We analyse spiral bands and their strong convective clouds of tropical storm Vongfong during landfall by using hourly GMS infrared images.

The correlative synoptic system configuration and evolutionary characteristics of physical variables under longitudinal cloud band environment in Hainan Island s precipitation process are analyzed in the article, and it comes to some useful results.

Some conclusions are given as follows : If one or several long cloud bands of over 500 - 1000km length involve into the depression, and TBB decreases under -70℃ ℃ with the domain of - 60 ℃ isoline extending to more than 3 x 4 degree latitudes, the tropical depression would, very possibly, develop into .