The National Weather Service issued a severe thunderstorm warning for several counties in western Pennsylvania.
The warning is in effect until 7:45 p.m. for Butler, Lawrence and Mercer counties.
The storm is capable of producing quarter-sized hail and damaging winds in excess of 60 mph, according to the service.
In additon, continuous cloud to ground lightning is being reported with this storm.
"Lightning is a killer," a statement from the service said. "If you can hear thunder, you are close enough to be struck by lightning."
A severe thunderstorm also remains in effect until 10 p.m. Thursday for all of western Pennsylvania.