Evening storms threaten Fourth of July; flooding a concern

There’s going to be a risk of showers and thunderstorms across the region this Fourth of July, a National Weather Service meteorologist said.

A flash flood watch was in effect for Fayette and Westmoreland counties until midnight, meteorologist John Darnley said.

At 6 p.m., the weather service issued a flash flood warning for several communities in and around the Allegheny Valley area that was to be in effect until 9 p.m. Radar was indicating heavy rain, according to the warning.

Communities at risk of flooding include Ross, McCandless, Shaler, Plum, Hampton, O’Hara, Fox Chapel, Arnold, Tarentum and Springdale.

Flash Flood Warning including Allison Park PA, Glenshaw PA, Oakmont PA until 9:00 PM EDT pic.twitter.com/PRkTR9Zomv

— NWS Pittsburgh (@NWSPittsburgh) July 4, 2019

The forecast high for Thursday is 85 degrees. It’s also muggy, with dew points over 70 degrees at noon. Dew points over 60 are generally considered uncomfortable; when over 70, it’s oppressive.

Showers were popping up at midday along the eastern ridges from Fayette County up into Westmoreland and Indiana counties, Darnley said.

“A lot of the showers are going to be stationary with little movement,” he said. “They will be developing and dissipating and reforming throughout the afternoon and into this evening.”

We (and our neighbors) have issued a flash flood watch this afternoon/evening. Coverage is expected to continue to expand through the afternoon. It should be noted that heavy rain is still possible outside of the watch area from slow moving thunderstorms. pic.twitter.com/TriNLesRsU

— NWS Pittsburgh (@NWSPittsburgh) July 4, 2019

Rain is possible throughout the region, ranging from a light shower to severe weather, Darnley said. Flash flooding will be the main threat.

Most storms will be seen between 4 p.m. and 9 p.m., he said.

“Everybody has a chance of getting one,” he said.

As for the fireworks show in Pittsburgh, they’re in the same boat as everybody else, Darnley said.

“We could see some pretty significant storms develop, or we could have no rain at all,” he said. “It’s going to be widely scattered. Some areas won’t see anything and some areas will see an inch and a half (of rain).”