Sandbar migration, driven by complex interactions with nearshore hydrodynamics, remains a challenge for coastal modelers despite its critical role in dissipating incident wave energy. This manuscript aims at showing the ability of the 3D model CROCO, in its phase averaged mode, to predict the cross-shore sandbar migration of a natural beach by solely depending on the wave conditions. The model benefits from the recently implemented and adapted SANTOSS formulation to compute bedload sediment transport induced by shoaling wave asymmetry. Simulations are validated using datasets from the Duck94 campaign, which capture the hydrodynamics and morphological changes of a barred beach in Duck, NC, USA. The model accurately reproduces observed onshore and offshore sandbar migration by varying only the wave forcing conditions - same model parameters are used for both cases -, achieving Brier Skill Scores (BSS) of 0.69 and 0.74, respectively. Future work will extend the model alongshore to include 3D processes in the sediment transport, enabling the simulation of sandbar migration in both cross-shore and alongshore dimensions.