Quasi-stationary Rossby waves, lasting weeks, can be linked to persistent extreme weather. The mechanisms of these quasi-stationary waves may be impacted by stationary forcings like topography, heating, and land surface. The presence of these forcings extends the duration of strong quasi-stationary wave events. Our climate model experiments give insights into the mechanisms of quasi-stationary waves, highlighting the importance of a combination of transient eddies and background flow conditions.