Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
012 FXUS62 KGSP 211136 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 736 AM EDT Fri Aug 21 2026 .WHAT HAS CHANGED... The aviation forecast was updated for the 12Z TAF issuance. && .KEY MESSAGES... 1. More widespread coverage of showers and thunderstorms is expected across the area this afternoon through this evening. A few storms may be severe, producing damaging wind gusts. There will also be a threat of locally heavy rainfall and isolated flash flooding. 2. Drier weather returns Sunday and continues into early next week. A return of afternoon shower and thunderstorm chances is expected by midweek. && .DISCUSSION... Key message 1: More widespread coverage of showers and thunderstorms is expected across the area this afternoon through this evening. A few storms may be severe, producing damaging wind gusts. There will also be a threat of locally heavy rainfall and isolated flash flooding. A digging upper trough combined with high PWATs will result in an active convective day across the area. An MCS has overperformed as it crosses the western half of the forecast area, but has been on a gradual weakening trend as it pushes into the NC Foothills and Piedmont. This system has added some uncertainty on how the next round of convection will evolve. The debris cloudiness and lingering showers and storms have worked over a good chunk of the forecast area this morning. Already, the latest HRRR and 06z NAMnest are now showing convection firing along the eastern edge of the residual cold pool in the Charlotte area early this aftn, but a notable lack of activity across the rest of the area. There may still be enough time in the daylight heating hours to allow another round of convection to form across the Blue Ridge and track east late aftn/early evening. There is some signal for locally heavy rainfall, especially across the southeast third or so of the forecast area. Parts of the Charlotte area did receive some decent rainfall last night, setting up elevated soil moisture. A Flood Watch was considered, but confidence on where the heavy rain sets up is still too low. Some guidance keeps it mostly just east of the CWFA, with a secondary maximum along the eastern Blue Ridge Escarpment. The 00z HREF has some 3"+ PMM QPF bullseyes around Charlotte in the 21-00z time frame. The REFS is similar, but a little south and east. So the conditions bear watching and Flood Watch may be issued later this morning for parts of the CWFA, if confidence increases. The other concern today will be a severe threat. Pockets of 2000+ J/kg of sbCAPE, along with 25-30 kt of 0-6 km shear could support a few severe storms organizing along outflows and producing damaging wind gusts. Very moist profiles should limit DCAPE somewhat, and limit cold pool formation. Nevertheless, the new Day 1 Convective Outlook has Charlotte and vicinity in a slight risk, and most of the rest of the CWFA in a marginal risk for damaging wind gusts. Key message 2: Drier weather returns Sunday and continues into early next week. A return of afternoon shower and thunderstorm chances is expected by midweek. An eastern Conus upper trough will continue to dig on Saturday, but the axis will shift slightly east. This should allow some drier air to filter in from the west, as a slow-moving cold front will still be in the eastern part of the CWFA. There will probably be enough lingering moisture combined with cooler air aloft to allow for scattered diurnal convection to develop again across the area. PoPs will be mainly in the low-end chance range, highest east. The upper trough axis shifts further east on Sunday, and ushers in drier, more stable air completely into the region. Dry weather with seasonably warm conditions is expected Sunday through Tuesday. Then, the trough will lift northeast and bring back warmer, more humid conditions and a return to diurnal convection by the middle of next week. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: A line of thunderstorms has overperformed this morning, but is finally weakening as it crosses the KGMU/KGSP sites. Cannot rule out TS at KHKY or KCLT this morning, but chances are down to under 30%, so will go with just VCSH for that activity. Later today, still expect numerous to widespread SHRA and TSRA, especially around KCLT. With this morning`s activity working over the Upstate and NC mtns, confidence actually decreased on TSRA at those sites (will keep PROB30 for now). But the TEMPO TSRA at KCLT still looks good. Convection may linger into the evening, with highest confidence over KCLT, so will have a PROB30 for more TSRA there. Will leave out of the other sites for now. MVFR to IFR stratus may start developing after the rain ends late this evening across the area, with more widespread IFR cigs after 06z and lingering into Saturday morning. Winds will be quite VRB thru the period, especially around thunderstorms, but should favor a NE direction this morning, then S/SE this aftn. Outlook: Isolated to scattered afternoon SHRA/TSRA may develop again Saturday. By Sunday, a drier pattern should arrive and last through the first half of next week, possibly keeping SHRA/TSRA to a minimum those days. Mountain valley fog and low stratus will be possible each morning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ ARK