During the warm season (June-September) from 2014 to 2018, the sounding parameters and indices of convention as well as the spatial characteristics and distributions of the afternoon convective storms in Shanghai under weak synoptic-scale forcing were documented using atmospheric sounding data, storm tracking identification (STI) and storm structure (SS) products. The STI product provides storms’ current position and the historical position. Intending to reveal the trigger mechanism in Shanghai under weak synoptic-scale forcing, storm frequency statistics in different regions were made utilizing the storm position firstly, then the spatial distribution of storm track was analyzed based on storm historical position. The convective storms in afternoon were classified into three types including storm from other places, localized moving storm and localized anchoring storm according to storm position and historical routes. The corresponding storm structure was introduced to reveal the differences of storm life cycle as well as the storm structure characters. The results show that the afternoon convective storms that affect Shanghai in warm season mainly occur in the region from urban to the Yangtze River Estuary, which is mainly due to the urban heat island effect and the northern sea breeze. There are significant differences among the three types storms in life cycle, centroid height, vertical integral liquid, maximum reflectivity and height of maximum reflectivity.