This report presents damages of houses and other structures caused by severe local storms which occurred on June 27, 2001 at Ichinomiya-shi in Aichi prefecture, on June 29, 2001 at Hokuryu-cho in Hokkaido prefecture, and on July 17, 2001 at Echigawa-cho in Shiga prefecture. According to the field studies, the damaged houses are distributed in a long and narrow region with 7-12km length and 200-600m width which correspond to P2 scale. The strength of the storms is estimated as F2 by the damage of houses. The damage of the roofing and roof systems are conspicuous. From the weather condition of each disaster illustrated by weather charts and images of GMS-5, the storms are caused by a local unstable atmospheric condition brought by a developing cumulonimbus cloud.

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Numerical simulation of the flow around a yawed circular cylinder with yaw angle 60° has been carried out under the same conditions as the previous visualization experiments. The calculated particle traces reproduce the observed streaklines of dye showing the three vortex pairs in the wake and the two horseshoe vortices around the upstream juncture. The computed vorticity shows that the sense of the rotation of the minor horseshoe vortex is opposite to that of the major horseshoe vortex. In addition to the previously observed horseshoe vortices, a vortex pair, which we identify as the juncture vortex, has been found very close to the upstream juncture. The juncture vortices stem from the side surface of the cylinder (around 30° from the windward) and connect with one of the wake vortex pairs.

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