Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
846 FXUS62 KCAE 210553 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 153 AM EDT Fri Aug 21 2026 .WHAT HAS CHANGED... Aviation Discussion updated for 06z TAFs. && .KEY MESSAGES... - 1. Severe weather and flash flooding possible Friday. && .DISCUSSION... KEY MESSAGE 1: Severe weather and flash flooding possible Friday. The forecast for Friday largely remains on track as troughing over the eastern CONUS strengthens with another shortwave gradually working toward the region. Along with this upper support, a surface front is also expected to shift into the region through the day. Robust heating is expected through the morning into the afternoon with surface dewpoints in the low to mid 70s. This should quickly bring MLCAPE values near 2500-3000 J/kg with steep low level lapse rates bringing DCAPE values near 800-1000 J/kg. Enhanced kinematics with surging PWAT`s to near 2" will bring the risk for wet microbursts in convection during the early afternoon. While damaging wind gusts are the primary threat, cannot rule out some hail as fairly thick CAPE profiles are seen in the hail growth zone. This is further supported in analog soundings with multiple analogs for near severe hail when pulling forecast soundings from the RAP/HRRR/RRFS. 12z guidance indicates convection could get going as early as 16- 19z, quickly expanding in coverage through the afternoon and into the early evening. The overall storm motion is expected to be fairly slow (under 20 kts) and the environment appears primed for heavy rainfall with deep warm cloud depths, nearly boundary parallel deep layer shear vectors, and PWAT`s near 2". The recent REFS and HREF PMM QPF amounts show spots of 2-4" near portions of the Pee Dee and northern Midlands, which is reasonable, but both of these ensembles are keying in on amounts near 3-6" just across the CWA border in southern NC. Any southern shift in forcing/ this axis of higher QPF could bring the higher amounts in the Pee Dee and northern FA. Overall, some uncertainty remains in the exact placement of the heaviest rainfall, but isolated to scattered instances of flash flooding will be possible mainly along and east of the I-26 corridor. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR conditions expected through this morning, with restrictions expected in convection this afternoon and evening. Quiet weather is in place across the area currently. There have been some persistent showers and storms across the upstate and southern NC over the last several hours but we have remained quiet. Moisture is forecast to return in a hurry ahead of an approaching surface low and surface trough on Friday morning. Southerly and southeasterly flow will continue to push higher PW air in place as a surface low develops overhead. Convection is expected to begin early again - likely between 15z and 17z. Forecast soundings are quite impressive for this setup, with plenty of moisture and instability to yield widespread, strong thunderstorms throughout this afternoon. Given robust forcing (esp for August), plentiful moisture, and strong instability in place, feel comfortable targeting the 17z-21z timeframe for a TEMPO for TSRA, lowered visibilities, and strong wind gusts. This may need to be adjusted if convection begins earlier but this seems like a good starting point for the TEMPO group. Expecting the convection to likely wind down in the 21z to 00z timeframe, with rain showers expected to persist into the evening hours. Clouds will be copious during this time, and as the aformentioned surface low and surface boundary move to our south/east by tonight, guidance is hinting at some MVFR or IFR cigs developing. This is pretty uncertain right now but if rainfall is widespread and persistent enough, it won`t be tough to get some ceiling restrictions. Have trended towards this beginning in the 03z group. EXTENDED AVIATION OUTLOOK...Thunderstorm chances remain into the weekend, with scattered to widespread convection expected. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$ DISCUSSION...CJR AVIATION...PL