A surface low pressure system was moving across the upper Ohio Valley towards the Pittsburgh area associated with showers. As the system moved over Allegheny County, it strengthened and spawned heavy rain with windy conditions. Some of the winds had mixed down with the heavy showers causing sporadic areas of damage.  Before the center of the low started crossing Allegheny County, very small vortices spun up on the southern side of the low, producing two weak and short lived tornadoes.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 16:30:00 to 27-SEP-12 18:30:00 (EST-5)
Location: CLAIRTON
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Flash fLooding was reported in Clairton, Wilkins Township, and Baldwin where a vehicle rescue was performed.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 16:55:00 to 27-SEP-12 16:55:00 (EST-5)
Location: ASPINWALL
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 call center reported 10 inches of water flowing across Nadine Road.

Tornado in WASHINGTON, PENNSYLVANIA
From 27-SEP-12 14:57:00 to 27-SEP-12 15:00:00 (EST-5)
Location: EIGHTY FOUR
Tornado F-scale: EF0
Property damage: 75.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An NWS survey found a EF0 tornado with maximum estimated speeds of 80 to 85 MPH. A concentrated damage swath was encountered along Route 519 in Eighty Four to along Brownlee road near Gambles. Damage consisted of snapped and uprooted hardwood and softwood trees and destruction of small outbuildings and modest shingle removal on a structure. A car was blown onto its side along route 519 during the tornado. This tornado also was confirmed by video submitted to the national weather service.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 17:15:00 to 27-SEP-12 18:30:00 (EST-5)
Location: BLAWNOX
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 center reported Center Ave buckling due to heavy rainfall.

Tornado in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 15:44:00 to 27-SEP-12 15:45:00 (EST-5)
Location: DUQUESNE
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An NWS survey found and EF0 tornado with estimated maximum winds of 70 to 80 MPH. Damage to trees was noted along and southwest of Grant Avenue Extension in West Mifflin. Softwood trees and large hardwood tree limbs were snapped and dragged. Cemetery headstones were blown over. The exposed front porch of a home was uplifted and deposited on the roof of the home.

Thunderstorm Wind in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 16:20:00 to 27-SEP-12 16:20:00 (EST-5)
Location: OPTION
Magnitude: 50.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 call center reported trees down.

Thunderstorm Wind in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 16:40:00 to 27-SEP-12 16:40:00 (EST-5)
Location: MILLVALE
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Severak trees were reported down in Millvale.

Thunderstorm Wind in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 15:44:00 to 27-SEP-12 15:44:00 (EST-5)
Location: DUQUESNE
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 call center reported a power pole knocked down.

High Wind in ALLEGHENY, PENNSYLVANIA
From 27-SEP-12 16:20:00 to 27-SEP-12 16:20:00 (EST-5)
Magnitude: 50.00 EG
Property damage: 35.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported trees and power lines down in Penn Hills.