Accurate turbulence modeling is an essential prerequisite for the use of Computational Fluid Dynamics (CFD) in Wind Engineering. At present the most popular turbulence model for general engineering flow problems is the ${kappa}-{varepsilon}$ model. Models such as this are based on the isotropic eddy viscosity concept and have well documented shortcomings (Murakami et al. 1993) for flows encountered in Wind Engineering. This paper presents an objective assessment of several available alternative models. The CFD results for the flow around a full-scale (6 m) three-dimensional surface mounted cube in an atmospheric boundary layer are compared with recently obtained data. Cube orientations normal and skewed at $45^{circ}$ to the incident wind have been analysed at Reynolds at Reynolds number of greater than $10^6$. In addition to turbulence modeling other aspects of the CFD procedure are analysed and their effects are discussed.