This past weekend, Hurricane Erin went through one of the most rapid intensifications of any Atlantic hurricane on record, something that may becoming more and more common.
Forecasters classify any storm that gains 35 mph of wind speed or more within 24 hours as rapidly intensifying. Erin leapt 85 mph in a day, from a tropical storm to a 160-mph Category 5 beast.
“It was pretty amazing,” said Brett Anderson, AccuWeather senior meteorologist, of the storm’s jump.
“Erin will go down in the history books as one of the fastest rapidly intensifying storms in history,” said hurricane expert Alex DaSilva, also of AccuWeather. “We expect to see more cases of extreme rapid intensification in the future as ocean temperatures continue to rise.”
A 2023 study showed that hurricanes are intensifying more rapidly now than in the past. Globally, the amount of rapidly intensifying hurricanes in coastal zones (within about 250 miles from shore) tripled from 1980 to 2020.
The study attributed the trend to a rise in sea-surface temperatures due to climate change. Those higher water temperatures fuel hurricanes. Sea-surface temperatures need to be around 80 degrees or higher to spark rapid intensification.
“Compared to 50 years ago, and especially in the last 20 years, we’ve seen a significant increase in ocean water temperatures, not just at the surface, but also at depth, which is what we call the ocean heat content,” said Anderson.
That hot water is the first element needed for rapid intensification. But a storm needs other factors to align. “The main factors are sea-surface temperature, wind shear, how a storm can vertically stack itself and organize, and also the moisture profile in the atmosphere,” said National Weather Service meteorologist George Rizzuto.
Dry air and wind shear cripple storms, but calm moist air and hot water fuel it.
Hurricane Erin prompts first watches on U.S. coast as odds increase for new system in Atlantic
The width of a storm also is a factor. Wide sprawling storms take longer to intensify; compact storms can spin up more quickly, almost like a spinning figure skater rotating faster as they pull their arms in.
A storm’s posture — upright or tilted — also affects rapid intensification. An upright storm is more likely to intensify.
According to the National Aeronautics and Space Administration, forecast models show that climate change “brings a slight increase in hurricane wind intensity. This change is likely related to warming ocean temperatures and more moisture in the air, both of which fuel hurricanes.”
Anderson agrees. “With climate change, we do expect an increase in the number of extreme hurricanes, but not necessarily more hurricanes total,” he said.
Some models actually show a decrease in storm frequency with climate change, but “a greater proportion of the storms that form will reach very intense (Category 4 or 5) levels.”
Early arrival
Erin also was early for a rapidly intensifying Category 5 storm, and tied Camille in 1969 for the fourth earliest-forming Category 5 ever recorded.
Sam Lillo, a meteorologist and software engineer for DTN Weather, reported over the weekend that the steep drop in Erin’s central pressure over 24 hours makes it the “fastest-deepening Atlantic hurricane” before September, beating Hurricane Emily’s 2005 record.
Research indicates that this early intensification is a new trend. According to a 2023 paper published in the science journal Nature, tropical cyclones are able to rapidly intensify about two weeks earlier in the season than they were in the past. That trend seems more likely in the Pacific Basin than in the Atlantic Basin.
Some of that increase may actually be due to a decrease in air pollution — with cleaner skies, more sunlight penetrates to the ocean, warming it.
According to Michael Lowry, hurricane specialist for WPLG-TV in Miami, only three previous Atlantic Basin storms have beaten Erin’s rate of acceleration: Wilma (2005), Felix (2007), and Milton (2024). Like Erin, Milton also jumped from a Category 1 to a Category 5 storm in about 24 hours. Milton made landfall shortly afterward, as a Category 3 near Siesta Key in October.
“These types of things are going to become more and more common in the coming decades,” said Anderson.
