EF0 tornado in Butler County, Pennsylvania

A damage survey confirmed a discontinuous tornado path causing

sporadic tree damage of varying intensity as it tracked across

central Butler County. The most significant damage was noted

along Woodcrest Road, where numerous trees were snapped or

uprooted and flagpoles were bent over by the wind. Damage was

consistent with wind up to 80 mph. This tornado was part of a

radar-indicated circulation that began in Beaver County.

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.