Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
009 FXUS62 KGSP 222347 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 747 PM EDT Fri Aug 22 2025 .SYNOPSIS... Chances for mainly afternoon and evening showers and thunderstorms linger through the weekend keeping the locally heavy rainfall and isolated flash flood threat around. High temperatures will end up below normal Friday into the weekend before warmer highs return briefly on Monday. Cooler and drier conditions return by Tuesday and will linger through the rest of the workweek behind a cold front. && .NEAR TERM /THROUGH SATURDAY/... As of 744 PM EDT Friday... Key Messages: 1) Unsettled weather, with periods of showers and thunderstorms again on Saturday. 2) Temperatures Saturday slightly below normal for late August. No major changes to the forecast this evening. Convection has waned across most of the area, and any further activity overnight is expected to be widely scattered at best. NE wind continues. A 500 mb anticyclone will persist over the Four Corner region, extending east to the OH Valley. A sheared vort lobe on the SE side of the upper high will persist across region, resulting in little change in the flow and air mass atop the forecast area. At the sfc, a 1020 mb high extends east-west across the southern Great Lakes to the Mid-Atlantic, with a wedge nosing south across the Carolinas. A stalled front was analyzed across the Deep South, with a weak wave forming along the boundary invof southern AL. The wedge isn`t technically cold-air damming; but has behaved in much the same way CAD would, with some sites still not fully cleared of low stratus that developed this morning. The sfc high migrates to the Northeast coast, keeping the wedge in place tonight with waves rippling along the stalled front across the Deep South. A similar set up will remain in place atop the forecast area, with another wedge-like day and continued unsettled weather. Perhaps a little more dry air punches in from the NE, shunting the isolated heavy rain/flash flood threat further S and W. Lows will be around 5 deg above normal (mainly in the 60s) under cloudy to mostly cloudy skies. The low clouds will again take a while to scatter out Saturday, but a little drying in the eastern half of the forecast area will allow max temps to be slightly warmer, but still a deg below normal. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 100 PM EDT Friday... Key Messages: 1) Shower and Thunderstorm Chances Stick Around Sunday 2) Dry Conditions Finally Return Sunday Night into Monday 3) Highs will be Near Normal to a Few Degrees Below Normal Each Day A cold front will approach from the west through Sunday before pushing across the forecast area Sunday night into early Monday morning. Behind the front, dry sfc high pressure will build into the area from the west Monday into Monday night. Aloft, upper troughing will remain over the region through the period. Mainly diurnal shower and thunderstorm chances will linger through Sunday evening before gradually tapering off behind the front Sunday night into Monday. Ahead of the front, deep layer shear will increase slightly, ranging from 20-25 kts, which could increase the strong to severe storm threat somewhat. However, with only 1,000- 1,800 J/kg of SBCAPE depicted by the global models and some of the 12Z CAMs (NAM/NAMNest/RAP), confidence on the severe threat remains low. Dry conditions will finally return to the forecast area Sunday night into Monday as sfc high pressure builds in the from the west. Much drier air will gradually filter into the region behind the front throughout Monday, allowing dewpoints to fall throughout the day. Dewpoints will drop into the 40s and 50s across the mountains and the 50s and lower 60s east of the mountains by late Monday afternoon. These will be pleasant dewpoints for late August! Highs each afternoon will end up near normal to a few degrees below normal. Lows will remain a few degrees above normal each night. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 100 PM EDT Friday... Key Messages: 1) Dry Weather Lingers through at Least Thursday 2) Rain Chances Could Return Friday but Confidence is Very Low 3) Below Normal Temperatures Expected through the Period Periods of upper troughing will develop overhead through the long term. Meanwhile, at the sfc, dry and cool high pressure will continue to build into the region from the west while gradually weakening. Dry conditions are expected through at Least Thursday but could linger through Friday. The latest GFS shows the potential for precip to return to the forecast area as early as Friday while the ECMWF and Canadian maintain dry conditions on Friday. Thus, confidence on the precip potential at the end of the period remains low, especially with the NBM only advertising slight chance (15% to 20%) PoPs across the mountain zones. Highs each afternoon and lows each night will be cool (especially for late August), running a few to several degrees below normal through the period. Afternoon temps each day should only reach into the upper 70s to lower 80s east of the mountains and the lower 60s to mid 70s across the mountains. Lows each night will dip into the mid 50s to mid 60s east of the mountains and the mid 40s to mid 50s across the mountains. So, it will feel more like fall than late August and this time we finally get the dry weather with the cooler temps. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: Still expect a moist regime to remain in place through the bulk of the 00z TAF period. Convection has waned for the evening, and little to no further activity is expected through the overnight apart from isolated sprinkles. Rather, the big story for the overnight period remains another round of patchy fog and low ceilings. MVFR to IFR ceilings should develop across most of the low terrain and mountain valleys...along with patchy MVFR fog. Ceilings should lift slowly Saturday...and guidance suggests they`ll lift somewhat faster than they did today...but still not return to MVFR until at least 18z or later for most locations. Convection will be more widely scattered in nature tomorrow. Handled this with PROB30s for the Upstate sites, and VCSH for the mountain sites. Confidence was too low for a mention at KCLT. Outlook: Shower and thunderstorm chances along with associated flight restrictions will linger through the second half of the weekend. Drier conditions will return next week. Fog and low stratus may develop each night, mainly in the mountain valleys. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...AR NEAR TERM...ARK/MPR SHORT TERM...AR LONG TERM...AR AVIATION...MPR