Abstract:The synoptic situations, environmental physical parameters, and vortex signatures of a tornado process that occurred in Rizhao on 16 August 2019 are analyzed by using conventional observation data, data of densified regional automatic meteorological stations and Doppler weather radar, and NCEP/NCAR 1°×1° reanalysis data. The results are shown below. The meso-β scale convergence line and the northeast cold vortex are main synoptic systems, and the wet near-surface layer and low lifting condensation level provide favorable environmental conditions for the tornado. The meso-γ scale vortices on the ground convergence line trigger convections under significant deep wet convective potential, and the larger CAPE (convective available potential energy), stronger 0-3 km vertical wind shear are conducive to the development and merging of convective initiation, which eventually leads to the formation of the supercell storm. The hook echo and inflow notch appear on the right front of the lower layer of supercell storm when the tornado occurs. The main echo characteristics of the tornado are strong storm cell, deep and long-lasting mesocyclone, the strong center and bottom of the mesocyclone descending rapidly and coinciding, the cyclonic vortex being strengthened, the maximum wind shear increasing sharply, and tornadic vortex signature (TVS) appearing in many times of radar volume scan. The factors that play a dominant role in controlling the movement of tornado storm cells are different in different periods: the movement of early storms is mainly affected by advection; during the merging of storm cells, the movement is affected both by propagation and advection; after the storm cells completely merge, the steering flow plays an important role in controlling the movement of storm.