The key physical processes responsible for inner-core structural changes and associated fluctuations in the intensification rate for high-impact tropical cyclones that underwent rapid intensification are investigated using convection-permitting ensemble simulations. Fluctuations in the inner-core structure between ringlike and monopole states develop in the majority of simulations for two selected storms. We will use the tangential momentum budget analysis to study the transition between both phases as the storms intensify. During the ringlike phase, the tangential wind generally intensifies, whereas during the monopole phase, the tangential wind remains mostly constant. Our results strongly indicate that to fully understand the storm’s three-dimensional evolution, the contribution of the eddies must be quantified.