摘要
Based on the conventional observational data, NCEP, satellite and radar data, the weather diagnosis and mesoscale analysis of the first rainstorm appearing in Shaoyang City since the flood season from June 14 to 15 in 2011 were carried out. The results showed that this rainstorm occurring in the whole Shaoyang City was an typical rainstorm during the first rainy season, and resulted from the strong development of the mesoscale system generated under extremely favorable weather situation. Guided by the cold advection behind the East Asia trough at 500 hPa, cold air moved southward and met southwest airflow in the northwest of strong subtropical high, so that the junction zone of clod and warm airflow was kept in the middle of Hunan Province. In addition, the stable junction zone of clod and warm airflow as well as extremely vigorous southwest warm and wet airflow made the rainstorm have adequate water vapor, dynamic and thermal conditions, which was extremely beneficial to the stong development of small and medium-scale convection systems. In a word, due to stong water vapor and convergence upward movement, reinforcement of low-level southwest jet, activity of low-level weak cold air, exacerbation of convective unstable stratification, superposition of strong divergence at high levels, and obvious development of vertical vorticity caused by vertical shear of horizontal wind or increase of moist baroclinicity, the rainstorm happened in Shaoyang City.
Based on the conventional observational data, NCEP, satellite and radar data, the weather diagnosis and mesoscale analysis of the first rainstorm appearing in Shaoyang City since the flood season from June 14 to 15 in 2011 were carried out. The results showed that this rainstorm occurring in the whole Shaoyang City was an typical rainstorm during the first rainy season, and resulted from the strong development of the mesoscale system generated under extremely favorable weather situation. Guided by the cold advection behind the East Asia trough at 500 hPa, cold air moved southward and met southwest airflow in the northwest of strong subtropical high, so that the junction zone of clod and warm airflow was kept in the middle of Hunan Province. In addition, the stable junction zone of clod and warm airflow as well as extremely vigorous southwest warm and wet airflow made the rainstorm have adequate water vapor, dynamic and thermal conditions, which was extremely beneficial to the stong development of small and medium-scale convection systems. In a word, due to stong water vapor and convergence upward movement, reinforcement of low-level southwest jet, activity of low-level weak cold air, exacerbation of convective unstable stratification, superposition of strong divergence at high levels, and obvious development of vertical vorticity caused by vertical shear of horizontal wind or increase of moist baroclinicity, the rainstorm happened in Shaoyang City.
