Atmospheric Gravity Waves (AGWs) frequently occur around near coastal offshore wind farms. Yet our understanding of how they interact with individual turbines and whole farm energy output is limited. This research uses computational fluid dynamics modelling to investigate the impact of near coastal, topographically forced AGWs on offshore wind farm power output in a theoretical wind farm. Preliminary results show the farm contained within one wavelength (4.9km) of the topographically forced AGW. The AGW causes a substantial variation in wind speed across the farm with a subsequent 76% variation in power output compared to 29% in the control case. @en