Though July was quiet, experts at Colorado State say the remainder of the 2024 Atlantic hurricane season should be “extremely active,” with the likelihood of 10 hurricanes yet to form.
The department of atmospheric science there has released its final 2024 hurricane season forecast for the year, calling for a “well-above-average” August through November.
One bright note is that it actually reduced its number of named storms from its July forecast, from 25 down to 23. The 1991 to 2020 average is 14.4.
The Colorado State team still expects 12 hurricanes (the 1991-2020 average was 7.2), and is forecasting that six of those will reach major hurricane strength (Category 3, 4 or 5). The 1991-2020 average is 3.2.
This season’s previous storms, Hurricanes Beryl and Debby, as well as Tropical Storms Alberto and Chris, are included in the numbers. That means the team is calling for 10 more hurricanes between August and Nov. 30, when hurricane season ends.
Forecasters predicted that 2024 will have about 190% of the average hurricane activity from 1991–2020. Last year had about 120%.
The most impactful Atlantic basin hurricane of 2023 was Idalia, which made landfall as a Category 3 storm on Aug. 30, in the Big Bend region of Florida, causing eight fatalities.
The Colorado State team said it has higher-than-normal confidence that this season will be extremely busy. Several factors play a role.
2024 has been marked by unusually warm sea-surface temperatures in the tropical Atlantic. All that warm water can fuel storm formation. Additionally, the warm water tends to create lower atmospheric pressure and an unstable atmosphere, which also is favorable for storms.
Wind shear, which can topple hurricanes, has been below normal in June and July, which usually indicates low shear in the peak of the season from August to October.
The El Niño, which can ramp up wind shear in the Atlantic Basin, has faded, and a potential La Niña could kick in in the coming month. That would likely weaken wind shear even more, and favor storm intensification.
Learning from history
So far, 2024’s ocean and atmosphere conditions look a lot like those of past active seasons, such as 1933, 1995, 2005, 2010 and 2020, said Phil Klotzbach, senior research scientist in the department of atmospheric science at CSU and lead author of the report.
The report also predicted that for the remainder of the season, the east coast of the U.S., including the Florida peninsula, has a 30% chance of a major hurricane making landfall. The full season average from 1880–2020 is 21%.
The Gulf Coast from the Florida panhandle westward to Brownsville has a 38% chance of a major hurricane making landfall. The full season average for that region from 1880–2020 is 27%.
