A novel statistical model for over rooftop (ORT) propagation in an urban environment is presented in this paper. The proposed algorithm is based on an automatic extraction of the relevant environment parameters from the urban map. These parameters are used to build up a statistical description of the environment geometry through analytical pdf functions from which statistical estimates of the propagation loss are derived by mathematical processing and the use of simple, deterministic ORT models. Finally, analytical formulas for the direct derivation of the average ORT loss and its variance from the environment parameters are proposed