A lone supercell, that advanced along a cold front, formed in the early morning hours of October 16th. This cell had a history of tornadoes before tracking into eastern Ohio and western PA. The supercell was located near a mesoscale low and/or mesoscale vortex, which supported locally enhanced helicity. Furthermore, this cell was in an area of relatively stronger low-level instability. Surface dew points were favorable, low/mid 60s, prior to touch down and there were backed surface winds.

Tornado in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 07:08:00 to 16-OCT-21 07:09:00 (EST-5)
Location: SIGEL
Tornado F-scale: EF1
Property damage: 150.00K
Crop damage: 750.00K
Reported by: NWS Storm Survey

The National Weather Service in Pittsburgh conducted a tornado survey along the Clarion River that straddles Jefferson and Elk County.
A weak EF0 tornado moved north northeast shortly after daybreak on Saturday October 16th. This resulted in damage to softwood and hardwood trees along the Jefferson County side of the Clarion River along State Route 949. More significant damage (EF1) was observed on the Elk County side, along River Road. The tornado lifted just prior to reaching Bridge Road. Estimated Maximum Wind Speed...85 mph.
Estimated cost of damage was provided by the county emergency manager.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 07:16:00 to 16-OCT-21 07:16:00 (EST-5)
Location: (DUJ)DUBOIS-JEFFERSO
Magnitude: 65.00 EG
Reported by: 911 Call Center

A 911 Call Center reported electrical lines down on MC Vitty Road in Washington Township.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 07:03:00 to 16-OCT-21 07:03:00 (EST-5)
Location: SIGEL
Magnitude: 65.00 EG
Reported by: Social Media

A social media report of multiple trees down in this area.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 07:14:00 to 16-OCT-21 07:14:00 (EST-5)
Location: MUNDERF
Magnitude: 65.00 EG
Reported by: 911 Call Center

A 911 Call Center reported multiple phone lines and severe poles down along Route 949; road was closed at one point.

Tornado in BEAVER, PENNSYLVANIA
From 16-OCT-21 05:16:00 to 16-OCT-21 05:18:00 (EST-5)
Location: STOBO
Tornado F-scale: EF1
Reported by: NWS Storm Survey

A new tornado, from the same storm cell that affected Shippingport earlier, touched down in the Jackson Ave area of Monaca then continued east, uprooting hardwood and softwood trees. A car windshield was damaged due to a tree falling on it on the aforementioned street. Tree damage was visible along Elkhorn Road with numerous hardwood trees down. A mobile home lost its roof due to the storm. There was a brief lull in the damage as the tornado crossed the Ohio River into Freedom. The damage quickly picked up with damage observed on 4th Ave. The worst damage
was observed on this side of the river.
Scattered down trees and large branches were visible along 9th Ave Ext into New Sewickley Township. At the top of the hill and points east along Harvey Run Road at least 30 trees were uprooted. There was no structural damage observed apart from the awning of a front porch in the city of Freedom, which was displaced by a falling tree.
Estimated Maximum Wind Speed...85 mph.

Thunderstorm Wind in CLARION, PENNSYLVANIA
From 16-OCT-21 06:40:00 to 16-OCT-21 06:40:00 (EST-5)
Location: SLOAN GAP
Magnitude: 65.00 EG
Reported by: 911 Call Center

Multiple reports of trees down on Divens Road, damage to a house on South Reidsburg Road.

Thunderstorm Wind in BEAVER, PENNSYLVANIA
From 16-OCT-21 05:19:00 to 16-OCT-21 05:19:00 (EST-5)
Location: EAST ROCHESTER
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social media reports of damage to trees and sheds.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 05:34:00 to 16-OCT-21 05:34:00 (EST-5)
Location: BUHLS
Magnitude: 75.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A large oak tree snapped and toppled over on Old Route 68. A NWS Storm Survey concluded this was caused by straight line winds.

Thunderstorm Wind in CLARION, PENNSYLVANIA
From 16-OCT-21 06:41:00 to 16-OCT-21 06:41:00 (EST-5)
Location: REIDSBURG
Magnitude: 65.00 EG
Reported by: Social Media

Social media pictures of snapped trees and power lines down along Reisburg Road in Monroe Township.

Tornado in BEAVER, PENNSYLVANIA
From 16-OCT-21 05:06:00 to 16-OCT-21 05:07:00 (EST-5)
Location: MIDLAND
Tornado F-scale: EF0
Reported by: NWS Storm Survey

A EF0 tornado touched down in the town of Shippingport early
Saturday morning before daybreak. The damage was located on
Second Avenue with three trees being uprooted. The tornado
traveled east and blew the roof off a pavilion behind the
Shippingport municipal building then continued to uproot and tear
off large branches until it lifted before reaching Shippingport
Hill Road. Estimated Maximum Wind Speed...95 mph.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 05:20:00 to 16-OCT-21 05:20:00 (EST-5)
Location: GLEN EDEN
Magnitude: 70.00 EG
Reported by: Public

A citizen reported that a large tree was uprooted.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 05:30:00 to 16-OCT-21 05:30:00 (EST-5)
Location: CRIDERS CORNERS
Magnitude: 75.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Social media report of multiple trees damaged in Cranberry Township. A NWS Storm Survey concluded this was caused by straight line winds.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 05:53:00 to 16-OCT-21 05:53:00 (EST-5)
Location: EAST BUTLER
Magnitude: 70.00 EG
Reported by: NWS Storm Survey

Cluster of 3 large trees snapped, but no damage to anything in adjacent mobile home park or surrounding woodlands.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 06:04:00 to 16-OCT-21 06:04:00 (EST-5)
Location: CHICORA
Magnitude: 80.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Large trees snapped near the base in the vicinity of Chicora.

Thunderstorm Wind in BUTLER, PENNSYLVANIA
From 16-OCT-21 06:26:00 to 16-OCT-21 06:26:00 (EST-5)
Location: GLEN EDEN
Magnitude: 75.00 EG
Reported by: NWS Storm Survey

Trees snapped and uprooted in this region.

Thunderstorm Wind in CLARION, PENNSYLVANIA
From 16-OCT-21 06:42:00 to 16-OCT-21 06:42:00 (EST-5)
Location: LIMESTONE
Magnitude: 65.00 EG
Reported by: Emergency Manager

An Emergency Manager reported multiple trees down and roof damage to two homes in Monroe and Millcreek Township.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 06:55:00 to 16-OCT-21 06:55:00 (EST-5)
Location: SUMMERVILLE
Magnitude: 65.00 EG
Reported by: 911 Call Center

A 911 Call Center reported damage to multiple utility poles and trees.

Thunderstorm Wind in JEFFERSON, PENNSYLVANIA
From 16-OCT-21 07:03:00 to 16-OCT-21 07:03:00 (EST-5)
Location: SIGEL
Magnitude: 65.00 EG
Reported by: 911 Call Center

A 911 Call Center reported multiple trees down in Eldred Township.