Analysis and application of various observational data in a heavy precipitation in Dali of Yunnan province

Unconventional observation data,such as data of the newly built Generation Weather Radar(the CINRAD/CC) in Dali, the wind profile radar, ground intensive automatically observation station and lightning position finder,are used to analyze the heavy precipitation event occurred from the night of 27 July to the day of 28 July 2012 in Dali, Yunnan Province. It is shown that the main impact factors to the event are the inverted trough in 500 hPa and low-pressure vortex in 700 hPa. The evolution of heavy precipitation event can be divided into three stages. In the formation stage, precipitation mainly appears as convective precipitation; rainfall intensity is strong, but precipitation cells are isolated and short lived. Thunder and lightning are observed in most of the Dali area. In the maintenance phase, lightning activity significantly reduced, and radar echo is dominated by stratiform cloud precipitation echo, which does not exceed 35 dBz. In the maintenance phase, the characteristics of radar radial velocity field are the superposition of warm advection and convergence wind field. Counter-wind zone appears both in the formation and maintenance stages with the differences in coverage and duration. Precipitation is significant nearby and along the path of the Counter-wind zone. In the dissipating stage, echo coverage decreases, and its intensity weakens. From the radial velocity, it is seen that the northeast airflow controls entire layer in radar detectable area. Divergence and vertical velocity calculated by EVAD can well reflect the dynamic process of the heavy precipitation, these are good indications to the precipitation enhancement and maintenance. These is a close relationship between negative vertical velocity and precipitation intensity from analysis of the wind profiler radar products. The signal to noise ratio can well indicate the beginning and the end of precipitation, and to its increase or decrease in intensity. The precipitation increase was closely related to the momentum transportation downward caused by greater than 8 m·s-1northerly air-stream.