EF1 tornado in Washington County, Pennsylvania

A NWS damage survey confirmed that an EF-1 tornado, with winds

speeds ranging between 90 to 95 MPH, tracked through portions of

Peters Township in Washington County on the evening of October

21, 2021. The length was 1.5 miles and the width in some areas

was about 100 to 200 yards. This tornado was associated with the same

circulation that initially produced an EF-1 tornado in Jefferson

County, OH and an EF-2 in Hopewell Township a few miles to the

west.

A few broken branches were noted along Thomas Road near

Peters Lake Park. However, the tornado quickly intensified as it

cross Hill Place Road. Trees were uprooted and snapped in the

vicinity of Springdale Road and Sunrise Lane. A number of new and

well-structured brick homes had window damage, a garage blown

out, shingle damage, and trees snapped. The tornado weakened and

dissipated just west of Bower Hill Road.

A detailed review by PEMA noted damage to 4 homes on Hill Place Road,

5 homes on Sunrise Road, 5 homes on Springdale Road, 1 home on

Buckingham Drive, and 2 homes on Sienna Trail.

Damage cost was estimated by NWS Storm Surveyor.

A broken line of supercells, which formed along a front, moved quickly through the Ohio River Valley the evening of October 21st and spun off several tornadoes. The number of tornadoes, time of year, and intensity (one long track EF2 tornado) will mark this event as very rare and significant for this region.

Prior to tornado development, surface temperatures warmed into the low-mid 60s; dew points topped out near 60F. Forecast soundings indicated modest levels of mean layer CAPE, and a relatively straight hodograph yielding marginal but sufficient storm relative helicity. The overall quick track of the broken line and eastward propagation helped cells sustain rotating updrafts.