Been through these mountain waves several times myself

[theking]

...as a regular flyer:

The most notoriously turbulent route due to mountain waves is Mendoza, Argentina (MDZ) to Santiago, Chile (SCL), crossing the Andes, followed by other South American routes like Córdoba (COR) to SCL, and U.S. routes over the Rockies, such as Denver (DEN) to Jackson Hole (JAC), and Albuquerque (ABQ) to DEN, all experiencing significant mountain wave effects, with China and the Himalayas also featuring prominently for severe turbulence.