Flash Flood — Allegheny, Pennsylvania

2000-08-06 to 2000-08-07 · near Countywide, Allegheny, Pennsylvania

Event narrative

Widespread flash flooding problems were reported across the county, with 51 of the county's 130 municipalities reporting some degree of storm impact. Of those 51 municipalities, 15 reported significant impact, including flooding of streets and basements, washed-away property and cars, and roadway infrastructure damage. An estimated 1200 homes and businesses in those 51 communities were impacted. The Allegheny County Chief Executive's office reported the hardest-hit communities were Baldwin, Brentwood, Hays, Mt. Lebanon, West Mifflin, and the City of Pittsburgh along the Route 51/88 corridor. The town of Hays was probably the hardest hit of all the communities, with over 75 homes and 20 commercial properties reporting heavy damage. Several cars were swept away by the floodwaters, forcing the rescue of several people who were trapped in the vehicles. The water even swept away a pleasure boat parked in a private driveway. Emergency officials also rescued several people trapped in their homes by the high water. In McKeesport, a car dealership along State Route 48 saw a 3- to 4-foot high wall of water and mud ruin 35 to 40 new cars -- an estimated $2 million dollar loss. Several businesses in downtown McKeesport, along with City Hall, received minor water damage. At The Marina at McKees Point, 16 boats were lost and a pier buckled. Elsewhere across the county, numerous reports of flooded basements, stream flooding and mudslides were received throughout the evening of the 6th and early morning hours of the 7th.

Wider weather episode

During the morning and afternoon hours of the 6th, strong thunderstorms produced between 2 and 4 inches of rain across Allegheny, Washington and Westmoreland Counties. Throughout the evening of the 6th and the early morning hours of the 7th, more thunderstorms formed and trained along a west-to-east line over these counties. These thunderstorms produced another 2 to 3 inches of rain across this area. Final rainfall totals for this event in Allegheny County include 5.71 inches at the Allegheny County Airport in West Mifflin (4.27 inches through midnight, plus another 1.41 inches during the early morning hours of the 7th), 5.55 inches in Baldwin Borough, 5.25 inches in Castle Shannon and 4.3 inches in Pleasant Hills. The Pittsburgh International Airport set a record for the 6th, recording 1.59 inches of rain. In Washington County, 3.4 inches of rain were recorded in Burgettstown from this event, and 3.2 inches in the city of Washington. In Westmoreland County, 3.3 inches fell in Jeanette, with 3.2 inches recorded in both Derry and Murrysville. Several other locations across these counties recorded rainfall ranging between 2 and 3 inches.

Source: NOAA Storm Events Database, event_id 5175137. Narrative written by the NWS forecast office that issued the report.