Abstract:Tornadoes occurred in front of typhoon in Jiangsu Province on 29 to 30 July, 200 8. A detailed analysis of the environmental conditions, structure and evolution of tornado is made based on the Doppler weather radar data, routine upper air a nd surface observations, and intensive automatic weather station observations. T he main results are as follows: The tornadoes occurred in the area with high val ue of low level vertical wind shear. The low lifting condensation level, unstabl e stratification and deeper positive vorticity all these factors supplied the th ermodynamic and dynamical conditions for the occurrence of tornadoes. The tornad o occurred at Dongtai is associated with a mesoscale squall line, whereas the t ornadoes occurred at Gaoyou and Baoying are associated with multi cell convective storm. The rear part of the storm cell ha s a large reflectivity gradient, which is often accompanied by the weak echo str ucture and back flank notch in the low level. Not all the tornadoes occurred i n the storm cell with meso cyclone and tornado vortex signature. Some tornadoe s happened in the storm cell with weak cyclone vortex in the low level. When th e altitude of strong echo center and the vertical cumulative liquid water falls suddenly and cyclone vortex develops rapidly, the tornado will occur very soon. In operational work, we shouldn’t alert the occurrence of tornadoes only de pending on the meso cyclone signature and tornado vortex signature. We should a lso combine the other products, for example, reflectivity, average radial vel ocity, storm structure, etc. It is possible to greatly enhance weather radar’s capability to detect the tornadoes.