舟山2025年梅雨期内一次强对流过程诊断分析

Diagnostic Analysis of a Severe Convection Process during the Meiyu Period in Zhoushan in 2025

摘要: 2025年6月7日舟山市入梅，15日出现暴雨过程并伴随显著强对流，局地出现10~13级雷暴大风。本文基于探空资料、地面自动观测站资料的综合诊断表明：500 hPa舟山位于副热带高压北缘槽前西南急流区，700~850 hPa层存在切变线和显著暖湿平流，低层强盛西南急流和地面辐合促使暖湿空气快速抬升，是典型的“低层暖平流强迫类”强对流。探空显示CAPE值中等强度，但0~6 km风切变超过达到22.8 m/s，动力条件十分突出，同时中层强风速和相对干的空气为动量下传和冷池密度流的产生创造了条件。S波段、X波段雷达的监测资料展示了风暴的典型结构特征，包括飑线、弓状回波、低层大风区等。X波段雷达的剖面图及三维反演风场揭示了前期风暴中的悬垂结构、弱回波区、强上升气流，后期风暴的减弱、下沉气流。舟山立体风暴实时监控分析系统显示了强回波质心快速下沉、速度模糊区下沉，与极端大风实况相对应，说明大风是由下击暴流引起的。值得注意的是梅雨期在热力条件不显著的情况下，仍可能在强动力环境中产生破坏性大风，在短临监测预报中应特别关注中高层风速、垂直风切变、低层急流与切变线、对流风暴的悬垂结构、核心下沉以及速度模糊等信号。

Abstract: Zhoushan entered the Meiyu period on June 7, 2025, and a heavy rain event accompanied by significant severe convection occurred on the 15th, with local thunderstorm gales of magnitude 10~13. Based on a comprehensive diagnosis using sounding data and ground automatic weather station data, this study shows that at 500 hPa, Zhoushan was located in the southwest jet area ahead of the trough on the northern edge of the subtropical high. Shear lines and intense warm-wet advection existed at 700~850 hPa. The strong low-level southwest jet and surface convergence triggered rapid uplift of warm-wet air, representing a typical severe convection event forced by low-level warm advection. Soundings indicated moderate convective available potential energy (CAPE), while the 0~6 km vertical wind shear reached 22.8 m/s, suggesting extremely favorable dynamic conditions. Meanwhile, strong winds and relatively dry air in the middle layer provided conditions for momentum downward transport and the formation of cold pool density currents. Monitoring data from S-band and X-band radars revealed typical structural characteristics of the storm, including squall lines, bow echoes, and low-level gale regions. Cross-sections and three-dimensional retrieved wind fields from X-band radar illustrated the overhanging structure, weak echo region, and strong updrafts in the early stage of the storm, as well as the weakening and downdrafts in the later stage. The Zhoushan Three-Dimensional Storm Real-Time Monitoring and Analysis System captured the rapid descent of strong echo centroids and the sinking of velocity aliasing areas, corresponding well to the observed extreme gales, indicating that the gales were caused by downbursts. Notably, even under insignificant thermal conditions during the Meiyu period, destructive gales can still form in a strong dynamic environment. In short-term monitoring and forecasting, special attention should be paid to signals such as middle-upper-level winds, vertical wind shear, low-level jets and shear lines, overhanging structures of convective storms, core descent, and velocity aliasing.