Desert185,
I knew where Minden was, but I had to look for Ely on GE. I see that the maximum elevations on that route are about 7000'.
I have often found in good wave conditions in southern Alberta, or when arriving or departing from Salt Lake in commercial jets, that it can be very smooth with little or no turbulence above the local ridge lines, but very rough below them.
I'm not sufficiently up on the physics of waves to know what causes those conditions, but you must have had the right conditions on that trip. Did the turbulence start below the ridge top elevations?