A developing El Nino that is forecast to become quite strong will likely dampen the upcoming Atlantic hurricane season, but it won't make the potentially deadly storms disappear, according to federal and outside meteorologists.
NOAA Seasonal Outlook
The National Oceanic and Atmospheric Administration (NOAA) issued its seasonal outlook for the Atlantic on Thursday, 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 reach hurricane status and one to three of those intensifying to major hurricanes. A normal hurricane season has 14 named storms, seven hurricanes, and three major hurricanes (winds over 110 mph or 177 kph).
Other Forecasts Agree
Eighteen other groups, both private and academic, have also issued forecasts, most calling for a below-average summer and fall. Their average prediction is a dozen named storms, only five becoming hurricanes, and two reaching major hurricane status. The Accumulated Cyclone Energy index, which accounts for storm strength and duration, is expected to be 80% of normal.
Colorado State University, which pioneered hurricane seasonal forecasting in 1984, predicts the lowest overall activity since 2015, the strongest El Nino in 75 years. Hurricane expert Phil Klotzbach said this forecast is likely to be revised even lower in June.
Recent Active Seasons
This outlook follows nine of the last 10 Atlantic hurricane seasons being above normal or hyperactive, Klotzbach noted. Last year started slow but produced a near-record three Category 5 hurricanes, including Melissa which devastated Jamaica and Cuba, said Suzana Camargo, a climate scientist at Columbia University.
Inflation-adjusted global damage from tropical cyclones has risen from an average of $11.4 billion per year in the 1980s to $109.7 billion per year over the past decade, with three-quarters occurring in the Atlantic, Gulf of Mexico, and Caribbean, according to Munich Re.
Hurricanes, typhoons, and cyclones are the same weather event, with different names used in different regions.
"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 Nino's Impact on Storms
El Nino is the primary factor, described as "the elephant in the room" by Camargo. El Nino is the natural, cyclic warming of parts of the central Pacific that alters weather patterns globally, especially in winter. Scientists have long observed a correlation between El Nino and below-average Atlantic hurricane activity, with stronger storms in the central and eastern Pacific. This year, many forecasts call for a strong, superstrong, or even record-setting El Nino. During La Nina, the cool opposite, the Atlantic is generally busier with stronger storms.
NOAA Administrator Neil Jacobs said Thursday there is a 98% chance of an El Nino this summer and an 80% chance it will be moderate or strong. An Associated Press analysis of storm and El Nino statistics shows that Atlantic hurricane seasons with strong or very strong El Ninos have two-thirds the named storms and half the hurricanes of the 1991-2020 average.
El Ninos inhibit Atlantic storm formation in several ways, particularly through cross winds 1 to 7 miles (1.5 to 11 kilometers) 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," added 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 Nino reduces the number and intensity of weaker storms, but once a storm reaches hurricane status with 74 mph winds, "they can be kind of like a self-feeding entity" and are less prone to being dampened by wind shear, said Matthew Rosencrans, lead hurricane season forecaster at NOAA's National Weather Service.
Forecasts for peak hurricane season show strong wind shear from the west in the main development region for large, long-lasting hurricanes that originate off Africa and develop as they head west over the Atlantic, Klotzbach said. Fewer such storms occur during El Ninos.
In the 15 strongest El Nino years since 1950, 37 named storms, 11 hurricanes, and three major hurricanes made landfall on the U.S. mainland, while in the 15 coldest La Nina years, 61 named storms, 31 hurricanes, and 10 major hurricanes hit the Gulf and Atlantic coasts, according to Klotzbach. He noted that El Nino reduces Atlantic coast landfalls but has less influence on Gulf coast hits.
In addition to El Nino, dry conditions in Africa and only slightly warmer than normal Atlantic waters contribute to the weaker season forecast, Rosencrans said.
Pacific Activity to Increase
El Nino and La Nina have opposite effects on storms in the central and eastern Pacific compared to the Atlantic, so experts expect a busier season there. Jacobs said there is a 70% chance of an above-normal eastern Pacific season. NOAA forecasts 15 to 22 named storms, with nine to 14 becoming hurricanes and five to nine major hurricanes. The average is 15 named storms, eight hurricanes, and four major hurricanes. Rosencrans said the main central Pacific storm development area shifts closer to Hawaii during El Ninos.
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 with Hurricane Otis in 2023 that smashed into Mexico, or 1992's Hurricane Lester, which caused heavy rains in the U.S. Southwest.
Hawaii, a small island chain in a large ocean, can be threatened. In 1992, an El Nino year with 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 Nino," Klotzbach said.
The eastern Pacific hurricane season started May 15, and the Atlantic season begins June 1; both end November 30. El Ninos can also lengthen the season, said John Bravender, a weather service meteorologist in Honolulu. "With the warmer waters across the area, not only can hurricanes maintain their strength at higher latitudes, but also longer through the year."
Hawaii is preparing for hurricanes as parts of the state still recover from recent back-to-back storms that caused catastrophic flooding, said Governor Josh Green.
