Areas of strong, damaging winds and large hail are possible as a cluster of thunderstorms moves across portions of the Palmetto state Friday afternoon and early evening. For this reason, the Storm Prediction Center has issued a Severe Thunderstorm Watch until 8 PM for the Upstate and Midlands, including Columbia, Greenville, Spartanburg, and Rock Hill.
Thunderstorms are most likely along and northwest of Interstate 20. They are likely to be in the Greenville/Spartanburg area around 3 PM, and the Rock Hill and Columbia areas between 4 and 6 PM, before moving eastward toward Interstate 95 between 6 and 8 PM.
The low in the upper atmosphere that was partially responsible for 4 to 8 inches of rain over large swaths of the state Monday through Wednesday is slowly lifting northward into the Ohio Valley. An upper air disturbance over Alabama and Georgia is expected to scoot just beneath the departing upper-level low, and is the primary reason for the strong thunderstorm potential to start the holiday weekend.
As of early Friday afternoon, temperatures were warming toward 80 degrees. Increasing humidity combined with the warm temperatures ahead of the upper air disturbance was causing thunderstorms over North Georgia to move into South Carolina. Atmospheric conditions are favorable for strong winds and large hail with the most robust thunderstorms. Widespread tornadoes are unlikely, but an isolated tornado or two is possible.
Most of the thunderstorms should weaken or move offshore by midnight. Scattered mainly afternoon thunderstorms are possible over the upcoming holiday weekend.