As recovery continues from a night of pounding rain, power outages and flash flooding, National Weather Service officials are forecasting the potential for more storms in southwestern Pennsylvania into Friday evening.

The National Weather Service’s hazardous weather outlook for the region forecasts isolated severe storms, with the main threat coming from damaging wind gusts.

Southwestern Pennsylvania — including Allegheny, Armstrong, Butler and Westmoreland counties — was put under a severe thunderstorm watch until 11 p.m. Friday. The NWS said wind gusts could get up to 70 mph, with hail and lightning.

As of 5 p.m., storms were starting in Washington and Greene counties, said Matthew Kramar, a National Weather Service meteorologist in Moon.

With multiple reports of downed trees overnight Thursday, heavy winds are the last thing hard-hit areas need.

“During the last 24 hours in Westmoreland County, we saw reports of between a half inch up to an inch-and-a-half of rain in some spots,” said NWS Meteorologist Myranda Fullerton. “And in the Smithton-Perryopolis area south of I-70, some areas saw a little over 2 inches.”

In Allegheny County, Fullerton said a swath of the storms dumped between 2 and 3 inches of rain in Oakdale, Carnegie and along the I-376 corridor west of Pittsburgh.

“And anytime we get upwards of three-quarters of an inch of rain, we see some problems along the Route 51 corridor,” she said.

More than 20,000 combined customers of local electricity suppliers remained without power on Friday morning, following strong storms that also caused flash flooding on Thursday night.

As of 9 a.m. Friday, nearly 15,000 West Penn Power customers and 5,000 Duquesne Light customers were still in the dark. Earlier, the number was closer to 30,000.

In West Penn Power territory, the largest outages were southeast of Pittsburgh, between the Elrama-Elizabeth area and Braddock Trail Park in North Huntingdon. Between 500 and 1,500 residents in each area were without power.

In Duquesne Light territory, large pockets of customers affected by outages popped up all over the map. The largest included swaths of more than 1,200 customers in Kennedy, Ross, Dormont and Braddock, 600 in both the Esplen and Sharpsburg areas, 700 in Pittsburgh’s Greenfield neighborhood, 500 in Hazelwood, and more than 800 in both Brookline and the Pleasant Hills area.

In addition to knocking out power, the storm also knocked down trees, including one that blocked the Rosslyn Farms exit on the Parkway West. According to the Trib’s news partner WPXI, crews were still working to clear the tree as of 4 a.m.

UPDATE: more clean up crews have arrived to clear tree off of Roslyn Farms exit on Parkway West. It’s closed right now. Look for updates in an hour on TV. @WPXI starts at 4:30AM. pic.twitter.com/6Ia1bq021r

— WPXIJennifer Tomazic (@JenniferTomazic) August 13, 2021

“These last four days or so, there’s been a very active storm pattern,” Fullerton said. “We had a dewpoint temperature in the low- to mid-70s in some places.”

NWS Meteorologist Rich Redmond, who grew up in Western Pennsylvania, said that when he was younger it was rare for the dewpoint to go above 70 degrees in the summertime.

“These days, it’s a lot more common,” he said. “You’re injecting a lot more moisture into the atmosphere, and now when we have thunderstorms, they’re much better at producing heavy rainfall.”

Storms with the ability to dump 2 to 3 inches of rain are more common, Richmond said, and with fewer cold fronts to push them out of the area, they can stick around and continue soaking isolated locations.

And while the recent heat is expected to break starting Saturday, the possibility of rain remains throughout the long-range forecast for next week.

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