Bigger or stronger? How winds will shape Hurricane Milton on Tuesday.

To use a fairy tale comparison, the potentially catastrophic Hurricane Milton could face the weather equivalent of the big, bad wolf as it approaches Florida — wind shear.

That interaction could bring mixed blessings. The strength of the storm, its wind speeds and the breadth of its storm surge all will depend on whether winds blowing over the Gulf of Mexico will be strong enough to blow its house (structure) down.

If the winds Milton encounters as it approach Florida are strong enough to disrupt its inner core, the storm's most intense winds could weaken a little, said James Franklin, a retired branch chief for the hurricane specialists at the National Hurricane Center. At the same time, the hurricane could grow in size and push more water onto shore in a surge of seawater, Franklin said.

Either way Milton is forecast to be a dangerous and powerful storm.

How do hurricanes form?An inside look at the birth and power of ferocious storms

How does a hurricane work?

A hurricane in its essence is a heat engine, Franklin told USA TODAY on Monday. "It extracts heat from the ocean and the heat gets released in thunderstorms around the eye. Additionally, air moving downward in the eye creates heat as it sinks."

“You have all this heat being released and generated in and around the eye in a fairly tight vertical column,” he said. That heat lowers the pressure and “keeps the engine going," allowing the hurricane to flourish and grow.

How could wind shear help or hurt?

Wind shear occurs when winds in the storm's vicinity collide with winds blowing at different speeds or directions.

If those winds disrupt or shift the heat release from a hurricane's relatively small vertical column and spread it out over a larger area, the pressure stops falling in that inner core, Franklin said. When the wind shear is strong enough, "it’s essentially blowing the top off the hurricane and you no longer have an effective heat engine."

Low wind shear is a hurricane enabler

Milton’s explosive increases in wind speed and intensity and drops in pressure Monday were a classic example of how a hurricane works in a low wind-shear environment.

Moving over very deep, warm waters with a low wind shear, the wind speeds grew by 85 mph in just 12 hours, according to hurricane center data, and the pressure dropped by an astonishing 64 millibars. (Lower air pressure typically means higher intensity and winds.) That makes it one of the lowest pressure storms in modern history in the Gulf of Mexico.

Low wind shear allowed the heat to concentrate so the pressure could fall, Franklin said.

Since 1979, only three hurricanes in the Gulf of Mexico have had lower pressure than Milton on Monday, said Phil Klotzbach, a senior research scientist at Colorado State University. Those storms were Allen in 1980; Katrina in 2005 and Rita in 2005.

Size matters for hurricane intensity

Small storms like Milton can make the fastest increases in intensity, Franklin said. “But they can also come down the fastest, because smaller storms don’t have the same resiliency to wind shear.”

Starting Tuesday, forecasters expect Milton's intensity to be dictated by eyewall replacement cycles, which could cause the system to gradually weaken but grow larger, wrote Eric Blake, one of the center's hurricane specialists, in a forecast discussion on Monday afternoon.

The replacement cycles occur when a secondary eye wall develops inside a storm, farther away from the center. That process can steal heat generation from the center, Franklin said. The winds begin to broaden and spread out to match the areas where heat is being released.

That's what happened in the hours before Hurricane Idalia made landfall in August 2023. Its "impacts were likely tempered somewhat by the fact that Idalia's inner core was quickly degrading as it underwent an eye wall replacement cycle immediately prior to landfall," the National Weather Service in Tallahassee wrote in an after-storm report.

After 36 hours, Milton is "expected to encounter a much less favorable environment with strong shear and dry air," Blake said. "Therefore, some weakening is anticipated before the hurricane reaches the Florida Gulf coast."

However, if replacement cycles occur that make Milton larger before it reaches the coast, the storm could be more resistant to wind shear, Klotzbach said.

Bigger, more powerful storms, like Hurricane Helene, are harder to disrupt.

“All things being equal you’d rather have a small intense storm than a large storm, for a number of reasons,” Franklin said. Smaller compact storms are more susceptible to weakening quickly and don’t drive the same kind of storm surge as a large one.

Milton is still likely to be "a large and powerful hurricane at landfall in Florida, with life-threatening hazards at the coastline and well inland."

Dinah Voyles Pulver covers climate change and the environment for USA TODAY. She's written about hurricanes, tornadoes and violent weather for more than 30 years. Reach her at [email protected] or @dinahvp.