July 22, 2024

Just a few weeks into hurricane season, the National Oceanic and Atmospheric Administration declared the end of El Niño, the warm streak of water in the Pacific Ocean that influences global weather. This makes an already dire outlook for cyclones even more dangerous – in April, scientists predicted five major hurricanes and 21 named storms in the North Atlantic alone – because El Niño tends to suppress the formation of such storms.

NOAA now predicts a 65 percent chance that La Niña, which is favorable for cyclones, will develop between July and September, when such events are most common. (La Niña is a band of cool water that forms in contrast to El Niño’s warm band.) At the same time, sea surface temperatures remain unusually high in the Atlantic Ocean — the kind of conditions that force monster storms.

The Atlantic is primed for a brutal hurricane season. But these cyclones aren’t just made of devastating winds and rain — they’re full of invaluable data that scientists will use to improve forecasting, giving everyone from local meteorologists to federal emergency planners better information to save lives.

Such insights will be especially critical if, for example, a hurricane rapidly intensifies — defined as an increase in sustained wind speeds of at least 35 mph in 24 hours — just before it reaches the coast and turns from a manageable crisis into a a deadly one. “Those cases right before landfall, where people are most vulnerable, are the nightmare scenario,” said Christopher Rozoff, an atmospheric scientist at the National Center for Atmospheric Research who models hurricanes. “That’s why it’s so important to improve it, and yet it’s been a major prediction challenge until somewhat recently.” (Which isn’t to say that weaker storms can’t also be catastrophic—for example, they can stall over a city and dump torrential rain.)

For such cataclysmic phenomena, hurricanes feed on a certain level of atmospheric dullness. El Niño suppresses the development of these storms by encouraging vertical wind shear, or winds moving at different speeds and directions at different altitudes. That mess tilts the vortex, which interferes with a hurricane’s ability to spin up uniformly. The La Niña that could form this summer, on the other hand, reduces that wind shear in the Atlantic, which provides ideal conditions for cyclones.

On the sea’s surface, extremely high temperatures has already turned the Atlantic Ocean into a huge pool of fuel for hurricanes to start forming. When this water evaporates, the vapor is entrained by the storm, forming drift clouds that release heat and lower the atmospheric pressure. It draws in air to create wind, which spins in a vortex.

If the ocean is warm enough and the vertical wind shear is low enough, a hurricane has the potential for rapid intensification. “The atmosphere usually drives the bus when it comes to rapid intensification — that’s certainly something that’s on my mind this hurricane season,” said Eric Blake, a senior hurricane specialist at the National Oceanic and Atmospheric Administration’s National Hurricane Center. “When you have extremely warm water, it just increases the chances of it occurring in areas where it might not normally occur.”

Last year, several hurricanes strengthened rapidly, including Hurricane Idalia, which tore into communities along the Florida coast. Across the Pacific, Hurricane Otis developed into a monster with astonishing speed before destroying Acapulco, Mexico. “That storm intensified from a tropical storm to a Category 5 in just over a 24-hour period,” Rozoff said. (For context, a Category 1 hurricane has sustained winds of at least 74 mph, while a Category 5 is at least 157 mph.) “We’ve seen improvements in forecasting and our ability to capture these events, but that particular forecast fails still, unfortunately by the numerical models, none of them foresaw this intensification to such an extreme storm that it would be so damaging.”

Because bubble strengthening involves highly complex interactions between the ocean and the air, it is notoriously difficult to predict. As the planet warms, warmer oceans provide more energy for hurricanes, and complex ripple effects across the atmosphere can also reduce wind shear along the Atlantic coast ahead. Indeed, a newspaper published last year found an explosion in the number of rapid intensification events near the coast in recent decades.

Not only are scientists trying to analyze why a particular hurricane would rapidly intensify in 2024, they have to figure out what to expect as the oceans get warmer and warmer, providing more and more cyclone fuel. It’s a moving target, one made of torrential rain and 160 mph winds. “We have a great database of weather that’s happening now, and we don’t necessarily have a great database of weather that will happen in the future,” said Sarah Gille, a physical oceanographer at the Scripps Institution of Oceanography. “So extreme storms are one window into that, which can help us get a better picture of what we can see.”

As hurricanes swirl across the Atlantic this summer, scientists will be ready. They can fly “Hurricane Hunter” plane in the cyclones, while loads of data such as wind speed, pressure and humidity are collected. (That’s another factor in major hurricanes: They love humidity but hate dry air.) They will then feed this data into models that try to predict rapid intensification. Scientists are increasingly using artificial intelligence to supercharge these algorithms, for example to train an AI to recognize patterns in satellite images of a hurricane, or precipitation in the core of the storm, to predict whether it will rapidly intensify or not.

Whether from an airplane or satellite, each new observation of these cyclones feeds into models that get better at understanding why hurricanes behave the way they do. That means better information for coastal cities to decide who to evacuate and when. “We got really good data at a time when the technology is improving, so I think that’s why we’ve made so much progress,” Rozoff said. “Every case of rapid intensification before landfall—whether well predicted or not—is a tragedy or at least a serious challenge to humanity. But it also provided us with good data.”

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