Geophysical Research Letters — N° 2023 · 2025

Abstract Typhoon Haikui (2023) brought an unprecedented rainstorm to Fuzhou, with a rainfall record of 360.4 mm in 12 hr and an instantaneous rain rate of 234 mm hr−1. This study investigates the evolution of precipitation microphysics during this short‐term period. High rain rates exceeding 100 mm hr−1 along with large mass‐weighted diameter Dm were predominantly observed in the first 3 hr (Stage I), while the next 9 hr (Stage II) experienced less than 100 mm hr−1. At the onset of Stage I, it is warm‐cloud processes that mainly contributed to the increased rain rate, yet the rain rates hardly exceeded 200 mm hr−1. Approximately 1 hr later, a rain rate of 234 mm hr−1 occurred due to a joint contribution of ice‐ and warm‐cloud processes, characterized by the increased horizontal reflectivity throughout the troposphere. Moreover, this study provides a new insight into the correlation between rainfall intensity and convective intensity.