A key factor in the rapid intensification of Hurricane Ian is warm ocean water.
On Monday morning, Hurricane Ian had wind speeds of 75 miles per hour. Just 48 hours later, those speeds had more than doubled. On Wednesday, as the storm made landfall in southwestern Florida, Ian’s wind hit 155 mph — just shy of a Category 5 storm, the most severe category for a hurricane.
Such rapid growth is known by meteorologists as “rapid intensification.” It’s defined as storms whose wind speeds increase by roughly 35 mph or more in less than 24 hours. “Ian definitely met that criteria,” said Paul Miller, a professor of oceanography and coastal sciences at Louisiana State University.
While wind speed isn’t the only force that makes storms dangerous, hurricanes that rapidly intensify are especially worrisome. They can easily catch coastal communities off guard, giving them little time to prepare, Miller said.
So how did Ian get so big, so fast?
It’s an important question, as storms like this one are highly destructive and are likely to become more frequent in the years to come. What made Hurricane Ian strengthen so quickly
There are three main ingredients that, when mixed together, can result in a rapidly intensifying hurricane: moist air, low wind shear (wind coming from different directions or at different speeds), and warm ocean water.
“All three of those things create a favorable ecosystem for a hurricane to establish circulation and intensify,” Miller said.
Ian had them all. As it developed several days ago, the storm system faced some disrupting winds, but there was little shear as it grew over the last few days, Miller said. And Ian has largely avoided a region of dry air in the Gulf of Mexico. (Had Ian hit Florida farther north, it might have deteriorated faster, he said.)
Then there’s the warm ocean water. The Gulf of Mexico has been unseasonably warm this summer, according to the National Weather Service. And climate change is heating the Caribbean ocean by a little over 1 degree C (1.8 degrees Fahrenheit) per century.
“Even small changes — half a degree C, or a degree — can really make a big difference,” said Brian McNoldy, a hurricane researcher at the University of Miami.
