In recent years, some experiences of forecasting torrential rain and severe convective weather are acquired by comprehensive analysis of observational data from satellite,radar and ground surface. Yao Zuqing,XiaoWenan et al. predicted torrential rain and severe convective weather over the middle and lower reaches of the Changjiang River by tracking cloud cluster activities in terms of the satellite cloud pictures and summing up the features of five types of environmental cloud fields affecting the torrential rain and severe convective weather there and the evolution processes of these cloud clusters. Du Bingyu et al. designed a nowcasting system for predicting the torrential rain over the Three Gorges of the Changjiang River and the Jingjiang area by using mainly the radar data. In this paper, the signs of the weather element fields and the physical quantity fields affecting the three torrential rain and tornado weather processes occurring in Shanghai on September 3,1983,July 11,1985 and July 26,1983 are examined based on the data from the densely spaced ground observing stations in Shanghai,with a prospect of providing a sound criterion for the prediction of torrential rain and severe convective weather by analyzing the variational features of the surface observational data.