The National Weather Service has issued a severe thunderstorm warning for Adams County, southeastern Franklin County and southwestern Cumberland County until 7:30 p.m.
At 6:27 p.m., a severe thunderstorm was located over Robinwood and moving northeast at 45 mph.
The NWS said 60 mph wind gusts were possible and it warned of potential damage to trees and powerlines.
Locations expected to be impacted include Gettysburg, Waynesboro, Wayne Heights, Bonneauville, Pine Grove Furnace, Carroll Valley, Fayetteville, Mont Alto, Walnut Bottom and Lake Heritage.
This includes Interstate 81 from mile markers 29 to 32.