Interesting you got such mountain waves at FL300, blind pew. That was presumably a very long way below the trop? After our VC10 incident in the lea of the Andes in 1971 (even "accident", in terms of the substantial damage), BCAL realised that the mountain waves may be at their worst just below the tropopause. So on the EZE/SCL leg we flew at least 8000 ft below it, particularly if there was a big difference in the QNH between Mendoza and Santiago. IIRC, Swissair and KLM or Lufthansa had already sussed out the problem.
Safe flying in the rotors (rather you than me)...