Severe storms pounded the Pittsburgh area Sunday evening with winds exceeding the speed limit on many area highways.

As many as 9,100 Allegheny Power customers had lost electricity service by the late evening. A utility representative said there were around 400 customers currently without power as of 11:30 a.m. Monday.

Duquesne Light said at the height of the storm Sunday, about 1,250 of their customers without electricity in Allegheny and Beaver counties. Duquesne Light said that number was down to around 600 as of 11:30 a.m. Monday.

The storms prompted the National Weather Service in Pittsburgh to issue a tornado warning at about 5:20 p.m. that lasted for about 20 minutes. About an hour later, sunlight broke through the clouds over Pittsburgh.

A severe thunderstorm warning took effect shortly thereafter for Fayette, Westmoreland, Greene and Indiana counties until 9 p.m. Washington and Allegheny counties had been included under the warning until the NWS canceled it a half-hour early. Similar alerts were issued throughout the early evening.

A severe thunderstorm watch for the Pittsburgh area expired shortly after 8 p.m., but remained in effect to the east of the WTAE Channel 4 viewing area into the evening.

The NWS later issued a flood advisory for Allegheny, Fayette, Washington, Westmoreland and Indiana counties to remain in effect until 11:15 p.m.

Sunday's storms dumped 1 to 2 inches of rain in addition to storms that passed through the area on Saturday. An additional inch or more of rain could cause flooding in low spots, including areas along the Pennsylvania Turnpike, Interstate 70 and U.S. Route 22.

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Action News Viewer pictures of Sunday's storms

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When the tornado warning was issued, the area under which Doppler radar showed rotation in the storm was located near Mollenauer, moving east northeast at 35 mph.

Weather Watch 4 meteorologist Erin Kienzle said Pinpoint Doppler indicated the area of greatest concern immediately after the warning was issued was just east of Oakdale headed toward West Homestead and Munhall.

Doppler radar indicated the storms were capable of producing penny-size hail and damaging winds in excess of 60 mph. Allegheny County airport officials reported a wind gust of 69 mph.

Kienzle said the storm system quickly moved at about 45 mph to the north and east. The entire line of storms stretched from Freeport south to Washington.

Storms Knock Down Trees Throughout Area

Reports of fallen trees and power lines have come into the Channel 4 Action Newsroom from Upper St. Clair, Mount Lebanon and Bethel Park areas in Allegheny County, and east of Canonsburg and Cecil Township in Washington County.

Large trees fell along Bethel Church Road in Bethel, also taking down power lines.

The storm knocked down a tree along the light rail's Library Line, closing passenger traffic at the Washington Junction station. The Port Authority said crews removed the tree and got the line back up and running.

In Cecil Township, Channel 4 Action News found downed trees and power lines on Papp Road, in addition to a tree that fell on a garage, partially onto a house. Bulldozers were called to Burnside Road, where crews used chain saws to remove fallen trees.

WTAE Channel 4's Jennifer Miele reported that the same line of storms started moving through Westmoreland County at about 6 p.m. with loud thunder, a burst of rain and wind. Dispatchers told Miele that they have received reports of trees down in the county.

Miele spoke with fire officials in Penn Township, Westmoreland County, where three fire departments are clearing trees from roads in the North Huntingdon, Greatville, Delmont and Murraysville areas.

Ross Township officials have postponed its fireworks display Sunday night as a result of the storms. All other activities will go on as scheduled.

Storms Pound Pittsburgh Area Over Weekend

Sunday's storms came after a deluge of heavy rain on Saturday. At one point Saturday, as many as 10,000 Duquesne Light customers lost power, WTAE Channel 4's Tara Edwards reported.

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Video: Beaver County Cleans Up After Storm
Slideshow: Trees Fall In Beaver County Storm

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The Midland Water Authority has asked residents in Midland, Ohioville and Shippingport to conserve water after the storm affected the water supply (More).