Abstract: Based on conventional observation data, NCEP 1° ×1° reanalysis data, two severe convective weather processes occurred in eastern Qinghai province from July 23 to 24, 2017 （referred to as “7.23”） and from July 31 to August 1, 2017 （referred to as “7.31”）were analyzed, and the characteristics of upper and lower environment field, dynamic, water vapor, thermal and convective instability conditions were compared. The results showed that the two severe convective weather processe occurred under the favorable background of large-scale circulation, and the main cause was that the surface cold air diffused southward from the Hexi Corridor and interacted with the southwest warm and humid air in the eastern part of Qinghai. The processes were triggered by dry tongue at 500 hPa, surface dew-point line, convergence line and surface cold front. Both processes were typical configurations of upper level divergence and lower level convergence, “7.31” was dominated by oblique ascending movement, and the water vapor convergence in the lower layer of “7.23” was stronger than that of “7.31”. There were two water vapor belts in the two processes, one was the water vapor belt carried by the southeast airflow on the west side of the subtropical high, and the other was the water vapor belt carried by the cold air in front of the upper trough. There was a high-value center of 350 K θse near 500 hPa, and a tilted intensive belt of θse near 38°N. This frontogenesis zone was more conducive to the development and maintenance of short-term heavy precipitation.

Key words: severe convective weather, temperature-humidity characteristic, unstable stratification, comparative analysis, Eastern Qinghai