Strongly forced ascent associated with an upper level trough and surface cold front produced a fast-moving line of low-topped thunderstorms along the spine of the Appalachians during the afternoon. As the front crossed the Alleghenies during the late afternoon and interacted with greater instability east of the mountains, more vigorous storm development was observed with intense bowing/squall line segments producing widespread thunderstorm wind damage as they accelerated eastward through the central mountains into the ridge and valley region. Multiple reports of wind damage were verified with an isolated spin-up/gustnado confirmed in southern Clearfield County.
To the south and east of the advancing cold front, an enhanced but focused tornado threat evolved near a developing frontal wave and attendant warm front/triple point.
As the warm front lifted northward from the Baltimore/Washington D.C. area into south-central and southeastern Pennsylvania, the convective environment become very favorable for tornadoes as very strong low level wind shear overspread the area. Several rotating storm signatures were observed via radar with two weak (EF0) tornadoes confirmed in Bedford and York Counties.

Tornado in BEDFORD, PENNSYLVANIA
From 01-JUN-12 17:18:00 to 01-JUN-12 17:20:00 (EST-5)
Location: ALUM BANK
Tornado F-scale: EF0
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A storm survey team from the National Weather Service concluded that a short lived tornado touched down near Alum Bank in Bedford County. The tornado touched down at the intersection of Route 96 and Gordon Hall Road and was on the ground about one and one half miles before lifting up at the intersection of Route 96 and Township Road T606.  The tornado was embedded within a larger area of straight line winds. Maximum winds were estimated at 70 mph which damaged a barn and caused minor damage to three other structures. Approximately 30 trees were also knocked down from the storm which several witnesses reported as being accompanied by whirling clouds and a driving rain. There were no injuries or fatalities.

Thunderstorm Wind in SOMERSET, PENNSYLVANIA
From 01-JUN-12 16:40:00 to 01-JUN-12 16:40:00 (EST-5)
Location: BAKERSVILLE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees and utility wires near Seven Springs.

Thunderstorm Wind in CAMBRIA, PENNSYLVANIA
From 01-JUN-12 17:00:00 to 01-JUN-12 17:00:00 (EST-5)
Location: JOHNSTOWN
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees in Johnstown.

Thunderstorm Wind in CAMBRIA, PENNSYLVANIA
From 01-JUN-12 17:10:00 to 01-JUN-12 17:10:00 (EST-5)
Location: NANTY GLO
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees and wires in Nanty-Glo.

Thunderstorm Wind in CAMBRIA, PENNSYLVANIA
From 01-JUN-12 17:05:00 to 01-JUN-12 17:05:00 (EST-5)
Location: BARNESBORO
Magnitude: 50.00 MG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm winds measured near 60 mph knocked down utility wires and caused a small building to collapse in Northern Cambria.

Thunderstorm Wind in CLEARFIELD, PENNSYLVANIA
From 01-JUN-12 17:23:00 to 01-JUN-12 17:23:00 (EST-5)
Location: BERWINSDALE
Magnitude: 83.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An official NWS Storm Survey confirmed a microburst and gustnado near Irvona. Maximum wind speeds were estimated around 95 mph. The microburst damage began at the crest of a hill about 1/4 mile southwest of Shortcut Road, with several downed trees and significant damage to a barn roof. Microburst winds accelerated down a small valley and produced significant damage to a mobile home at the bottom of the hill before starting to swirl. Thunderstorm winds appeared to swirl back and roll a second mobile home which was tied down with straps. A small, concentrated area of trees were also knocked down on the east side of Shortcut Road. Therefore, it was concluded that a brief gustnado likely was created at the bottom of the valley before the microburst dissipated. For reference, a microburst is a convective downdraft with an affected outflow area of less than 2.5 miles and peak winds lasting less than five minutes.

Thunderstorm Wind in LYCOMING, PENNSYLVANIA
From 01-JUN-12 19:55:00 to 01-JUN-12 19:55:00 (EST-5)
Location: GARDEN VIEW
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees near Williamsport.

Thunderstorm Wind in CUMBERLAND, PENNSYLVANIA
From 01-JUN-12 20:00:00 to 01-JUN-12 20:00:00 (EST-5)
Location: CEDAR CLIFF MANOR
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds estimated near 60 mph knocked down trees and large limbs near Camp Hill.

Thunderstorm Wind in POTTER, PENNSYLVANIA
From 01-JUN-12 18:45:00 to 01-JUN-12 18:45:00 (EST-5)
Location: COUDERSPORT
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees near Coudersport.

Thunderstorm Wind in FULTON, PENNSYLVANIA
From 01-JUN-12 18:10:00 to 01-JUN-12 18:10:00 (EST-5)
Location: NEEDMORE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees and utility wires in Needmore.

Thunderstorm Wind in MIFFLIN, PENNSYLVANIA
From 01-JUN-12 18:53:00 to 01-JUN-12 18:53:00 (EST-5)
Location: REEDSVILLE ARPT
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm winds estimated near 60 mph knocked down trees near Lewistown.

Thunderstorm Wind in CENTRE, PENNSYLVANIA
From 01-JUN-12 18:05:00 to 01-JUN-12 18:05:00 (EST-5)
Location: (PSB)MID ST ARPT PHI
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Thunderstorm winds estimated near 60 mph knocked down trees over Casanova Road.

Thunderstorm Wind in CLINTON, PENNSYLVANIA
From 01-JUN-12 19:00:00 to 01-JUN-12 19:00:00 (EST-5)
Location: LOCKPORT
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds estimated near 60 mph knocked down trees near Lock Haven.

Thunderstorm Wind in BLAIR, PENNSYLVANIA
From 01-JUN-12 17:42:00 to 01-JUN-12 17:42:00 (EST-5)
Location: MILL RUN
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm winds estimated near 60 mph knocked down trees near Altoona.

Thunderstorm Wind in CLEARFIELD, PENNSYLVANIA
From 01-JUN-12 17:40:00 to 01-JUN-12 17:40:00 (EST-5)
Location: PENFIELD
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Thunderstorm winds estimated near 60 mph knocked down trees near Penfield.

Funnel Cloud in YORK, PENNSYLVANIA
From 01-JUN-12 15:26:00 to 01-JUN-12 15:26:00 (EST-5)
Location: HAMETOWN
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported a funnel cloud just north of Shrewsbury. This storm went onto produce an EF0 tornado near Winterstown.

Tornado in YORK, PENNSYLVANIA
From 01-JUN-12 15:32:00 to 01-JUN-12 15:32:00 (EST-5)
Location: ADAMSVILLE
Tornado F-scale: EF0
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A National Weather Service survey team concluded that a tornado briefly touched down in North Hopewell Township in southern York County, about 2 miles north of the town of Winterstown during the afternoon of Friday, June 1. Damage was confined to one property on Lists Road, near the intersection of Route 24, where an entire roof was lifted off a single story home, and one tree was damaged. Although damage from the tornado was limited, strong video and photographic evidence was available to support the tornado. Maximum winds were estimated at 70 mph, making this an EF0. There were no injuries or fatalities.