Statistics and Analysis on the Characteristics of the First Thunderstorm in Chongqing Airport in 20 Years

Based on the static analysis of first thunderstorms in Chongqing Airport during 1991²010, it shows that most of first thunderstorms occur in Mrch and April, and forecasters put more focus on mid-to-late March.They mostly occur from afternoon to after midnight, especially during the half of the night to dawn in next day.95% of first thunderstorms last less than 2 hours.Their intensity is weak, 80% of them are –TSRA or even only TS.Upper trough is the main synoptic system of generating first thunderstorms, and it occurs 18 times in 20 years.55% of first thunderstorms are created by upper trough and cold air mass.The radar reflectivity is between 55-60dbZ in PPI, and the RHI shows that the highest echo is basically under 11 km.In the satellite pictures, it is found that first thunderstorms frequently hide in the cloud system of upper trough or cold front.The convective characteristics of first thunderstorms are not obvious, which brings difficulties to forecasters.