Abstract: A strong convective gale occurred in Zhejiang Province on June 15, 2025. The maximum gust at the Yuxi Station in Shaoxing, Zhejiang, reached level 14 (41.7 m·s-1), the strongest gust ever recorded in Shaoxing since meteorological records began. The extreme gale was induced by a supercell within the severe storm. Based on multi-band radar data, this paper reveals the structural characteristics of the supercell and the causes of the extreme gale. The results show that: The supercell had a vortex pair structure, in which the main rotational flows of the mesocyclone and mesoanticyclone originated from the forward-flank warm and moist inflow and the mid-level rear-flank dry and cold inflow, respectively. Prior to the occurrence of extreme high winds, a cyclonic mesovortex existed in the mid-low levels, while the mesoanticyclone appeared only in the mid-levels. During extreme high winds, as the anticyclonic mesovortex extended downward, a vortex pair consisting of the mesocyclone and mesoanticyclone emerged in the low levels. The downward stretching of the mesoanticyclone was related to the downward extension of the rear inflow jet. Meanwhile, the increase and tilting of low-level horizontal vorticity into vertical vorticity caused by intense evaporative cooling also favored the development of low-level vortices. The intense evaporative cooling of hydrometeors induced by the downward extension of the rear inflow jet, together with the enhanced particle loading effect, accelerated the downdraft. Simultaneously. mid-level high-momentum air was transported to the near-surface layer within the downdraft, further amplifying the horizontal wind speed. All of These factors collectively lead to extreme high winds. The downward extension of the rear inflow jet to the low level might cause the wind direction at the station to reverse rapidly from easterly to westerly. Vertical stretching of the vortex pair, increased speed shear, and decreased shear height can all serve as precursor characteristics of the extreme gale. The base height of the mesoanticyclone was mostly higher than that of the mesocyclone. When the base of the mesoanticyclone stretched below 1 km, the extreme gale made landfall. The basin terrain played a crucial role in the extreme gale: The merging of the supercell"s front convergence zone with the basin"s airflow convergence center was conducive to storm development, strengthening both the front upward airflow and the rear downward airflow. Meanwhile, the superposition of the double basins and the channel effect further accelerates the wind speed at the station.