EF1 tornado in Westmoreland County, Pennsylvania

This EF1 tornado developed within a squall line, impacting the Chestnut Ridge region of Fayette and Westmoreland Counties. The tornado, causing EF0 damage in Fayette County, caused more significant damage after crossing County Line Road and then Acme Dams Road. This included snapped large pine trees, power poles tilted at a 45-degree angle, the loss of a carport roof from a residence, and a flipped RV trailer. As the tornado crossed Claypike Road, a power pole snapped, and an outdoor structure sustained 20% roof damage. The tornado began to weaken as it ascended a hillside near Stairs Road, dissipating near Donegal Lake. However, it subsequently re-intensified a few miles downstream, between Mansville and Ligonier PA as a new tornado touchdown. Maximum estimated wind speed for this portion of the tornado track was 100 MPH.

A strongly forced band of convection developed over West Virginia in the morning ahead of an approaching front, and quickly lifted north-northeastward into Pennsylvania through the early afternoon. Despite relatively modest instability, very strong deep layer shear, along with largely unidirectional southerly flow and elongated hodographs, supported the continuation of significant severe storms. Large impact was felt from straight-line wind, with gusts in the 60 to 80 MPH range, locally higher, causing widespread damage to trees, power lines, and structures. The line of storms continued into Pennsylvania, where the environment was more favorable for tornadic development. In addition to damaging winds, a number of large hail reports were received, with some stones as large as 1.75 inch diameter. Also, embedded supercells/mesovortices produced five confirmed tornadoes during the afternoon (one of which crossed from Fayette County into Westmoreland County).