EF0 tornado in Allegheny County, Pennsylvania

A team from the National Weather Service in Pittsburgh identified a coherent swath of likely tornadic damage that began along Stanton Ave in the Highland Park neighborhood of Pittsburgh and continued to along Campania Ave in the Lincoln-Lemington-Belmar area. Damage was sporadic along this path, suggesting the circulation occasionally weakened below tornadic intensity along this track, possibly owing to variability in terrain. The most concentrated damage was observed along Lemington Ave, where a couple trees were down, small and large limbs were snapped, and shingles were removed from homes. There is no evidence that power poles in this area were damaged by wind, which puts an effective upper bound on wind speed estimates here. Debris lofted by the tornado (likely leaves and small twigs) was noted in data from KPBZ radar, which continued in the air downstream for several miles as strong, non-tornadic wind surged eastward into the Penn Hills area. This narrow tornado was embedded within a broader swath of 40-60 mph non-tornadic wind, as evidenced by threshold tree litter. Pending additional information, this tornado will be rated EF0 with maximal wind of 70 mph.

Deep upper level low pressure moved into the western Great Lakes on November 20th. A strong shortwave rotating around this upper low across Ohio helped to drive a cold front across the Upper Ohio Valley during the late afternoon hours. A thin line of showers accompanied the front, with little to no lightning. The front worked with sufficient instability aloft to bring strong wind gusts to the surface, with several in the 45 to 60 MPH range according to various observations. These gusts were responsible for the many reports of wind damage received across southwest Pennsylvania. Strong low-level shear and weakly veered wind profiles also supported a brief tornado on the north side of Pittsburgh.