In strong hurricanes, an outer ring of thunderstorms often forms that surrounds the main eyewall. This can "rob" energy from the inner eyewall, destroying it. The storm's maximum wind speed generally decreases while the wind field expands. A type of sudden structural change that's hard to predict

The outer ring then becomes the main eyewall. In a supportive environment, the hurricane then resumes intensifying after this process is complete. But there are usually differences which are sensitive to individual hurricane structure.