National Weather Service United States Department of Commerce


A potent upper-level trough moved into the Great Lakes region on Thursday, October 21st, 2021, with an associated cold front moving east across the forecast area during the afternoon hours. A broken line of low-topped thunderstorms developed along the cold front during the early afternoon hours, moving into an environment characterized as low CAPE, high shear. Instability was very low with MLCAPE less than 500 J/kg. However, deep-layer shear was extremely favorable due to a belt of mid-level flow up to 60 knots. Storm relative helicity (SRH) was particularly favorable in the lowest levels with 0-500m SRH exceeding 100 m^2/s^2. As this broken line of storms moved into this environment, they began to show characteristics of low-topped supercells. These thunderstorms would go on to produce eight tornadoes across portions of northeast Ohio between 4:30 PM and 6:30 PM that afternoon, consisting of four EF-1’s and four EF-0’s.

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