In this paper, a new formulation of the Helmholtz equation for sound propagation in a moving inhomogeneous medium in cylindrical coordinates is derived. Based on this formulation, a novel three-dimensional parabolic equation is constructed. This parabolic equation can be used to model sound propagation in an inhomogeneous arbitrary moving medium. The method is used here to simulate three-dimensional outdoor sound propagation with an arbitrary wind above a rigid flat ground surface. The numerical results are presented and compared with benchmark analytical results to validate the methodology. Examples of propagation problems are then included, that demonstrate the importance of modeling the wind directly, rather than using an effective speed of sound.