Flash Flood — Allegheny, Pennsylvania

2018-06-20 to 2018-06-21 · near Boyce, Allegheny, Pennsylvania

Event narrative

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.

Wider weather episode

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.

View location on OpenStreetMap → (40.3190, -80.0756)

Source: NOAA Storm Events Database, event_id 770933. Narrative written by the NWS forecast office that issued the report.