Flash Flood — York, Pennsylvania

2025-07-09 · near Shiloh, York, Pennsylvania

Event narrative

Flash flooding led to a basement foundation collapse in the 1700 block of Oakley Drive near Weigelstown, with water and mud reported across roadways in the area.

Wider weather episode

Convection across southern Pennsylvania began to develop in an unstable and moist environment ahead of a shortwave trough traversing the area during the afternoon and evening hours of July 9, 2025. Storms initially were sub-severe due to lower shear parameters and low-level lapse rates; however, increasing shear and lapse rates allowed for damaging wind potential within an environment of 700-900 J/kg of DCAPE. Shear oriented out of the southwest, parallel to surface boundaries, led to an increased risk of flash flooding in an environment that sustained over one inch an hour rainfall rates. Multiple instances of trees and wires being knocked down were reported in Lancaster and York counties during the evening hours. Increased rainfall rates falling over fairly moist soils of York County induced flash flooding, with multiple roadways closed in both counties during the evening hours. Heavy rain also caused a basement to collapse in Dover, with water and mud reported over nearby roadways.

View location on OpenStreetMap → (39.9940, -76.8086)

Source: NOAA Storm Events Database, event_id 1278561. Narrative written by the NWS forecast office that issued the report.