X-band dual-polarization (multi-parameter) radars observed the supercell storm that generated an F3 tornado in Ibaraki Prefecture, Japan on 6 May 2012. The observational data collected for the storm clearly show typical polarimetric features of a supercell storm, such as the ZDR (differential reflectivity) arc, ZDR column, and K DP (specific differential phase) column, and their time evolution. The ZDR arc emerged 10 or 15 min before tornadogenesis. The ZDR column appeared about 1 hour before ZDR arc formation and developed intermittently until tornadogenesis. Just when the ZDR arc appeared, the column was becoming taller and stable, and lasted until the dissipation of the tornado. These ZDR signatures of the supercell storm lasted around half an hour.
2017 by Meteorological Society of Japan