The National Weather Service issued a flash flood warning for central Allegheny County Thursday that is in effect until 7:45 p.m.
The weather service also stated funnel clouds have been reported, but did not state specifically where the spottings were.
Flooding has been reported in Baldwin, Clarion and Wilkins townships, according to the National Weather Service.
A flood advisory is in effect until 8:15 p.m.
"At 6:02 p.m. showers and isolated thunderstorms with strong wind gusts were along a line from three miles south of Freeport to Monroeville, moving east at 20 mph," according to the weather service.
Wind gusts of 40 to 50 mph are possible with these lines of showers and heavy rain will pond quickly in poor drainage areas, NWS states.
"At 5:40 p.m. National Weather Service Doppler radar indicated very heavy rain from a thunderstorm near downtown Pittsburgh moving east at 20 mph," the NWS website states.
Flooding is occurring or is imminent, the weather service states.
"Most flood-related deaths occur in automobiles, so do not cross water-covered bridges, dips or low water crossings," the weather service states.
The service stated strong showers will affect Allegheny, Butler, Armstrong, Indiana, Washington and Westmoreland counties.
"Funnel clouds have been reported and could possibly touch down with some of these showers. Minor damage is also possible. Wind gusts to 50 mph are possible with these showers," according to the National Weather Service.
"National Weather Service Pittsburgh radar showed heavy rain moving through Allegheny County. Up to 1 inch may fall in a two-hour period," the NWS website states.
"Leaves and other debris may clog storm drains, causing flooding in low spots," the weather service states.
Excessive runoff from heavy rainfall will cause raised levels on small creeks and streams, as well as ponding in urban area on highways, streets, underpasses, poor drainage areas, and low-lying spots, the weather service warns.
Route 51 near Lewis Run Road in Pleasant Hills is closed because of flooding.