At noon on April 20, 2006, a wind storm occurred in Fujisawa City, Kanagawa Prefecture, Japan with a F0-P1-P1 rank on the Fujita-Pearson-scale (FPP-scale). Damage to over 40 residential buildings was observed. The damage covered an area 2 km by 50 m. The strong winds were accompanied by the passage of a cold front. Eyewitness accounts of a dust column and the recording of a pressure drop (1.5 hPa) indicate the existence of a tornado vortex. A hook-shaped radar echo (5 km in diameter) was observed in the narrow cold frontal rainband, with strong horizontal wind shear above the damage area. The Doppler velocity pattern indicated a misocyclone, which had a diameter of 2 km and a vorticity on the order of 10 2 s 1 . The wind storm may have caused the tornado, which formed in the cold frontal wind shear zone.
On May 31, 2007, a waterspout occurred over Tokyo Bay near the Futtsu Coast, Chiba Prefecture, Japan. Based on Doppler radar observations and the field surveys, the detailed structures of the funnel and the parent cloud were revealed. The funnel diameter was about 25 m near the surface, and expanded as the altitude increased. The misocyclone had a diameter of 0.2 km and vorticity on the order of 10 1 s 1 below the cloud base. The lifetime of the funnel was about 7 minutes, while that of misocyclone was about 20 minutes. The waterspout formed over the wind shear zone, which was favorable for the formation of an anticyclonic vortex.
Five misocyclones occurring along a narrow cold frontal rainband (NCFR) were detected by single, X-band Doppler radar at Yokosuka, Japan on April 20, 2006. Each of the misocyclones, which formed in succession in the core and gap regions of the meandering NCFR over a period of 30 minutes, had a short lifetime. Three of the five misocyclones generated near the surface and reached altitudes of up to 4 km ASL. The diameters of the lower-level misocyclones increased with altitude and vorticity in the order of 10 À2 s À1 was observed near the surface. Two of the five misocyclones had similar diameters and vorticity, and at more than 6 km ASL. One of the observed misocyclones was related to the tornado in Fujisawa and as a non-supercell type tornado within the NCFR. This tornado-related misocyclone had the largest vorticity (5 Â 10 À2 s À1 ) near the surface (300 m ASL) and was characterized as having the reduced diameter below the cloud base, which is considered typical of a tornado.
Abstract. The relationship between the evolution of the tornadic storm and the cloud-to-ground (CG) activity was investigated on the F3 tornado event in Saroma-cho, Hokkaido on 7 November 2006. The echo system which caused tornadoes in Saroma-cho was the mesoscale convective system (MCS) having both the convective core region and the stratiform region. CG lightning was active in the decaying stage of the MCS. Most CG lightning was negative and occurred around a relatively strong echo area in the stratiform region of the MCS. The MCS had two peaks of the CG lightning activity at the developing and decaying stages. The Saroma tornado occurred at the decaying stage of the system when the concentration of CG frequency was observed.
, wind disaster occurred in Fujisawa City, Kanagawa Prefecture. We surveyed the characteristics of this disaster during two days. Damage to over 40 residential buildings was observed and damage area extended a line of 2 km by 50 m. According to the feature of damage, we presumed that Fujita-Pearson-scale (FPP-scale) was F0-P1-P1. The reasons why the gust in the area was a tornado were as follows. 1) The damaged area lies in a narrow line. 2) Indication of rotatory (cyclonic) wind was observed.3) The vortex with 2 km in diameter (misocyclone) was observed by a Doppler radar. 4) Pressure drop of 1.5 hPa was recorded near the damage area. The wind disaster in Fujisawa was caused by a tornado, which formed in a narrow cold frontal rainband.
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