Sep 1, 2021
The remnant low pressure center of Hurricane Ida passed across West Virginia and the Central Appalachian Mountains from late August 31st through September 1st. The abundant moisture associated with the low intersected a frontal zone which was nearly stalled in the area of the Ohio Valley. Strong isentropic and frontogenetically-induced lift led to periods of heavy rain over much of southwestern Pennsylvania over the two-day period, both from thunderstorms ahead of the low and from a period of
Source: NOAA National Weather Service Storm Events Database (event 979034). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Allegheny County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.