Friday: The long wave trough will make a quick return to the East by the end of weekend, as a series of strong speed maxima dig across the northeast quadrant of the Conus. Attendant height falls will allow a frontal zone to surge through our forecast area on Saturday. Very warm conditions are expected to continue ahead of the front, with max temps of around 5 degrees above climo expected...many locations likely reaching the 90 degree mark across the Piedmont. This combined with ample low level moisture is expected to result in moderate destabilization...sbCAPE likely in the 1500-2000 J/kg range during the afternoon. Scattered-to-numerous convective coverage is expected along the front, with PoPs mostly in the 40-70% range (highest across the mountains). Forecast wind profiles are largely unidirectional... with weak low level shear. However, deep layer shear in the 25-30 kts range could result in a few longer-lived single cell storms that producing strong-to-briefly damaging wind gusts and perhaps brief large hail. The front and any convection will shift east of the CWA during Saturday evening. Just enough moisture could linger on Sunday to allow for isolated diurnal convection across the southeast fringe of the area, and perhaps the southern mountains, but chances are at most 20% in these areas. Cooler and drier air will otherwise gradually filter into the area during the latter half of the short term, with max temps expected to be around 5 degrees below climo on Sunday...followed by min temps of 5-10 degrees below normal Sunday night. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 125 am Friday: The long wave trough over the region at the start of the period is expected to briefly retrograde early in the week, before returning by mid-week, after which heights are expected to begin rising as upper ridging begins nudging into the East. Regardless, some degree of low level high pressure is expected to be in control over the East for the balance of the extended, resulting in anomalously cool and dry conditions. Some global guidance sources attempt to pull moisture back into the forecast area during mid-week, as weak surface development occurs near the Southeast Coast. However, the consensus of deterministic and ensemble guidance suggests PoPs will be less than 20% through the period. Temps are forecast to be 5-10 degrees below climo until at least Thursday, when temps are expected to fall just shy of normal under rising heights aloft. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: Widespread IFR to LIFR fog is in place across the NC Foothills and Piedmont; but the only TAF site currently affected is KHKY (it`s very close to KCLT, but not quite there). Went ahead and introduced a quick 1h TEMPO for MVFR fog at KCLT, then a return to VFR by 13z as the fog bank scatters out. Otherwise...a round of isolated to widely scattered convection is still expected to initiate over the mountains, then translate eastward into the Foothills and perhaps the Piedmont...though confidence is low...and coverage at this time doesn`t warrant any more than a VCSH mention in any of the TAFs. Another round of fog appears possible tonight, and better coverage of convection appears likely on Saturday over the western half of the terminal forecast area, toward the end of the 12z TAF period...as a cold front approaches from the west. Outlook: A cold front brings a chance of showers and thunderstorms on Saturday, mainly over the mountains. Fog and/or low stratus is possible each morning, especially in the favored mountain valleys. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JDL NEAR TERM...MPR SHORT TERM...JDL LONG TERM...JDL AVIATION...MPR