Our approach was from the south and we flew over Utah Lake. The plane began to say, bump, and drop suddenly. There was one time that the stewardesses all fell to the floor and grabbed onto the seat around them.
This is the MODIS image for the day I flew into Salt Lake City on June 14, 2014. There is evidence of wave like structure in the clouds on that day...
The sounding appears to have the ingredients of a mountain wave--stable air at mountain peak and cross mountain winds with winds from the west.
Here is a view from the plane and from near the airport after landing. Kind of hard to determine if there were mountain waves.