Cyclonic and anticyclonic Rossby wave breaking (CWB and AWB, respectively) are identifiable by the overturning of large-scale atmospheric waves, particularly during the winter over the Euro-Atlantic region. CWB and AWB play crucial roles in modulating the passage of weather systems whose fluxes greatly impact the growth of persistent circulation patterns, or regimes. We quantify and diagnose the roles of CWB and AWB during the development of different circulation regimes using the ERA Interim Reanalysis as well as results from climate model simulations run at a range of horizontal resolutions. During development of a ridge of high pressure (often related to blocked flow), we find that despite a strong linkage with AWB, AWB-related fluxes actually work against ridge growth. We also find that the Equator-ward movement of relatively cold air near the Atlantic jet stream associated with AWB acts to support jet extension just as much as the horizontal shift of momentum. The representation and role of wave breaking is simulated quite well and not improved further by increasing resolution (grid mesh finer than about 60 km).