At least one tornado hit Greenville County Monday, uprooting trees, the National Weather Service in Greer has confirmed.

Other tornado sightings were reported Monday but the weather service has not confirmed those yet, spokesman Josh Palmer said.

The confirmed "weak tornado" formed in the Berea area near White Horse Road, Palmer said.

Weather service teams were in the field Tuesday morning to investigate claims of other tornadoes.

"Those teams are looking at storm damage and trying to determine whether the damage was due to straight line winds or tornadoes," Palmer said. They'll look at how the trees fell. From that, they can get a pretty good idea of whether tornadoes were present."

The two weather service teams were investigating areas where trees were toppled, including around the border of western Greenville County and eastern Pickens County, and the border between Laurens and Union counties.

One storm-related fatality was reported. In Union County, a person died when high winds overturned a mobile home, according to weather service spokesman Rodney Hinson, spokesman. The identity of the person was not immediately available.

About 4,500 Upstate homes lost power as a result of the storm, according to Duke Energy.

Power was restored by Tuesday morning to homes in Greenville County, said Duke Energy spokesman Ryan Mosier.

But some homes in Pickens County around Central still lacked power Tuesday morning.

"We have a handful of customers in the Central area that had extensive damage and we’re finishing repairs on this morning," Mosier said.

More severe weather is expected in the Upstate Wednesday, including the possibility of high winds, tornadoes and large hail.

"We're looking at another round of activity perhaps even more significant than what we saw Monday," Palmer said.

The risk is greatest from Oconee County down to Abbeville County, Palmer said.

Two back-to-back severe weather events are fairly rare for the Upstate, Palmer said.

"It's pretty unusual to have a one-two punch like that," he said.

Wednesday's severe weather is predicted to come in two waves: in the afternoon or evening, followed by a later event at midnight, according to the weather service.

Two weeks ago, the Upstate was hit by particularly large hail.

"That's fairly unusual for this area," Palmer said. "The size of the hail was definitely unusual."

But Palmer added that there was no atmospheric oddities affecting the weather in the Upstate.

"The weather is volatile and sometimes it can becomes violent," Palmer said. "There's really no large scale pattern."