Radar Echo Structures of Winter Thundercloud with Large Lightning Current Observed at Hokuriku Coast,Japan

Abstract

Two successive lightning strikes (over 200 kA) to the 200m-height stack were observed on December 21, 1995 during special observation period. The meteorological features of the thunderclouds, which caused the lightning strikes with large current, were revealed using weather radars, Doppler sodar and weather station data. The lightning strikes with large current were associated with the developing thunderclouds formed over the Japan Sea in cold air outbreak. A band-shaped radar echo with 100 km in length was developed near the coastline in meso-a.-scale low (cold vortex). The lightning strikes were observed twice at the top of the 200 m stack. The first strike occurred at the leading edge of the band-shaped echo (no echo region) at 0223 JST. After the landing of band echo cells, the second strike occurred in the core of the band system at 0234 JST. The mechanism of the large current lightning was involved that long term charge accumulation in the southwestern region of the band echo system, where is the formation area of new echo cells in its lifecycle, caused the lightning strikes with large current to the stack.