Evolution of a Tornado and Debris Ball Associated With Super Typhoon Hagibis 2019 Observed by X‐Band Phased Array Weather Radar in Japan

Abstract A tornado associated with category 5 Super Typhoon Hagibis occurred on October 12, 2019 in Ichihara City, Chiba Prefecture, Japan. An X‐band phased array weather radar revealed the occurrence of the tornado at the south edge of its parent cloud, which had several characteristics of a classic supercell (mesocyclone, hook‐shaped echo, bounded weak echo region, and vault shape). Phased array radar observation also revealed a three‐dimensional multiscale structure of the tornado with a mesocyclone and misocyclone at different altitudes. The misocyclone, the vorticity of which intensified for several minutes under the mesocyclone, resulted in the formation of a tornado and debris ball. The echo top height of the debris ball abruptly increased at the time when the vorticity of the misocyclone maximized at low levels, suggesting a rapid evolution of tornadic vortex and the associated damage on the ground.