Clear air turbulence forecasting has historically been a challenge. In recent years, many tools have been developed that have provided a measure of success. These tools can always be improved. This study focuses on one of these tools, Gary Ellrod's Turbulence Index (Ellrod Index), and attempts to determine if the index could be improved by the addition of other turbulence factors. The study began with the most recent version of the Ellrod Index and examined it in conjunction with Richardson Number, horizontal shear, stability gradient, and temperature gradient. The indices were then verified against 16pilot reports of turbulence over the north Pacific. None of the examined variables added significantly to the Ellrod Index, which performed at 75% accuracy. Four case studies were examined in additional detail to attempt to identify other potential turbulence drivers. It was ultimately determined that the Ellrod Index performs as well as can be determined by this study, the additional factors did not improve performance.