Heavy rain with little, if any, lightning moved along a stationary front in a tropical environment.  Moisture was plentiful, with precipitable water values of over 2 inches.  Rainfall totals reached levels that were 350% of flash flood guidance, with 1-hour rainfall totals approaching levels that were 350% above guidance and had a 0.5% annual occurrence probability.  Allegheny County activated their EOC due to the flooding and severe weather. Numerous flooding incidents were reported, and approximately 66 water rescues were needed throughout the county. Flooding damaged a number of basement foundations. Bethel Park partially activated their EOC for massive flooding.  Here, water rescues occurred in the area of the Trolley Stop Inn, with 27 persons requiring rescue. Water rescues were conducted from Scott Township to Bridgeville Borough. One female was killed in Bridgeville Borough. She left her trapped car and was swept away by flood waters. Bethel Park submitted a municipal disaster declaration.
In Westmoreland County, flash floods and heavy rains occurred throughout the Ligonier Borough, Ligonier Township, Cook Township areas of the of the Loyalhanna and Mill Creek watershed in Westmoreland County causing localized flooding, road closures, wires down, and requiring multiple water rescues to be conducted of individuals in vehicles in flooded roadways. The Ligonier Valley area in eastern Westmoreland County was especially hard hit by flooded roadways that necessitated water rescues. The Westmoreland County EOC was activated for the flooding.  The Johnstown, Cambria County Fire Department Swift Water Rescue Team was dispatched to assist in Ligonier Township.  Several areas in the county experienced heavy basement flooding and Cook Township had first floor flooding of a residence on Green Hollow Lane that required three occupants to be rescued from a rooftop. Four adults, two children, and one dog were evacuated from two other residences. Residential flooding occurred in the area of Snowman Lane and Blouch Lane that required a water rescue of one resident.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 20-JUN-18 14:35:00 to 20-JUN-18 18:00:00 (EST-5)
Location: LOYALHANNA
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.50K
Reported by: 911 Call Center

The 911 Call Center reported a number of roads in the city of Latrobe have been flooded.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 20-JUN-18 14:40:00 to 20-JUN-18 18:00:00 (EST-5)
Location: DERRY
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.50K
Reported by: State Official

The 911 call center reports that a number of roads have been flooded in the city of Derry.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 15:42:00 to 20-JUN-18 23:00:00 (EST-5)
Location: CLIFF MINE
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 1.00K
Reported by: 911 Call Center

The 911 Call Center has reported that the bottom of Mahoney Road, near Cliff Mine Road, is completely closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:05:00 to 21-JUN-18 00:00:00 (EST-5)
Location: DORMONT
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 1.00K
Reported by: 911 Call Center

The 911 Call Center has reported that Saw Mill Run Boulevard (Outbound) is closed from I-376 to Bausman Street due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:40:00 to 21-JUN-18 01:00:00 (EST-5)
Location: BOYCE
Flood cause: Heavy Rain
Property damage: 10.00M
Crop damage: 100.00K
Reported by: 911 Call Center

The 911 Call Center has reported that a number of roads in southern Bethel Park have been flooded and/or impassable. This roads include: Glendale Drive, Logan Road, O'Neill Drive, Dashwood Drive (vehicle was stuck in water). Water entered the Trolley Stop Inn restaurant, cars in the parking lot were submerged (some floating); customers had to be rescued from the building. Local newspaper reports say at least 400 homes have been damaged and two homes were damaged so severely that they became uninhabitable.  There was 1 direct injury; a young man was sucked into a storm drain while helping others trapped in the flood. He received a few bruises for this incident.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 20-JUN-18 20:00:00 to 20-JUN-18 22:00:00 (EST-5)
Location: HICKORY
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported a number of roads flooded around Hickory.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 20-JUN-18 20:00:00 to 21-JUN-18 00:00:00 (EST-5)
Location: MC MURRAY
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported a number of roads were flooded in Peters Township.

Flash Flood in WASHINGTON, PENNSYLVANIA
From 20-JUN-18 20:00:00 to 21-JUN-18 01:30:00 (EST-5)
Location: BUFFALO
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported multiple roads in Hopewell Township were flooded.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 20:15:00 to 21-JUN-18 01:30:00 (EST-5)
Location: CLIFTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported that a female became trapped in her car on McLaughlin Run Road. She got out of her vehicle and attempted to walk home, however she was swept away by the flood waters of McLaughlin Run and carried about 2 miles downstream. Her body was found the next morning. A number of small bridges were destroyed along McLaughlin Run Road and near McMillian Road. Parked cars were sweep downstream along McLaughlin Run and were destroyed. An Outback Steakhouse had severe water damage. A state of emergency was declared in Upper St. Clair; Allegheny County officials had at least 66 swift water rescues (CBS Pittsburgh).

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 15:17:00 to 20-JUN-18 16:30:00 (EST-5)
Location: INGRAM
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported that Campbells Run is overflowing its banks and flooding nearby roadways (including Campbells Run Road).

Flash Flood in FAYETTE, PENNSYLVANIA
From 20-JUN-18 16:10:00 to 20-JUN-18 23:00:00 (EST-5)
Location: SUMMIT
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 1.00K
Reported by: 911 Call Center

A number of basements and roads have been flooded northwest/southeast of Uniontown near US-40. Several roads flooded and closed in the city of Uniontown.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 20-JUN-18 20:15:00 to 21-JUN-18 00:00:00 (EST-5)
Location: LIGONIER
Flood cause: Heavy Rain
Property damage: 1.50M
Crop damage: 50.00K
Reported by: 911 Call Center

The 911 Call Center has reported numerous water rescues in Ligonier Township. The local Giant Eagle was surrounded by water and intersections on Route 30 were closed.

Flash Flood in WESTMORELAND, PENNSYLVANIA
From 20-JUN-18 16:00:00 to 21-JUN-18 01:00:00 (EST-5)
Location: KEFFER
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 100.00K
Reported by: 911 Call Center

The county 911 Call Center reported residential flooding. Loyalhanna Creek is out of its banks. Many water rescues had to be performed; in some homes residents had to be rescued from their roof. The Loyalhanna Creek at Kingston, PA gage rose from 3ft to 11.7ft (crest) in roughly 10 hours.

Heavy Rain in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:45:00 to 20-JUN-18 21:30:00 (EST-5)
Location: CRAFTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A NWS Employee measured 2.98 inches between 8:45pm and 10:30pm.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:10:00 to 21-JUN-18 00:00:00 (EST-5)
Location: RANKIN
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported that 8th Avenue at Waterfront Drive is closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 20:30:00 to 20-JUN-18 21:30:00 (EST-5)
Location: WHITEHALL
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported 2400 Block of Lebanon Church Road had a vehicle stuck in flood waters.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:30:00 to 21-JUN-18 00:30:00 (EST-5)
Location: DORMONT
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported that the 3000 Block of Banksville Road had multiple vehicles in flood waters. Broadcast media reported flooding on Tolma Avenue with cars submerged half way.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:35:00 to 21-JUN-18 01:00:00 (EST-5)
Location: MT LEBANON
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 Call Center reported that 800 Block of McNeilly Road is flooded. Also Library Road at Valley Drive is closed due to flooding.

Flash Flood in ALLEGHENY, PENNSYLVANIA
From 20-JUN-18 19:00:00 to 21-JUN-18 00:00:00 (EST-5)
Location: ROOK
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The 911 call center reported that the 1000 block of Washington Avenue has six vehicles stuck in rising flood waters. The Department of Transportation reports that US22 in both directions at exit East I-376/US22 is flooding.