Analysis of Hailstone and Thunderstorm Characteristics in Tianjin during Recent Years

Using hailstone and thunderstorm data from 13 meteorological observation stations, this article analyzes the spatial and temporal distribution characteristics of hailstones and thunderstorms in Tianjin and determines the routes of thunderstorm clouds and influence systems. The results showed that: (1) The annual mean number of hailstone-days was 12.6 d during the most recent 20 years, and Jixian district had the most hailstone-days. Hailstone weather often appeared in spring, summer, and autumn, and was concentrated from March to September. (2) The thunderstorm emergence probability was high from 1300 LST to 2000 LST. Those thunderclouds which emerged in the northwest and southwest had the highest frequency, with a total proportion of 65.2%. (3) The primary influence systems that could cause hailstones and thunderstorms in Tianjin were high-level vortices and upper troughs, with proportions of 49.54% and 43.12%, respectively.