Mesoscale Analysis of Typhoon-Associated Tornado Outbreaks in Kyushu Island on 13 October 1980

Abstract

on 13 October 1980 five tornadoes occurred in association with typhoon 8019 WYNNE in the Miyazaki City area on the east coast of Kyushu Island, Japan, injuring 15 people, destroying about 400 houses and causing crop damage of sixteen hundred million yen. This tornado event was selected for study because of the availability of detailed surface data allowing for the examination of the mesoscale flow fields near the tornadoes. Emphasis is placed on the detection of the tornado cyclones and description of the tornadogenesis.
Around the time of the tornado outbreaks, there existed vertical wind shear of about 20ms-1 km-1 between the surface and 1km height, and saturated moist air with positive buoyancy prevailed over most of the troposphere.
The tornadoes occurred during the passage of west-northwestward to northwestward moving echoes in the rainbands of the typhoon. Four tornadoes originated from one long-lived echo.
Analysis of perturbation wind fields revealed that tornadoes occurred generally in the rear of the tornado cyclones which moved inland from the Hyuga-Nada at a speed of about 13ms-1.