Colorado State University has updated its hurricane season forecast, calling for a more active season than the already “extremely active” forecast from June.
The forecast team there used data collected through the season thus far to adjust its predictions. In nearly every category, forecasters are calling for the seasons to be more robust:
— The number of named storms jumped from 23 to 25. The 1991 to 2020 average is 14.4.
— Total hurricanes jumped from 11 to 12. The 1991 to 2020 average is 7.2.
— Major hurricanes increased from five to six. The 1991 to 2020 average is 3.2.
— Accumulated Cyclone Energy (ACE) increased from 210 to 230. The 1991 to 2020 average is 123.
Accumulated Cyclone Energy is sum of tropical storm and hurricane wind duration and intensity, so experts consider it a more accurate depiction of a season’s activity than simply the number of storms.
Climate researcher Brian McNoldy with the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science wrote on X that Hurricane Beryl, the earliest Category 5 hurricane on record, contributed mightily to this year’s ACE.
Beryl “has boosted the 2024 tally to an incredible level for so early in the season. The ACE is higher than any other year on record by this date, and is actually already higher than 14% of all entire hurricane seasons going back to 1851!”
The Colorado State report also details the probabilities of at least one major hurricane landfall in different regions after July 8.
Forecasters said the continental U.S. coastline has a 57% chance of a major hurricane strike. Historically, there’s a 43% chance.
And the U.S. east coast, including Florida, has a 31% chance of a major hurricane strike. Historically for the east coast, there’s a 21% chance.
The Gulf Coast from the Florida Panhandle to the Mexico border has a 38% chance this year. Historically, there’s a 27% chance.
Colorado State’s Philip Klotzbach, who specializes in Atlantic basin hurricane forecasts, wrote on X that one reason for the very active forecast was the “significant potential for La Niña development. La Niña typically increases Atlantic hurricane activity via decreases in Caribbean/tropical Atlantic vertical wind shear,” he wrote.
A La Niña is a natural weather phenomenon in which cool water upwellings along the Pacific coast of South America result in global weather patterns, including less wind over the tropical Atlantic.
Another factor is high sea-surface temperatures. Hot water fuels hurricanes, and the Atlantic has been exceptionally hot this year.
As of July 7, average sea surface temperatures in the tropical Atlantic were actually just below what they were during 2023, which was exceptionally hot. But they’re well above the 1991 to 2020 average. Hurricane Beryl may have helped cool this off a tad, and a massive plume of Saharan dust that is currently over the Atlantic can also cool oceans to some extent, according to McNoldy.
Klotzbach went on to write that while there as been a bit of anomalous cooling in parts of the Atlantic, “most of the North Atlantic remains much warmer than normal, favoring hurricane activity. This anomalous warmth is [the] primary reason why CSU’s seasonal hurricane forecast for 2024 is calling for such an active season.”
