Hurricane Milton is turning into a strong Category 5 storm on its way to Florida – this is how rapid intensification works

Hurricane Milton went from barely hurricane strength to a dangerous Category 5 storm in less than 24 hours as it moved across the Gulf of Mexico toward Florida.

As wind speeds increased, Milton became one of the fastest intensifying storms ever. And with sustained winds of 180 miles per hour on October 7, 2024 and very low pressure, it also became one of the strongest storms of the year.

Less than two weeks after the devastating impact of Hurricane Helene, such a storm was the last thing Florida wanted to see. Hurricane Milton was expected to make landfall as a major hurricane late on October 9 or early October 10 and had already triggered extensive evacuations.

So what exactly is rapid intensification and what does global climate change have to do with it? We research hurricane behavior and teach meteorology. Here's what you need to know:

What is rapid intensification?

Rapid intensification is defined by the National Weather Service as an increase in a tropical cyclone's maximum sustained wind speed of at least 30 knots – about 35 miles per hour – in a 24-hour period. This increase may be enough to escalate a storm from Category 1 to Category 3 on the Saffir-Simpson scale.

Wind speeds in Milton increased from 80 mph to 175 mph from 1 p.m. Sunday to 1 p.m. Monday, and pressure dropped from 988 millibars to 911.

The National Hurricane Center had warned that Milton was likely to develop into a major hurricane, but such rapid intensification can surprise people, especially if it occurs close to landfall.

Hurricane Michael caused billions of dollars in damage in 2018 when it quickly intensified into a Category 5 storm just before making landfall near Tyndall Air Force Base in the Florida Panhandle. In 2023, Hurricane Otis' maximum wind speed increased by 100 miles per hour in less than 24 hours before hitting Acapulco, Mexico. Hurricane Ian also rapidly strengthened in 2022 before making landfall just south of where Milton is expected to cross Florida.

What causes hurricanes to intensify quickly?

Rapid intensification is difficult to predict, but there are some driving forces.

• Ocean Heat: Warm sea surface temperatures, particularly as they penetrate into deeper layers of warm water, provide the energy needed for hurricanes to intensify. The deeper the warm water, the more energy a storm can harness and the stronger it is.

• Low wind shear: Strong vertical wind shear—a rapid change in wind speed or direction with altitude—can disrupt a storm's organization, while low wind shear causes hurricanes to grow more quickly. In the case of Milton, atmospheric conditions were particularly conducive to rapid intensification.

• Moisture: Higher sea surface temperatures and lower salinity increase the amount of moisture available to storms, leading to rapid intensification. Warmer water provides the heat needed for moisture to evaporate, while lower salinity helps retain that heat near the surface. This allows more sustained heat and moisture to be transferred to the storm, resulting in faster and stronger intensification.

• Thunderstorm activity: Internal dynamics, such as B. Outbreaks of intense thunderstorms within a cyclone's rotation can reorganize a cyclone's circulation and result in a rapid increase in strength even when other conditions are less than ideal.

Research has shown that, worldwide, most Category 3 and above hurricanes tend to intensify rapidly over their lifetime.

How does global warming affect the strength of hurricanes?

If it seems like you've been hearing about rapid intensification a lot more in recent years, that's partly because it's more common.

A 2023 study examining links between rapid intensification and climate change found that the past four decades have seen an increase in the number of tropical cyclones experiencing rapid intensification. This includes a significant increase in the number of hurricanes, which rapidly intensify several times as they develop. Another analysis that compared trends from 1982 to 2017 with climate model simulations found that natural variability alone could not explain this increase in rapidly intensifying storms, indicating a likely role of human-caused climate change.

How future climate change will affect hurricanes is an active area of ​​research. However, as global temperatures and oceans continue to warm, the frequency of major hurricanes is expected to increase. The extreme hurricanes of recent years, including Beryl in June 2024 and Helene, are already raising concerns about the increasing impact of warming on the behavior of tropical cyclones.

This article was republished from The Conversation, a nonprofit, independent news organization that brings you facts and trusted analysis to help you understand our complex world. It was written by: Zachary Handlos, Georgia Institute of Technology and Ali Sarhadi, Georgia Institute of Technology

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Zachary Handlos receives funding from the National Science Foundation. He is affiliated with the American Meteorological Society as the new Chairman of the Board on Higher Education. He is also an academic faculty partner for the Georgia Climate Project.

Ali Sarhadi receives funding from NSF and Georgia Tech.