Utilizing composite groups created according to the RI onset times of the members, it is shown that for increasing magnitudes of deep-layer vertical wind shear, RI onset is increasingly delayed. In addition, a critical shear threshold appears to exist in which the TC will not intensify once it is exceeded. Although the timing of RI varies by as much as 48-h, a decrease in wind shear is observed across the intensifying composite groups approximately 1224 h prior to RI. This decrease in wind shear is accompanied by a reduction in the magnitude of the tilt of the vortex, as the precession and subsequent alignment process begins approximately 2448 h prior to RI. Sensitivity experiments reveal that some of the variation in RI time can be attributed to the initial intensity of the vortex, as the earliest developers intensify regardless of their environment. In addition, the non-developing members fail to undergo RI because of a less conducive environment, although significant sensitivity exists in which very small differences in dynamic and thermodynamic fields produce divergent forecasts. Using HS3 dropsondes, as well as the PSU WRF-EnKF ensemble simulations, the thermodynamic structure of Edouard is also being examined. Temperature profiles are calculated from both environmental and inner-core observations, with particular attention paid to the vertical structure and time evolution of the warm core leading up to RI onset, throughout RI and once peak intensity has been reached.