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Meteorologists expect this year’s Atlantic hurricane season to be less active than normal, pointing to a developing El Niño that can disrupt the atmospheric conditions hurricanes need to grow. The outlook from the National Oceanic and Atmospheric Administration said that while fewer storms may form, storms that do develop can still bring damaging impacts to areas including the mainland U.S. and Hawaii.
NOAA issued its seasonal outlook for the Atlantic, giving a 55% chance of a below-average season. In that forecast, the agency predicted eight to 14 named storms, with three to six becoming hurricanes and one to three of those intensifying into major hurricanes.
The seasonal outlook builds on a broader expectation that many people associate with El Niño: it tends to correlate with fewer storms and weaker overall hurricane activity in the Atlantic. Seth Borenstein, reporting for the Associated Press, said that multiple forecasts—including NOAA’s and those from other groups—call for a below-average summer and fall, though none promise the storms will disappear.
In explaining why El Niño may damp Atlantic storm formation, scientists pointed to changes in the wind patterns aloft that can interfere with the thunderstorms that organize into hurricanes. Kristen Corbosiero of the University at Albany said El Niño is “the elephant in the room,” and described how conditions aloft can “basically blow apart the thunderstorms that make up” a hurricane. Corbosiero also said a stronger-than-normal wind shear can tilt developing storms, push dry air into them, and prevent intensification.
NOAA’s forecasting also incorporates how hurricanes behave once they reach peak strength. Matthew Rosencrans, lead hurricane season forecaster with NOAA’s National Weather Service, said that El Niño’s wind shear influences weaker systems, but once a storm reaches hurricane status—with winds of 74 mph—storms can become “self-feeding” and less prone to being dampened. Rosencrans added that other factors outside El Niño also affect the Atlantic outlook, including dry conditions in Africa and ocean temperatures in the Atlantic that are only slightly warmer than normal.
Other researchers said the Atlantic forecast arrives after a pattern of recent active seasons. Phil Klotzbach of Colorado State University said the university is predicting “the lowest overall activity since 2015,” which he described as the strongest El Niño in the last 75 years, and he said the forecast is likely to be revised to even lower numbers in June. Klotzbach also noted that nine of the last 10 Atlantic hurricane seasons had been above normal or even hyperactive.
Even with a weaker Atlantic outlook, forecasters emphasized that a low overall count does not eliminate the risk of catastrophe. Corbosiero said, “We should expect a less active year than certainly what we’ve seen recently, and perhaps significantly so below average,” but added that “it only takes one to cause real devastation and destruction in the mainland U.S. or even in Hawaii.” She and other scientists said the forecast cannot be treated as a guarantee that storms won’t reach damaging strength.
Experts also said El Niño shifts hurricane risk patterns across the Pacific basin in the opposite direction from the Atlantic. The Associated Press report said NOAA expects a 70% chance that the eastern Pacific will have an above-normal season, with forecasts of 15 to 22 named storms there and nine to 14 becoming hurricanes, including five to nine major hurricanes. Rosencrans said storm development in the central Pacific can shift closer to Hawaii during El Niño periods, and John Bravender, a weather service meteorologist in Honolulu, said El Niño can also make hurricane season longer because warmer waters can support storms at higher latitudes and for more months.
Hawaii’s government indicated it is preparing for a season with the possibility of impacts even if the Atlantic is quieter. Gov. Josh Green said the state is preparing for hurricanes as parts of Hawaii continue to recover from recent back-to-back storms that caused catastrophic flooding.
Elsewhere, outside meteorologists reinforced the Atlantic-to-Pacific tradeoff by comparing what happens when El Niño strengthens versus when La Niña takes over. Klotzbach said that 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, compared with 61 named storms, 31 hurricanes and 10 major hurricanes in the 15 coldest La Niña years that hit America’s Gulf and Atlantic coasts. He said El Niño reduces Atlantic coast hits but has less influence on Gulf coast landfalls.
The Atlantic hurricane season is set to begin June 1 and run through November 30, while the eastern Pacific season begins May 15 and also ends November 30. The Associated Press report said hurricanes, typhoons and cyclones refer to the same kind of weather system, with different names used in different ocean regions.
Associated Press writer Jennifer Sinco Kelleher contributed to this report from Honolulu.