Cloud-to-Ground Lightning Features of Tornadic Storms Occurred in Kanto, Japan, on May 6, 2012

The features of parent clouds of tornadoes generated in north Kanto, the middle of Honshu, on May 6, 2012 are discussed from the viewpoint of CG lightning. Cumulonimbus clouds (radar echo cells) that caused tornadoes had a peak lightning frequency of 20 strikes/min before the tornado generation. The number of lightning strikes decreased and positive lightning increased during the tornado generation. Cells that generated tornadoes were frequent lightning cells among echo cells generated around Kanto on that day, and long-landing and high-frequency lightning cells included mesocyclones in the clouds. The features of cumulonimbus with the potential to generate tornadoes are clarified.