How Hurricane Milton exploded into a terrifying Category 5 storm in just hours

Between Sunday and Monday morning — a mere 24 hours — Hurricane Milton grew from a tropical storm to a fierce Category 5 hurricane. With wind speeds pushing 180 miles per hour Monday afternoon, before weakening slightly Tuesday, Milton is one of the strongest hurricanes ever recorded in the Atlantic. Forecasters expect Milton, which is once again a Category 5 storm as it churns in the Gulf of Mexico, to make landfall in western Florida on Wednesday night. The storm may lose steam before then as it faces disruptive winds and dry air, yet Milton is still expected to be an “extremely dangerous” hurricane upon arrival, according to the National Hurricane Center. Storm surge in the densely populated Tampa Bay, which could see a direct hit, could reach 15 feet, the Center said in an advisory Monday. Milton is not the typical Atlantic hurricane, according to Jonathan Lin, an atmospheric scientist at Cornell University. “It is exceedingly rare for a hurricane to form in the western Gulf, track eastward, and make landfall on the Western coast of Florida,” he said in an email Monday. “There are not really any hurricanes on record that have done this and made landfall at a Category 3+ status.” What’s even more unusual is how quickly the storm intensified, defying forecasts and gaining more than 100 miles per hour in wind speed between Sunday morning and early Monday afternoon. Milton had “some of the most explosive intensification this forecaster has ever witnessed!” a National Weather Service forecaster wrote on X Monday. Why Milton intensified so quickly The simplest explanation is unusually warm ocean water. Take a look at the chart below. It’s showing ocean heat in the Gulf of Mexico, which is near a record high. The red line is 2024 and the blue line is the average over the last decade. And heat is a key ingredient in rapid intensification, according to Brian McNoldy, a climatologist at the University of Miami, who made the chart below. Put simply, hotter water evaporates more readily, and rising columns of warm, moist air from that evaporation fuel rapid intensification. [Image: A chart of ocean heat content in the Gulf of Mexico https://platform.vox.com/wp-content/uploads/sites/2/2024/10/ohc_gulf-3.png?quality=90&strip=all] It’s not entirely clear what has caused the Gulf to warm, though scientists suspect a combination of factors, including climate change — which raises the baseline ocean temperature — as well as lingering effects of El Niño, natural climate variability, and perhaps even a volcanic eruption. Another key to Milton’s explosive growth is a lack of wind shear in its path, according to Benjamin Kirtman, director of the Cooperative Institute for Marine & Atmospheric Studies, a joint initiative of the University of Miami and the National Oceanic and Atmospheric Administration (NOAA). Wind shear describes the change of wind speed and direction — basically, chaotic air — and it can disrupt hurricanes. The storm is expected to encounter more shear as it approaches Florida, which will blunt its strength and make it likely to weaken before landfall. What’s more, McNoldy said, is that Milton is also relatively small in width. As of Monday, Hurricane-force winds extended only about 30 miles from the storm center. Small hurricanes are “generally more prone to ups and downs,” he told Vox, because they’re influenced more easily by weather phenomena. Although Milton is set to grow in size before it reaches Florida (in part, through a complex process of eyewall replacement), it likely won’t be huge when it makes landfall — again, speaking in terms of diameter. “That is all-around good news,” he said. Smaller storms tend to produce less surge, which describes a rise in sea level. Compared to Hurricane Helene, which was an enormous system, for example, forecasters expect Milton to produce less storm surge. That doesn’t mean experts like McNoldy, a Florida resident, aren’t worried. As of Monday, Milton appears to be headed straight for the Tampa Bay area, the most densely populated region of the state’s west coast. This is the same region where a dozen people were killed by Hurricane Helene in recent days. “This is a very ominous forecast,” McNoldy said. “It will still be an extremely strong hurricane.” Update, October 8, 5:50 pm ET: This story was originally published on October 7 and has been updated with new information about Hurricane Milton’s forecast.