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2021 sets a record for tornadoes in western Pennsylvania

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National Weather Service
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Twitter @NWSPittsburgh
This graphic shows the area of Allegheny County that was under a tornado warning Thursday.

Extreme weather in western Pennsylvania has led to a record-setting number of tornadoes around the region.

The National Weather Service office in Pittsburgh, which covers parts of eastern Ohio, western Pennsylvania and northern West Virginia, typically sees three to four twisters per year in its area.

But 28 tornadoes have been confirmed by the agency in all of 2021. There have been 10 counted in October alone.

Jason Frazier, a meteorologist with the weather service, said it’s likely the region will surpass the previous record for October after the agency completes its survey of the affected areas from Thursday’s storm.

“We actually have had a very busy year with tornadoes,” Frazier said.

It’s also unusual to see high tornado activity in October, he noted. The weather event is most common in May and June.

Not everyone in Allegheny County alerted

Parts of Allegheny County were under a tornado warning Thursday, but not everyone received an emergency alert.

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A screenshot of an emergency alert sent for parts of Allegheny County

During an emergency, authorized public safety officials — including the weather service— send alerts through the Federal Emergency Management Agency's Integrated Public Alert and Warning System to participating wireless carriers, which then push the alerts to compatible mobile devices. Alerts are broadcast to the geographic area affected by an emergency.

Location is determined by the cell tower nearest to a device.

But in some cases Thursday, households were divided. In one case, a resident in the kitchen was alerted while another in the living room was not.

According to Frazier, that could be due in part to an update of the wireless emergency alert system.

Previous versions of the program sent alerts to anyone within an affected county. Those in the southern portion of Allegheny County who did not fall into the tornado warning zone would have received an alert.

But the recent update has allowed the alerts to be even more geographically specific.

Not all phones are using the latest version of the alert program, so older devices could have been pinged while newer models were never alerted. The update is an attempt to be more accurate, as well as avoid desensitizing people to storm alerts, according to Frazier.

“If people are constantly warned about tornado threats but don’t ever see anything, they will become less likely to respond to a warning that actually may impact them in the future,” Frazier said.

You can find out which version of the Wireless Emergency Alert system your device is using by contacting your wireless carrier.

More tornadoes are expected to be counted

Radar data in Pennsylvania Thursday indicated three twisters swirled near Mt. Nebo and Hampton in Allegheny County and Buffalo Township in Washington County.

Surveyors for the weather service confirmed five tornadoes connected to Thursday’s storms by late Friday afternoon.

Frazier said survey teams will continue examining the damage from Thursday’s storms through the weekend.