Cloud-to-Ground Lightning Characteristics of the Tornadic Storm over Hokkaido on November 7, 2006

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.