Classic wave is typically assumed to form downwind of high terrain, but here at Crystal we sometimes see the process operating in reverse.  When strong wind flows over flat country against a large, uniform slope perpendicular to it, ordinary slope lift may or may not be present on the mountain itself, but above and upwind of there a large, smooth wavelike flow could be present.  It may not flow thousands of feet higher than the slopes, but may propagate into the wind like conventional harmonic waves in reverse!