Thundersnow marks arrival of cold front in Western Pennsylvania

Western Pennsylvanians got a rare treat overnight — thundersnow — a winter thunderstorm.

The rumbles of thunder and flashes of lightning while snow was falling startled awake Tom Bell, Greensburg’s fire chief and streets superintendent.

“I was like ‘What the hell was that?’” he said.

Bell immediately looked at remote surveillance video outside Lynch Field, which captured evidence of the phenomenon. Lightning was seen around 12:45 a.m. Thursday there.

There were 10 cloud-to-ground lightning strikes in the Pittsburgh region between midnight and 1 a.m., said Mike Kennedy, meteorologist at the National Weather Service in Moon. Certain weather circumstances have to combine for thundersnow to happen, including the mixture of warm and cold air, whereas the air is consistently cold during winter storms.

“You just need more instability and that typically doesn’t happen in the winter,” he said.

The temperature at Pittsburgh International Airport was 43 degrees late Wednesday night and dropped to 25 degrees at 5:30 a.m. Wednesday, according to the weather service.

Yes, many of you can cross thundersnow off your bucket lists tonight (the real weather geeks will understand). This line of rain, snow, and sleet has produced multiple flashes over the last hour. pic.twitter.com/AzEXdJ6l0j

— NWS Pittsburgh (@NWSPittsburgh) December 5, 2024

Thunder during snow is more rare than thunder during a summertime storm, which doesn’t need the mixture of temperatures, just some warm, moist air to create the right conditions, he said.

“During the summer, it’s more thermodynamically driven,” Kennedy said.

The Great Lakes area is where thundersnow is most common because lake effect snow falls there for a longer period of time, according to AccuWeather.

Temperatures in the region dropped overnight, turning rain into sleet and snow, according to the weather service. Varying amounts dropped around the area. Public works crews were out early treating roads and dozens of schools delayed the start of classes while some, including Ligonier Valley and Southmoreland, were closed for the day.