Precipitation Microphysics of Non-Tornadic Supercell Near the Radar Site of MRI in Tsukuba, Japan

A supercell with hook echo passed 2 km north of the Meteorological Research Institute (MRI) and was observed by the MRI advanced C-band solid state polarimetric radar (MACS-POL) on 12 August 2015 in Tsukuba, Japan. This storm had a wall cloud between the fore-flank downdraft (FFD) and the rear-flank downdraft (RFD). Although this storm did not accompany a tornado, PPI radar reflectivity sections showed a pair of small vortices (clockwise, counterclockwise) along the middle altitude of RFD and Zdr arc at the front of FFD. These phenomena are sometimes reported in tornadic supercells. We conducted dual-polarized RHI observations near the center of the mesocyclone including FFD and RFD and tried to interpret detailed microphysics. The cross-section of Zdr around the center of the mesocyclone suggested that the large raindrops over 6 mm were generated by convergence of inflow immediately at the center of the mesocyclone. These large drops had fallen at lower parts of the hook echo region along the rotation of the mesocyclone. In this presentation, the microphysical characteristics around the supercell and hook echo will be discussed.