It is common for strong and powerful storms to undergo eyewall replacements, which allow for a brief period of weakening, like we saw with Milton going from a Category 5 to a Category 4 early Tuesday.
As hurricanes strengthen, the eyewalls, which consist of "a ring of tall thunderstorms that produce heavy rains and usually the strongest winds," according to NOAA, become tighter and more intense until they reach maximum strength in their environment.
A new eyewall may then begin to form on the outside of the previous inner eyewall, which cuts off the energy for the intense inner eyewall. This causes it to collapse and weaken.
Tuesday begins with #Milton having completed it's eyewall replacement cycle. The new eye is clearing out and the wind field has expanded. An expanding wind field, the angle of approach to the coast, and the formidable strength, all will lead to a deep & damaging surge in #Florida pic.twitter.com/hfNzf2vUUr
— John Morales (@JohnMoralesTV) October 8, 2024
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As the outer eyewall regains organization, the storm will often re-increase in intensity.
This can take several hours (around 12 to 18) to complete.
The forecast models have extreme difficulty with predicting an eyewall replacement cycle.
Although an eyewall replacement cycle can reduce the category of a hurricane, we can also experience the expansion of the wind field. This means the hurricane force winds and tropical storm force winds begin to reach out over a larger area.
We are expected to see an expansion of the wind field as this weakens and approaches Florida.
But don’t forget: it will still be a major and dangerous storm at landfall.