In intense storms greater than Category 3 it is normal for storms to undergo a concentric eyewall replacement. The outer eyewall robs moisture and heat from the inner eye wall which results in an increase in pressure and drop in winds; this process normally takes between 6 and 12 hours, upon completion the eye is bigger; but begins to contract and as it does so, the storm re-intensifies by using the theory referred to as the Conservation of Angular Momentum; like the water down a drain, as the circulation tightens, the particles - air and water increase in speed until two other forces act upon it as well - centripetal and centrifugal which all lead to the formation of the eye. In intense storms it is possible to have multiple eye walls. Hall and lightning are not as uncommon as you may think; remembering how tall these cells are at very, very cold temperatures in excess of negative 85. There is no known way to forecast intensity changes nor the predicatability of eyewall replacements with what is known today.