EF1 tornado in Washington County, Pennsylvania

A NWS damage survey, conducted both by ground and aerial drone,

confirmed that an EF-1 tornado, with speeds ranging between 80 and

90 mph, tracked through eastern portions of East Finley township

on the evening of October 21, 2021. The tornado initially touched

down on open farmland approximately 0.4 miles west of Quaker Ridge

road, where drone footage discovered damage to several trees

along opposing tree lines, with a distinct scouring pattern

observed in the open pasture between them. The tornado continued

eastward through wooded area, producing the most significant

damage to a cluster of trees along Quaker Ridge Road adjacent to

the parking area for Pennsylvania State Games lands. At least 10

mature trees of up to 8 inches in diameter were snapped anywhere

from 1/4 to 3/4 of the way up the trunk line. The tornado

continued east across Quaker Ridge road into the woodlands for

another 100 ft, producing lesser tree damage until dissipating.

This damage is coincident with a strong radar signature from both

the NWS Pittsburgh and Pittsburgh International Airport Doppler

radars. A thorough survey of the area several miles west and east

of this tornado yielded no additional damage.

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.