I flew there that day and the day after in a light VFR aircraft. Based on what I found, had they been a couple of thousand feet higher it would have been smooth.
That being said, it would have been a toss up between this:
forecast severe turbulence below 8,000 ft near and south of the ranges
And this:
occasional severe mountain wave turbulence in the area between 5,000 ft and FL140
Which one is worse?