Within just over 24 hours of forming in the Gulf of Mexico on Oct. 6, Hurricane Milton grew from a Category 1 hurricane to a Category 5, the most powerful class of storms. It was a jump in wind speeds of more than 153 kilometers per hour (95 miles per hour) in a day. This rapid intensification was likely fueled by climate change-linked warming of the Gulf waters, scientists say.
Milton’s explosive growth places it in a category of storms that didn’t exist before climate change put a thumb on the scale for hurricanes. “Extreme rapid intensification,” is the term meteorologists now use for storms that increase in wind speed by at least 56 km/h (35 mi/h) in a 24-hour period. Milton grew more than twice as quickly.
“This is a relatively newer term. We didn’t have a term for this before because we didn’t see storms extremely rapidly intensify just a couple decades ago,” Shel Winkley, a meteorologist and weather and climate engagement specialist with Climate Central, told Mongabay by phone.
Milton is the 40th Atlantic hurricane to meet the new designation since 1980.
The other unusual thing about Milton is where it formed. Typically, big hurricanes, like Katrina in 2005, form off the coast of Africa and gain energy as they move west across the Atlantic. But Milton was formed entirely within the Gulf, just two weeks after Hurricane Helene passed through the same body of water.
All hurricanes form over the ocean and are fueled by warm seawater. Hurricanes Helene and Milton both gained their energy from the abnormally high sea surface temperatures in the Gulf of Mexico, which is 1.4º Celsius (2.5º Fahrenheit) above average for this time of year.
Scientists with Climate Central used climate modeling to determine that “those temperatures were made up to 400-800 times more likely by climate change.”
Likewise, the warm Gulf water also helped create the right conditions for the dozens of powerful tornadoes associated with Milton. Tornadoes are commonly associated with hurricanes; a combination of unstable air and spinning, or wind shear, can give rise to them. Hurricane tornadoes tend to be weak and short-lived, but the Milton tornadoes were large and remained on the ground long enough to kill at least six people.
“These warmer-than-average waters allow for a more unstable air mass and moisture to interact with the dynamics of the hurricane to create a more susceptible environment for tornadoes,” Winkley said.
The Gulf’s warmer-than-normal waters extend beyond just surface temperatures. Deeper water temperatures are also significantly elevated. So even after the upwelling that followed Helene, there was plenty of hot Gulf water to fuel Milton.
“The takeaway when you look at the climate change aspect of this is that there isn’t that mechanism to try to cool down the waters and keep these storms in check anymore,” Winkley said.
Banner image: Hurricane Milton as seen from space. Image courtesy of NOAA
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