Showers and thunderstorms formed along a nearly stationary boundary that crept southeastward from the Great Lakes.  Precipitable water values of around 1.6 inches and weak steering flow along the boundary led to a few areas of training thunderstorms.  Rainfall amounts of 1.5 to 3.0 inches on already saturated ground led to several areas of flash flooding in Washington, Allegheny, and Westmoreland Counties.  The worst flooding was near Herminie, where up to 14 homes were impacted and a mobile home was shifted off of its foundation.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:35:00 to 10-AUG-18 18:30:00 (EST-5)
Location: ATLASBURG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The post office at 1620 Smith Township State Road was flooded according to the county emergency manager.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:20:00 to 10-AUG-18 17:15:00 (EST-5)
Location: (AGC)ALLEGHENY CO AR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that the intersection of Route 885 and Lebanon Church Road was closed due to high water.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:30:00 to 10-AUG-18 17:15:00 (EST-5)
Location: BALDWIN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the 4800 block of Streets Run Road was flooded.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 10-AUG-18 14:35:00 to 10-AUG-18 17:15:00 (EST-5)
Location: HUTCHINSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that West Newton Road and Fire Hall Avenue in Herminie were closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:40:00 to 10-AUG-18 17:15:00 (EST-5)
Location: BLAINE HILL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the intersection of Scenery Drive and Boston Hollow Road were closed due to flooding.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:52:00 to 10-AUG-18 18:30:00 (EST-5)
Location: STUDA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that Cedar Grove Road was flooded with a car submerged.

Heavy Rain in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 17:16:00 to 10-AUG-18 17:16:00 (EST-5)
Location: STRABANE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An NWS employee reported that 1.70 inches of rain fell in 1 hour and 40 minutes.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:00:00 to 10-AUG-18 18:30:00 (EST-5)
Location: LINCOLN HILL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that State Route 40 and Franklin Farms Road in North Franklin were closed due to flooding.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:00:00 to 10-AUG-18 18:30:00 (EST-5)
Location: WASHINGTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that Jefferson Avenue and West Maiden Streets were closed due to flooding.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:15:00 to 10-AUG-18 18:30:00 (EST-5)
Location: STUDA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

According to the county emergency manager, flooding occurred at 63 Cole School Road in Jefferson Township.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 10-AUG-18 16:35:00 to 10-AUG-18 19:00:00 (EST-5)
Location: HENDERSONVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported flooding at 123 Cecil Henderson Road in Cecil.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 10-AUG-18 15:25:00 to 10-AUG-18 17:15:00 (EST-5)
Location: HUTCHINSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that a vehicle was stuck in flood waters at the intersection of Derr Road and Pierce Road in Sewickley Township.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 10-AUG-18 15:29:00 to 10-AUG-18 17:15:00 (EST-5)
Location: WYANO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that 14 homes were flooded with 2 feet of water, with one mobile home knocked off of its foundation.  Route 136 and Hutchinson Road were washed out, with numerous other roads flooded in the area.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 10-AUG-18 15:29:00 to 10-AUG-18 17:15:00 (EST-5)
Location: COWANSBURG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the intersection of Apples Mill Road and Hildenbrand Road in Sewickley Township was closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:50:00 to 10-AUG-18 17:15:00 (EST-5)
Location: COCHRANS MILL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the police found a vehicle stranded with people inside at 1000 Cochran Mill Road.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:40:00 to 10-AUG-18 17:15:00 (EST-5)
Location: BRENTWOOD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the intersection of Becks Run Road and Brownsville Road were closed due to flooding, with 2 to 3 feet of water on the road.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:50:00 to 10-AUG-18 17:15:00 (EST-5)
Location: BRUCETON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that the intersection of Cochran Mill Road and Wilson Road was closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 15:10:00 to 10-AUG-18 17:15:00 (EST-5)
Location: ELIZABETH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported that Happy Hollow Road was closed from Long Acre Drive to Scenery Drive due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 10-AUG-18 14:15:00 to 10-AUG-18 17:15:00 (EST-5)
Location: PLEASANT HILLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

County 911 officials reported that the intersection of Route 51 and Lewis Run Road was closed due to flooding.