Flash Flood — Allegheny, Pennsylvania

1997-07-01 · near Pitcairn, Allegheny, Pennsylvania

Event narrative

A nearly stationary thunderstorm formed over the eastern part of Allegheny County during the evening of July 1. The storm dropped near 4 inches of rain in about 90 minutes over a 4 square-mile area. The resulting flash flood was centered in a small watershed in and near Pitcairn. Radar estimated rainfall rates greater than 2 inches per hour for almost 40 minutes. A rain gage at the Gateway Middle School indicated 3.30 inches storm total. Most of the damage was along Dirty Camp Run and Abers Creek. The town of Pitcairn was particularly hard hit. The streambed of Dirty Camp Run, a tributary of Turtle Creek, flows through the heart of the urbanized area of Pitcairn, where the channel is made of stoneblock and mortar. The channel flows directly under an elementary school. During the height of the flood, water was flowing through the lower level windows of the school and several walls were destroyed. The basement of a church was also completely flooded.The ferocious flood waters shoved homes from their foundations and floated and overturned numerous vehicles in the flood water's path. Approximately 429 homes, 12 businesses, 2 sewer systems, 1 park and 13 roads and bridges were affected in Pitcairn, Monroeville, Turtle Creek and Wilkins Township. Thirteen structures in Pitcairn were moved from their foundations. There were some indications of possible debris damming upstream of the greatest damage in the 5 to 6 square city block area near the lowest part of the town.A mudslide was reported along Route 22 at a gas station near the Pennsylvania Turnpike entrance. At the intersections of Routes 130 and 48, a 15 foot bridge across a Turtle Creek Tributary was washed out. Nearby, a 21 year-old male firefighter was leading a team of firefighters checking cars for occupants during the flood and became lodged under a truck in several feet of water. The firefighter died on the evening of Thursday July 3.

Source: NOAA Storm Events Database, event_id 5623088. Narrative written by the NWS forecast office that issued the report.