GUST FRONTS OBSERVED WHEN THE WIND DISASTER OCCURRED IN SAKATA CITY 2 DECEMBER 2007

Abstract

When the tornado damaged Sakata city about 1:30JST of 2 December 2007, some gust fronts were observed by the X-band Doppler radar and the array of supersonic anemometers along the Mogami river Daini bridge. The first two peaks of gusty wind were not accompanied by any apparent echo patterns. The following two peaks occurred with bow echoes. They have relatively short life time of about 10 minutes and showed the velocity change yielded by the passage of the gust front. The horizontal distribution of the gust front was not uniform, which showed that there were small scale structures in the gust front.