Abstract:Two tornado processesoccurred in Xuzhou City, Jiangsu Province from 18:00 BST to 20∶00 BST on August 18, 2018. The duration of both two cases is about 1min, and the intensity is EF1-EF2. The location of the second tornado is far from the radar station, so only the first onewas analyzed. The analysis of conventional observation data and Xuzhou Doppler weather radar data shows that: before the tornado, the thunderstorm finally produce a tornado was after it strengthened twice, which indicates that the reinforcement of convective monomer is beneficial to induce tornado. The unstable environmental condition of upper dry and lower wet,strong vertical wind shear in the mid-low layers and low uplift condensation height provide favorable conditions for the generation of tornadoes. The radar reflectivity factor presents super-cell characteristics and the hook echo. In the 18 minutes before the tornado occur, a mesocyclone is detected in the radar echo map and maintains four scans with a obvious trend from high to low level. At the lowest elevation, a strong velocity shear between adjacent pixels is detected, which provides a good reference for the early forecasting of tornado.