This research used enhanced observational data of dust concentrations, dynamic factors near the land surface, and vertical distributions of temperature and relative humidity collected from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), in combination with the NCEP FNL reanalysis data, to study a typical dust event that occurred in Lanzhou during March 2010. The goals are to reveal the background circulation, dynamic factors that caused the dust storm, and vertical profiles of meteorological variables. The results show that this dust event was caused by the interaction of a shortwave trough at high altitude and meso-scale depression system underneath this. Before the dust event, the instability of the low-altitude stratification with the assistance of temperature inversion at higher altitude provided the conditions for strong convection near the surface. During the dust event, the maximum PM10 concentration appeared shortly after the maximum wind, and the change in the meridional wind component was bigger than that in the zonal component. The temperature inversion was destroyed at higher altitude, and a significant humidity inversion occurred as a response. Relative humidity gradually decreased with altitude, and the rate of decline increased over time.