Why have we seen an increase in tornadoes in Western Pennsylvania?

As seasons change and temperatures rise, could we see more extreme weather, like tornadoes?

We usually see reports of twisters during severe weather season -- between now and July.

But we’re now seeing more of them in the fall and winter.

“It was about 8 o clock. You couldn’t see it coming. I think that was the thing that surprised everybody, you couldn’t see it coming. You could hear it, but you couldn’t see it,” said Ed Oehling.

Oehling heard it before he saw it. Then his outdoor light kicked on and he knew he and his daughter were in trouble.

“I couldn’t see past my porch, it was like all grey, that sound I heard it was growing, I mean it was growing and growing and getting louder and louder and that’s when I started to see debris starting to fly inside the grey and I just yelled ‘get down to the basement,” he said.

It came in fast, and then it was gone.

Six months later, Oehling has picked up the pieces and repaired his roof, but Drone 11 still shows the unmistakable signs of tornado damage -- twisted trees and a hillside that will never be the same.

The tornado that touched down there was just one of 11 tornadoes that touched down in Western Pennsylvania that night.

It was part of a line of storms that blew through four counties and the biggest tornado outbreak ever in October, making 2021 a record tornado year.

“So we had a lot of tornadoes in October, more so than we had in the last seventy years combined. So from 1950 to 2020 there’s only been 11 documented tornadoes in October, and we exceeded that by having 16 in the month across our forecast area,” said Fred McMullen, the Warning Coordination Meteorologist at the Pittsburgh National Weather Service office.

A few factors set off the October storms: Warm moist air made it seem like springtime, and a strong storm front and a La Nina weather pattern helped get the layer cake of winds and air masses spinning.

“In October, we had all those ingredients come together on multiple days that produced severe weather and tornadoes across Western PA,” McMullen said.

Tornado reports have been trending up. Each of the last five years, our area has seen at least 10 tornadoes. Part of the reason why may be that the building blocks for severe weather, warm air and moisture, are more readily available, making it easier for tornadoes to spin up any time of the year.

“What we’re seeing is tornadoes outside our peak season which typically runs from the latter half of May through the first week of July,” McMullen said.

Connecting climate change to the rise in tornadoes is complicated, but we do know that warmer temperatures may be a signal. As that warmer air bleeds further into spring and fall, it’s a reminder to be weather ready at any time.

We know part of the reason may be the warming climate or changing conditions, but it’s hard to nail down.