I went flying on Wednesday into what I thought would be a nice afternoon to putz around. The winds aloft were 10-15kts and generally all out of the north up to 9,000ft or so. The turbulence imagery forecasts on Garmin Pilot showed nil all the way into the flight levels and there wasn’t any active AIRMETs either. Needless to say, the flight was continuous light to moderate chop the whole time at every altitude I was at. So what gives? What causes this unstable, rough air that forecasts don’t seem to indicate?