Analysis results of data from lidar and AWS observations performed in the northwestern part of the Taklimakan Desert show a sudden increase in the backscattering ratios in the lower troposphere on 13 April 2002, with strong easterly winds. The Terra satellite reveals that the sudden increase is caused by the outbreak of an extensive dust storm. Numerical simulations, using a regional model, reproduce the strong easterly winds prevailing in a wide area of the desert, originating from north of the Tienshan Mountains. These conclude that the strong easterly winds lift a large amount of sand particles off the ground and results in the dust storm. In addition, a nose-shaped profile of the increased backscattering ratios indicates passage of a gravity current.