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- El Niño is expected to reduce Atlantic hurricane activity this season, NOAA predicted on Thursday.
- Conversely, the developing El Niño may increase Pacific storm activity.
- The eastern Pacific hurricane season started May 15; the Atlantic season begins on June 1.
MIAMI — A developing El Niño that is forecast to get quite strong will likely dampen the upcoming Atlantic hurricane season, but it won't make the potentially deadly storms disappear, federal and outside meteorologists predict.
The National Oceanic and Atmospheric Administration on Thursday issued its seasonal outlook for the Atlantic, giving a 55% chance of a below-average season. The agency forecasts eight to 14 named storms, with three to six of them becoming strong enough to hit hurricane status and one to three of those intensifying to major hurricanes.
A normal hurricane season has 14 named storms, seven of them becoming hurricanes and three of them reaching major hurricane level, which is more than 110 mph.
Eighteen other groups, private and academic, have also forecast what they think the season will be like, and most call for a below-average summer and fall. Those other forecasts average a dozen named storms, only five becoming hurricanes and two of those being major ones. Those forecasts also call for the Accumulated Cyclone Energy index, which takes into account the strength and duration of storms, to be 80% of normal.
Colorado State University, which pioneered the science of hurricane seasonal forecasting in 1984, is predicting the lowest overall activity since 2015, which was the strongest El Niño in the last 75 years. And that forecast is likely to be revised to even lower numbers in June, said Colorado State's hurricane expert Phil Klotzbach.
This is after nine of the last 10 Atlantic hurricane seasons have been above normal or even hyperactive, Klotzbach said. Last year started slow, but then had a burst, producing a near-record total of three Category 5 hurricanes, including Melissa, which devastated Jamaica and Cuba, said Suzana Camargo, a climate scientist and tropical weather expert at Columbia University.
Inflation-adjusted damage across the globe from tropical cyclones has increased from an average of $11.4 billion a year in the 1980s to $109.7 billion a year over the past 10 years, with three-quarters of the damage done in the Atlantic, Gulf of Mexico and Caribbean, according to insurance giant Munich Re.
Hurricanes, typhoons and cyclones are the same weather event, with the different names being used in different parts of the world.
"We should expect a less active year than certainly what we've seen recently, and perhaps significantly so below average," said University at Albany atmospheric scientist Kristen Corbosiero. "But again, it only takes one to cause real devastation and destruction in the mainland U.S. or even in Hawaii."
El Niño decapitates Atlantic storms
It's mostly because of "the elephant in the room," which is an El Niño, Camargo said.
An El Niño is the natural and cyclic warming of parts of the central Pacific that warps weather patterns around the globe, especially during winter. Scientists for decades have found a correlation between an El Niño and below-average Atlantic hurricane activity and stronger and more storms in the central and eastern Pacific. This year, many forecasts are calling for a strong, super-strong, or even record-setting intense El Niño. During a La Niña, the cool flip side of El Niño, the Atlantic is generally busier with stronger storms.
There's a 98% chance that there will be an El Niño this summer and an 80% chance it will be moderate or strong, NOAA Administrator Neil Jacobs said Thursday.
Atlantic hurricane seasons when an El Niño reaches strong or very strong status have two-thirds as many named storms and half as many hurricanes as the 1991-2020 average, according to an Associated Press analysis of storm and El Niño statistics.
El Niños fight Atlantic storm formation in several ways, especially with cross winds about 1 mile to 7 miles above the surface, "which can basically blow apart the thunderstorms that make up" a hurricane, Corbosiero said.
"A stronger than normal wind shear tends to tilt storms as they try to develop," said University at Albany atmospheric scientist Brian Tang. "It pushes dry air into storms. And prevents storms from developing in the first place. And if they do develop, it also prevents them from intensifying."
El Niño reduces the number and intensity of weaker storms, but once a storm hits hurricane status with 74 mph winds, "they can be kind of like a self-feeding entity" and are less prone to being dampened by El Niño's wind shear, said Matthew Rosencrans, lead hurricane season forecaster with NOAA's National Weather Service.
Forecasts for peak hurricane season show strong wind shear from the west in the main development region for the largest and long-lasting hurricanes that come off of Africa and develop as they head west over the Atlantic, Klotzbach said. Fewer of these types of storms happen during El Niños.
In the 15 strongest El Niño years since 1950, 37 named storms, 11 hurricanes, and three major hurricanes made landfall on the continental United States, but in the 15 coldest La Niña years, 61 named storms, 31 hurricanes, and 10 major hurricanes hit America's Gulf and Atlantic coasts, according to Klotzbach. He said El Niño reduces the number of hits along the Atlantic coast, but has less influence on the number of Gulf coast landfalls.
In addition to El Niño, dry conditions in Africa and water in the Atlantic being only slightly warmer than normal contribute to the forecast of a weaker season, Rosencrans said.
Opposite effect in the Pacific
El Niños and La Niñas have the opposite effect on storms in the central and eastern Pacific as they do in the Atlantic, so experts are expecting a busier season in those regions. Jacobs said there's a 70% chance that the eastern Pacific will have an above-normal season.
NOAA forecasts 15 to 22 named storms in the Pacific, with nine to 14 becoming hurricanes and five to nine of those being major hurricanes. (The average is 15 named storms, eight hurricanes and four major hurricanes.) Rosencrans said the main area of central Pacific storm development shifts closer to Hawaii during El Niños.
Eastern Pacific storms near Baja Mexico tend to "go west, affect the fishies and little else," Corbosiero said. But at times they can turn east or north and cause massive damage, as in Hurricane Otis in 2023 that smashed into Mexico, or 1992's Hurricane Lester, which caused heavy rains in the Southwest, she said.
Hawaii is a small island chain in a big ocean that can be threatened. In 1992, an El Niño year when there were few Atlantic storms (though Miami was devastated by Hurricane Andrew), Hawaii was hit by Hurricane Iniki.
Further west toward Asia and India, "your odds of any storm forming becoming a super typhoon go up significantly in El Niño," Klotzbach said.
The eastern Pacific hurricane season started May 15, and the Atlantic season begins June 1, and both end Nov. 30.
