On August 28th, a weak crossing surface low and an advancing upper trough helped to create additional thunderstorms, which were also aided by deep tropical moisture from the remnants of Hurricane Laura. Two waves of thunderstorms occurred on this day.  The first, along a lingering frontal boundary, caused wind damage to a few areas north of Pittsburgh.  A second round of storms, resulting from the crossing shortwave and deeper moisture, mainly resulted in heavy rain across portions of southwest Pennsylvania.  Urban flash flooding occurred in Allegheny County, with several reports received.  At least two vehicles were reported to be stuck in flood water.

Thunderstorm Wind in MERCER, PENNSYLVANIA
From 28-AUG-20 08:00:00 to 28-AUG-20 08:00:00 (EST-5)
Location: HENLEIN
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Trees were reported to be blown down around town.

Thunderstorm Wind in MERCER, PENNSYLVANIA
From 28-AUG-20 08:00:00 to 28-AUG-20 08:00:00 (EST-5)
Location: GREENVILLE MUNI ARPT
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Multiple trees were blown down near the Mercer/Crawford County border.

Thunderstorm Wind in MERCER, PENNSYLVANIA
From 28-AUG-20 08:07:00 to 28-AUG-20 08:07:00 (EST-5)
Location: FREDONIA
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Trees were reported to be blown down in the vicinity of Band Hill Road.

Thunderstorm Wind in VENANGO, PENNSYLVANIA
From 28-AUG-20 08:44:00 to 28-AUG-20 08:44:00 (EST-5)
Location: CLINTONVILLE
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Wind damage to trees was reported along Route 308.

Thunderstorm Wind in CLARION, PENNSYLVANIA
From 28-AUG-20 09:10:00 to 28-AUG-20 09:10:00 (EST-5)
Location: KNOX
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: 911 Call Center

In Knox along route 338, trees and power lines were reported to be down.

Thunderstorm Wind in CLARION, PENNSYLVANIA
From 28-AUG-20 09:34:00 to 28-AUG-20 09:34:00 (EST-5)
Location: MAYPORT
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: State Official

Numerous trees were reported to be down in Mayport.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 11:43:00 to 28-AUG-20 11:43:00 (EST-5)
Location: WEST MIFFLIN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Multiple reports of flooded basements were received from the West Mifflin area.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 11:47:00 to 28-AUG-20 17:30:00 (EST-5)
Location: DRAVOSBURG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Flooding was reported at the intersection of Elizabeth Road and Maple Avenue.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 12:12:00 to 28-AUG-20 17:30:00 (EST-5)
Location: WILLOCK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Streets Run Road was closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 12:17:00 to 28-AUG-20 17:30:00 (EST-5)
Location: BALDWIN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Flooding caused a road closure at the intersection of Streets Run Road and Brentwood Road.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 12:17:00 to 28-AUG-20 17:30:00 (EST-5)
Location: MC KEES ROCKS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

A foot of water was reported in a local basement.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 12:32:00 to 28-AUG-20 17:30:00 (EST-5)
Location: MC KEES ROCKS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

A vehicle was stuck in two feet of water near Chartiers Creek.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 13:43:00 to 28-AUG-20 17:30:00 (EST-5)
Location: CLIFF MINE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flooding was reported on both side of Park Manor Boulevard.

Hail in FAYETTE, PENNSYLVANIA
From 28-AUG-20 16:27:00 to 28-AUG-20 16:27:00 (EST-5)
Location: FARMINGTON ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 28-AUG-20 11:44:00 to 28-AUG-20 17:30:00 (EST-5)
Location: (AGC)ALLEGHENY CO AR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A report of a car submerged in water was received.  The occupant was rescued by police.