Deep inside a hurricane, the fiercest part of the storm — the eyewall —can be quietly choked out and replaced.

This is called an eyewall replacement cycle, and it comes with a major trade-off.

The storm's peak wind speed falls temporarily, but the entire wind field expands, causing even more widespread impacts. Here's what you need to know:

Q: What is an eyewall replacement cycle?

It's the process by which a strong hurricane grows a second, larger eyewall outside its original one — and that new outer ring gradually strangles and then replaces the inner one. This new eye makes more room for convection and energy, which can spread the hurricane-force winds over a larger area.

These cycles occur when the original eyewall can't maintain its structure. This can happen when the eye becomes too small or winds become too strong. This leads to the eyewall breaking down. 

(MORE: Why the eyewall is the most intense part of a storm)

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Q: What are the phases?

1. Intensification: The outer eyewall develops while the inner eyewall contracts inward and the storm strengthens.

2. Weakening: The inner eyewall's strengthening stalls as the outer ring cuts off its fuel. The storm increases in size in this phase. 

3. Re-intensification: The new outer eyewall consolidates and the storm strengthens again, sometimes dramatically. This phase often carries a storm to its lifetime peak intensity.

Q: Why does the storm weaken during the cycle?

The storm weakens because the two eyewalls are competing for the same fuel. The outer ring intercepts the warm, moist air that the inner eyewall needs, cutting off its energy supply. Since the strongest winds live in the eyewall, choking the inner one drags the storm's peak intensity down with it, temporarily.

(MORE: Hurricane terms you should know)

Q: How common are these cycles?

Eyewall replacement cycles are common among intense hurricanes and can happen multiple times to one storm. These often occur in Category 4 or 5 hurricanes. 

Q: Why do they make forecasting so hard?

The timing of eyewall replacement cycles is challenging for forecast models to predict. The weakening of the storm followed by the often dramatic re-intensification makes intensity forecasting difficult as well. 

Caitlin Kaiser graduated from the Georgia Institute of Technology with both an undergraduate and graduate degree in Earth and Atmospheric Sciences before starting her career as a digital meteorologist with weather.com.