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.