CSU forecasters call for above-average hurricane season in Atlantic a year after worst ever

• Forecasters at Colorado State University are predicting an above-average hurricane season in the Atlantic Ocean this year.
• The April forecast is the first of four prepared by the CSU team each year. Updated forecasts are scheduled to be released June 11, July 9 and Aug. 6.
• CSU’s early April forecast a year ago was right on when it came to the number of total hurricanes (11) and major hurricanes (five) in the Atlantic Basin.

Forecasters at Colorado State University are predicting an above-average hurricane season in the Atlantic Ocean this year, citing warmer than average sea-surface temperatures and dynamic and thermodynamic conditions that are conducive to hurricane development.

The early April forecast, released Thursday at the National Tropical Weather Conference in San Antonio, Texas, by the CSU tropical weather and climate research team, calls for nine hurricanes in the Atlantic Basin, including four major hurricanes of Category 3 or higher.

There were five major hurricanes, as the CSU team correctly predicted in early April 2024, in the Atlantic Basin last year, including two that reached Category 5 status — Beryl in late June and Milton in October.

“We’ve had quite a few years where there were more hurricanes in general, but when you look at major hurricanes making landfall, that was one of the worst,” co-author Levi Silvers told the Coloradoan on Thursday. “As far as this year goes, we’re calling for a hurricane season that’s above average as far as statistics go, but not as bad as last year.”

Hurricane season in the Atlantic Basin runs from June 1 through Nov. 30, the report notes.

The April forecast is the first of four each year prepared by the CSU team, led by Phil Klotzbach in the Department of Atmospheric Science. Silvers, a research scientist, and Professor Michael Bell, are co-authors.

Updated forecasts are scheduled to be released June 11, July 9 and Aug. 6.

“The skill of CSU’s forecast updates increases as the peak of the Atlantic hurricane season approaches,” the report reads.

CSU’s early April forecast a year ago was right on when it came to the number of total hurricanes (11) and major hurricanes (five) in the Atlantic Basin. Silvers’ early October suggestion following the devastation of Helene, a Category 4 hurricane, that conditions were ripe for more major storms before the season was over was also realized. Milton made landfall on Florida’s southwest coast less than two weeks later.

“Under most ways of looking at last season, it was a really intense season that had really dramatic impacts, both to the United States and the Caribbean communities,” Silvers said. “We don’t expect this year to be as bad.”

The CSU forecasts, which the late William Gray began in 1984, are based on a “statistical prediction scheme” utilizing roughly 40 years of past data, the report said. Also included are dynamic statistical models based on 25 to 40 years of data from the European Centre for Medium Range Weather Forecasts, United Kingdom Meteorological Office, Japan Meteorological Agency and Euro-Mediterranean Center on Climate Change. Each of those models calls for nine or more hurricanes in the Atlantic this year, the report notes.

“All of our model guidance is pointing towards an above-normal season,” the report reads.

Sea-surface temperatures are warmer than average, but not as warm as they were last year. And vertical wind shear that helps prevent the formation and strengthening of hurricanes is stronger, Silvers said.

Those conditions, he said, are subject to change. But data suggests the trends they predicted in their models will likely persist.

The accuracy of last year’s forecasts, Silvers said, “gives us more confidence in the models that we’re using, and that’s a big difference from 20 to 30 years ago. These models are not perfect, but they’re far better than they used to be.”

The biggest improvement, Silvers said, has been in increased monitoring of water temperatures in the Pacific that make it easier to predict the impact of La Nina or El Nino conditions that disrupt standard global weather patterns.

La Nina conditions that existed during the 2024 hurricane season typically bring stronger-than-average trade winds that push warmer water in the Pacific toward Asia, cooling waters along the West Coast of the United States and pushing the jet stream south. That leads to warmer-than-average winter air and sea-surface temperatures along the U.S. Gulf and East coasts, according to the National Oceanic and Atmospheric Administration. El Nino has the reverse effect, often bringing increased rain and flooding to the U.S. Gulf and East Coasts while also making it more difficult for hurricanes to form and strengthen.

CSU’s early April forecast for the Atlantic Basin this year calls for 17 named storms, including nine that will become hurricanes and four that will be Category 3, 4 or 5 hurricanes, with wind speeds exceeding 110 mph that can cause structural damage to buildings, uproot trees and widespread power outages.

The forecast also provides statistical probabilities for where major hurricanes might strike that are all higher than the annual average from 1880-2020. The probability of a major hurricane striking somewhere on the coastline of the continental U.S. is at 51% compared to the annual average of 43%. The probability of a major hurricane striking on the East Coast of the U.S., including the entire Florida peninsula, is 26% compared to an annual average of 21%. And the probability of a major hurricane striking the U.S. Gulf Coast, from Cedar Key on the Florida panhandle to Brownsville, Texas, is at 33% compared to the average from 1880-2020 of 27%.

“Everyone should realize that it is impossible to precisely predict this season’s hurricane activity in early April,” the report reads. “There is, however, much curiosity as to how global ocean and atmosphere features are presently arranged with respect to the probability of an active or inactive hurricane season for the coming year.”

Reporter Kelly Lyell covers education, breaking news, some sports and other topics of interest for the Coloradoan. Contact him at kellylyell@coloradoan.com,x.com/KellyLyell and  facebook.com/KellyLyell.news.