1-Introduction One of the factors that affect the climate of arid and semi-arid areas is dust storm. Numerical models are new methods for evaluation of dust storms which can also be used for forecasting dust storms. The goal of this research was to utilize air mass back trajectory and mesoscale meteorological model analyses to investigate the wind patterns in Iran leading to synoptic-scale dust outbreaks impacting the west and center of this region. Back trajectories from a receptor site should assist in determining the air masses and dust transport patterns into the area of study to help better understand and forecast the formation and direction of motion of dust plumes. Synoptic-scale desert dust outbreaks are initiated by speciic weather conditions that depend on the nature and strength of large-scale wind systems over the region. Weather patterns that lead to dust outbreaks can be simulated using computer models that support a wide range of simulations related to the long-range transport, dispersion, and deposition of aerosols. Also, identify the source of infection is the first step in the process of determining an effective strategy for controlling pollution. One way to find the sources of pollution is back trajectory this means that the back trajectories from the receiver site can be used to specify the source locations. A coupling of meteorological and trajectory models is common method in studies of dust storms. In this study, we evaluated one off intense dust event that affected most of Iran. We used two numerical models, Weather Research and Forecasting (WRF) model and HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model…….