黄石地区一次局地特大暴雨天气过程分析

Analysis of a Local Extremely Heavy Rainstorm Weather Process in Huangshi Area

摘要: 利用MICAPS常规气象观测资料、多普勒雷达和气象卫星等，对2023年7月21~22日黄石地区出现的一次局地特大暴雨天气过程进行诊断分析。结果表明，(1) 此次过程是在200 hPa南压高压、高空槽东移、冷空气与副高北侧偏西气流交汇的共同影响下产生的；降水前高温高湿，降水过程中西南气流辐合加强，强降水时段700 hPa、850 hPa、925 hPa的切变线位置高度重合是形成此次局地特大暴雨的主要原因；(2) 各家数值模式对强降水的中心位置及强度预报均存在明显偏差，尤其是降水中心强度较实况显著偏弱，主要源于各个模式预报的高空槽偏浅、高空槽和副高位置有偏差、西南气流偏弱、200 hPa南亚高压强度偏弱及鄂东南风向风速的辐合区漏报等；(3) 对于副高北侧有明显低槽东移导致的降水，如果有相对较长的持续时间，预报员应重点关注模式对此类形势下西南气流强度和低层辐合的预报能力，在预报服务时可以尝试提高降水量级，并加强短临预报服务，值班时结合实时观测资料审慎评估其降水预报偏弱的风险，及时发布预警信号与临灾警报。

Abstract: By using MICAPS conventional meteorological observation data, Doppler radar and meteorological satellites, etc., a local extremely heavy rainstorm weather process that occurred in the Huangshi area on July 21~22, 2023 was diagnosed and analyzed. The results show that: (1) This process was generated under the combined influence of the 200 hPa southward high pressure, the eastward movement of the upper-level trough, and the convergence of cold air and the west-facing airflow on the north side of the subtropical high. The high temperature and humidity before the precipitation, the strengthening of the convergence of the southwest airflow during the precipitation process, and the high overlap of the shear line positions at 700 hPa, 850 hPa and 925 hPa during the heavy precipitation period are the main reasons for the formation of this local extremely heavy rainstorm. (2) There are significant deviations in the predictions of the center position and intensity of heavy precipitation by various numerical models. Particularly, the intensity of the precipitation center is significantly weaker than the actual situation. This is mainly due to reasons such as the shallower upper-level trough predicted by each model, the deviation in the position of the upper-level trough and the subtropical high, the weaker southwest airflow, the weaker intensity of the 200 hpa South Asian high pressure, and the underreporting of the convergence zone of the wind direction and speed in the southeast of Hubei. (3) For precipitation caused by a significant eastward movement of a trough on the north side of the subtropical high, if it lasts for a relatively long time, Forecasters should pay close attention to the forecasting capacity of the model for the intensity of the southwest airflow and the low-level convergence under such circumstances. When providing forecasting services, they can attempt to increase the precipitation level and enhance short-term and immediate forecasting services. During their duty, they should carefully assess the risk of weak precipitation forecasts based on real-time observation data and promptly issue early warning signals and disaster alerts.