Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
169 FXUS62 KCAE 121821 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 221 PM EDT Wed Aug 12 2026 .WHAT HAS CHANGED... A Heat Advisory may be needed later this week. Aviation discussion updated for 18z TAFs. && .KEY MESSAGES... - 1. Heat Index between 105 and 110 possible Thu and Fri - 2. Strong storms possible today, rain chances pick back up late this weekend and early next week. && .DISCUSSION... - 1. Heat Index between 105 and 110 possible Thu and Fri Ridging aloft shifts further east late Thursday and Friday helping to suppress convection and pushing daytime highs into the mid to upper 90s, possibly around 100 degrees. Downslope winds are expected over the region with adiabatic heating helping to push temps above normal both days. Thursday: the ridge axis will still be to our west which could allow shortwave energy to dig down into the forecast area and promote convection with just a weak capping inversion in place. Downslope flow and deep mixing will allow dewpoints to drop into the low 70s or around 70 degrees in the afternoon. The NBM, which had Td values 5 to 8 degrees too warm the previous day was disregarded. We should see Heat Index values reach 105 for most areas Thursday, but a few locations could near 108 (Heat Advisory criteria). Between the chance of afternoon convection and marginal HI values, we believe confidence is too low to issue a Heat Advisory at this point. Friday: With ridging almost directly overhead we should see greater suppression of convective development. Temperatures will once again approach 100 degrees. Even after accounting for the warm bias in the NBM, dewpoints should be high enough to near or possibly exceed Heat Advisory criteria. - 2. Strong storms possible today, rain chances pick back up late this weekend and early next week. Wednesday: Storms developing across the Midwest will likely dig into the Southeast/Mid-Atlantic States later today and this evening. Similar to the previous day models show this convection diminishing through the evening. Given the verification from the previous night, there is concern that the cold pool driven system will hold together longer than CAMs show. So it appears there will be a low chance of severe weather due to a large scale outflow moving through the FA late this evening or overnight. Strong winds will be the greatest concern but there could be pockets of severe winds in some of the deeper convection. Global ensembles favor ridging flattening out late this weekend and early next week with troughing possibly developing over the eastern US near the end of the forecast period. Atmospheric moisture will be above normal during this time frame with mean PWAT values near or above 2 inches. Above normal moisture and zonal flow favors at least a chance of showers and thunderstorms each day. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... VFR conditions generally expected through the TAF period, with TSRA possible this afternoon and evening but timing remains uncertain. VFR conditions are being noted through the TAF period. With cloud debris hanging around, convective initiation has held off locally thus far. Still anticipate some development later this afternoon/evening, but confidence is low that the terminals will be affected, so leaving the VCSH in for the time being and will amend as needed should convection threaten any of the TAF terminals. Outside of thunderstorm chances, winds are forecast to be WNW around 8-10 kts before transitioning to more southwesterly around 20z-21z. Winds become light and variable to calm overnight, increasing out of the west after about 15z. EXTENDED AVIATION OUTLOOK...Diurnal chances for thunderstorms continue each day through the weekend. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$ DISCUSSION...CJR AVIATION...29