Based on conventional observation data from ground meteorological observation stations,sounding data,radar data,and NCEP 0.5°× 0.5° reanalysis data,forecast deviation and difficulties of the precipitation concentration period in Jiangxi and Fujian from June 28 to July 1,2021 were analyzed.The results showed that,1)This process presented large cumulative rain-fall and long duration.Extreme precipitation occurred in the northern section of Wuyi Mountains at the junction of Jiangxi and Fujian.The process can be divided into three stages:rainstorm in warm zone,multiple rain belts,and rainstorm in the south of warm shear.2)Jiangxi and Fujian Provinces were located in the upper level divergence zone on the north side of the South Asian high-pressure ridge,with obvious airflow diversion;The middle level zone was located behind a low trough at 500 hPa and small troughs were active;The low-level shear line was maintained along the Yangtze River.The north-south migration pace of main rainstorm over Jiangxi and Fujian was consistent with the shear line.Jet pulsations occurred many times in the south of the shear line,leading to changes in the wind speed convergence zone.The vortex and airflow ramp caused by the ter-rain near the northern section of Wuyi Mountains were conducive to the convergence and uplift of the boundary layer airflow and affected the rainfall.3)Finally,the Forecast focus of this kind of rainstorm is proposed.It is easy to trigger a strong convec-tive rainstorm if it is under the northwest air flow of the upper cold vortex,with hot and humid boundary layer.If the precipi-tation forecast of numerical models is systematic precipitation,the location can be adjusted to the bottom of the 500 hPa trough,the upper strong divergence,the top of the low-level jet stream and the top of the warm ridge in the south of the front area.At the same time,we need to pay attention to the trigger position of the mesoscale rain cluster and the impact of the changes in the upper and middle air flow.
关键词
强降水/暖区暴雨/回波特征/风速辐合
Key words
heavy rainfall/rainstorm in warm zone/radar echo characteristics/wind speed convergence
维普
万方数据