Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
427 FXUS62 KGSP 250027 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 827 PM EDT Fri Jul 24 2026 .WHAT HAS CHANGED... Updated the aviation discussion for the 00z TAF issuance. && .KEY MESSAGES... 1. Potential for at least localized excessive rainfall continues through Saturday. 2. A return to typical mid-summer weather begins Sunday and continues through Tuesday, with hot temperatures and at least isolated diurnal convection expected. Another cold front may reach the area in the middle of next week. && .DISCUSSION... Key message 1: Potential for at least localized excessive rainfall continues through Saturday. Quasi-stationary frontal boundary has set up in wedge-like fashion just south of the CWA with very stable air in place. Weak upglide from overrunning tropical moisture has set the stage for ongoing showers and elevated thunderstorms across the southern half of the CWA. Some of the more potent showers and thunderstorms will have very efficient rainfall rates as PWAT values exceed 2" and a very deep warm cloud layer is evident in vertical profiles. If multiple rounds or training storms are occurring over the same area, this could lead to a localized flash flood threat this afternoon and evening, mainly across the southwest NC mountains and Upper Savannah River Valley, closer to the vicinity of the frontal boundary. With the base of the weak upper trough over the Eastern Seaboard, an embedded shortwave is expected to move within the mean flow across the area later this evening to go along with a few hundred J/kg of MUCAPE, which should provide a slight enhancement of elevated convection across the CWA. CAMs aren`t handling this well as far as coverage, but there is a signal for the convection to linger into portions of the overnight period. Confidence is too low to warrant a Flood Watch for Flash Flooding as the threat will be too localized. Highs today will struggle to even reach 80F across much of the area with overcast to broken stratus and precipitation. On Saturday, the upper trough will sharpen with more 500mb vort energy in place as this axis moves across the region. The front should sag further south, with drier air aloft filtering in. This should promote weak low-level downsloping in the northern half of the CWA, promoting clouds to scatter and allowing for more of a typical diurnal trend in convection. Heavy rainfall rates will accompany any showers and thunderstorms, which could promote a very localized area for flash flooding, but the threat is lower compared to yesterday and today as the activity will become more progressive. Afternoon highs on Saturday are forecasted to run a category or so below normal. Key message 2: A return to typical mid-summer weather begins Sunday and continues through Tuesday, with hot temperatures and at least isolated diurnal convection expected. Another cold front may reach the area in the middle of next week. Trough axis will shift and depart the area by Sunday as drier vertical columns are present with the frontal boundary continuing to push further south, away from the CWA. In return, an amplifying mid/upper-level anticyclone gradually propagates eastward from the southern/central High Plains and Rockies, while upper-troughiness remains over the northeastern CONUS. Warmer thicknesses and more sunshine will become established and allow for temperatures to trend warmer back near to slightly above normal from Sunday through Tuesday. Expect typical diurnal convection to develop over the mountains during this time frame, with less coverage slipping off the terrain and moving across the foothills and Piedmont areas. With the orientation of the anticyclone and trough over the Northeast, expect northwesterly flow aloft to be favorable for possible MCS track or two. Guidance is messy as far as exact location and timing, but will need to monitor the progression of the overall synoptic scale pattern and associated kinematics in order to gauge the overall threat level for the CWA between Monday night and Wednesday evening. The next cold front will move into the area from the northwest Wednesday and Thursday, which will help lower temperatures in response to better coverage in convection and overall cloud cover. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: Expect sct to numerous showers to continue making their way across the fcst area tonight/overnight and thru much of the morning. Cigs are currently low-end MVFR to IFR and are expected to further deteriorate later tonight/overnight into the LIFR range. Some periods of VLIFR are possible, especially within showers. Visby restrictions are more uncertain, but most terminals are expected to remain MVFR, with lower values likely under shower activity. Nonetheless, KAVL and KHKY appear more likely to go IFR visby-wise overnight. Most of the current gui- dance shows visby returning to VFR by 14z or so, with cigs taking a few more hrs to lift/sct. By 18z, all TAF sites should be VFR. Another round of showers and thunderstorms is possible Saturday afternoon/evening, but coverage should be more limited with mostly showers expected over the NC mtns. Winds will go light and VRB to calm tonight and remain that way thru tomorrow morning. They should generally remain light and VRB at the Upstate terminals and KHKY for the rest of the TAF period, but become NW/N at KCLT and KAVL later tomorrow morning. Outlook: Drying is expected for Sunday and Monday, with convection and associated restrictions look less likely. Low stratus and/or fog will be possible each morning in the mtn valleys and at any locations that receive appreciable rainfall the previous day/evening. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ CAC/JPT