ANALYSIS ON THE CAUSES AND FORECAST BIAS OF RAINSTORM PROCESS IN QIUBEI"May 27"
Affected by the shear line and the southwest warm and humid airflow,a heavy precipitation weather process occurred in Qiubei County,Wenshan Prefecture from May 26 to 27,2022.The process had the obvious characteristics of large precipitation range,long duration and strong short-term rain,resulting in severe flash floods and debris flows in Qiubei County.The analysis results show that:during the rainstorm,Qiubei County maintained a strong upward movement directly to the troposphere for a long time,and the period of the strongest upward movement corresponded to the period of heavy rainfall;at the same time,the southwest airflow from the Bay of Bengal and the southerly airflow from the Beibu Gulf jointly transported water vapor to Qiubei County,Wenshan Prefecture.The strong convergence area of water vapor flux coincided with the 700 hPa shear line and the ground cold front position;the two cooperated with each other to provide good power and water vapor conditions for the large-scale rainstorm.During the heaviest rainfall period,the convective cloud clusters over the northern part of the mountain gradually developed and formed MαCS,with obvious upward cloud tops;the radar echo top height increased to more than 20 km,the centroid intensity was greater than 65 dBZ,the centroid height contin-ued to drop below 5 km,and the cyclonic convergence was maintained for a long time on the velocity map.The main reason for the deviation of the forecast is that the model does not reflect the 500 hPa short-wave trough and the 700 hPa shear line.
NETL
NSTL
万方数据
