Eyewall Replacement Cycle -- As strong hurricanes, typhoons, or cyclones intensify or hold steady, they can often replace the strongest region of winds and heaviest rains called the eyewall. This happens, usually in major hurricanes, when subsidence begins or intensifies outside of the eyewall OR a stronger band of storms forms outside of the main eyewall and feeds into the center of the system. Generally the effect is a weakening of the system at least temporarily. The hurricane also usually expands during this process. Cycles typically last 12-18 hours including the contraction process. The inner eyewall may dissipated in less than 12 hours after the outer eyewall forms.
Eye on Weather 
Sitting on Long Island in the Southeast Bahamas, typing “N” is the first thing I do in the morning (National Hurricane Center comes up).
Your discussions are interesting, informative, and full of much more information than I know. Thank you!
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