Distributions of radar echo intensities (ZH) and differential reflectivity factors (ZDR) for ice particles in Japan's wintertime thunderclouds are investigating using C band dual polarization radar observations conducted on January 12, 1990, as a case study. At the moment of lightning strokes, the percentage of low-ZDR data points is increased around the cloud center, while that of high-ZDR data points is increased near the cloud edge. These radar echoes indicate the backscattering properties from graupel particles and ice crystals, both of which play a critical role in thunderstorm electrification. The ice crystal echoes are primarily enhanced 5--15 min before the lightning stroke. At the moment of lightning stroke; however, they are slightly decreased, and the graupel echoes gradually increase the intensity. These characteristics are well described by the convective motion of the dominant ice particles in this observational case. In addition, graupel echoes of more than 40 dBZ are found for these thunderclouds on January 12, whereas the clouds which produced no lightning, but indicated the evidence of comparable electrification, did not show more than 40 dBZ on January 18, 1990. The lightning locations are seen along the edge of the cloud center with ZH~30 dBZ, where graupel and ice crystal echoes distribute at short range. Their distributions are then estimated by counting both low- and high-ZDR data points on the constant altitude plan position indicator display, combined with their large and small echo intensities, respectively. Using polarimetric information (ZDR, ZH), the product numbers of graupel and ice crystal echoes in each 5¿5 km area are found to be fairly well correlated with the lightning location. These results are thus obtained for the one case of the present thunderstorm event, but they may give some insights on evolution of thunderclouds and lightning discharges. ¿ American Geophysical Union 1993