Vertical structure of the Tsukuba F3 tornado on 6 May 2012 as revealed by a polarimetric radar

The vertical structure of the 6 May 2012, Tsukuba F3 tornado which extended deep into the mid-level of its parent supercell was analyzed using data observed by the C-band solid-state polarimetric radar of the Meteorological Research Institute. The tornado was spawned at the tip of a hook echo and traveled 17km during its life time of 18 minutes. The radar observed the tornado vortex and its parent storm from about 15 km distance with volume scans that covered the height range between 0.1 to 4 km AGL. The vortex was identified as a region with high azimuthal shear. The analysis shows that the vortex had already extended to at least 4km AGL when the tornado started and the axis of the vortex was inclined at an angle of 45° from the vertical toward its direction of motion. Polarimetric analysis also shows that the altitude to which tornadic debris signature (TDS) reached gradually rose along the vortex with time.