We have the thermals/updrafts from ground up to the cloudbase that should be laminar flow(predictable). Whats missing is the air that mixes inside clouds that makes the airflow turbulent (unpredictable). Thunderstormclouds for example are dangerous because the high velocity in air that makes the air even more turbulent (unpredictable). The higher velocity (the higher the cloud is) in air the more turbulent flow. Same for the air closer to ground that are affected by the friction layer. Friction creates mixing of air as well. That thing we have simulated by those gusts and terrain that creates those up and downdrafts near ground. Same thing near ground, the higher velocity of airflow the more turbulent flow.
The mixing of air inside clouds we want added 
Also CAT is missing (mixing of air at higher altitudes) More noticable now when they reduced the height of the turbulence caused by mountains