Colorado State University’s annual April hurricane forecast is calling for an “extremely active” Atlantic hurricane season for 2024. A team of researchers estimates there will be 11 hurricanes in the Atlantic Basin — the most they’ve ever predicted in their April outlook.
Their report estimates the number of named storms, hurricanes and major hurricanes and offers percentage chances of landfall in vulnerable regions. Its also looks at key factors, first of which is sea-surface temperatures in the Atlantic.
“The die is cast for 2024,” said Phil Klotzbach, atmospheric researcher at Colorado State University, when looking at the current sea surface temperature in the Atlantic, and how those will create an active season. Even if the Atlantic warmed as slowly as it ever has into the peak of the season, the temperatures would be “top five” in terms of warmth. “1.5 degrees Celsius warmer than normal — that’s a big deal. That’s a lot of warmth.”
The numbers
The research team is forecasting 23 named storms.
The 1991 to 2020 average is 14.4, and the active 2023 Atlantic season saw 20 storms.
Eleven of those storms will likely reach hurricane strength, the report said, meaning winds of 74 mph or greater.
The 1991 to 2020 average is 7.2, and 2023 had seven.
And five of the hurricanes will likely reach major hurricane strength (Category 3, 4 and 5) with sustained winds of 111 mph or greater, they said.
The 1991 to 2020 average is 3.2, and 2023 had three.
Previously, the highest number of hurricane Colorado State ever predicted was nine, in 1995, which ended up with 11 hurricanes.
The Colorado team forecasts hurricane activity in 2024 will be quite high — about 170% of the average season from 1991 to 2020.
2023 clocked in at about 120% of the average season.
The report also includes the probability of major hurricanes making landfall.
It said the U.S. East Coast, including the Florida peninsula, had a 34% chance.
The average from 1880–2020 is 21%.
On the Gulf side from the Florida Panhandle to the Texas-Mexico border, the odds were 42%.
The average from 1880 to 2020 was 27%.
Another statistic the report focused on was the chances of a storm tracking within 50 miles of a given state.
Florida was the state that fared the worst in those forecasts. It had a 75% chance of a hurricane tracking within 50 miles of its coast. The 1880 to 2020 average was 56%.
And Florida had a 44% chance of a major hurricane tracking within 50 miles of its coast. The 1880 to 2020 average was 29%
Sea surface temperatures are at record warm levels this spring across most of the tropical and the eastern part of the subtropical Atlantic. This map shows anomaly rates above normal during late March, 2024. The hotter the color the higher the anomaly above the norm from1991 to 2020. (Courtesy Colorado State University)
The factors
The main factor in the prediction of an intense hurricane season, which runs from June 1 to Nov. 30, is the record warm tropical and eastern subtropical Atlantic sea surface temperatures this spring, said the report.
“I think what stands out the most about 2024 is just how warm the Atlantic is at present,” said project lead Phil Klotzbach of Colorado State University. “Even if the tropical Atlantic warmed at the lowest observed rate between now and the peak of the Atlantic hurricane season, it would still be one of the warmest tropical Atlantic hurricane seasons on record.”
This warm water has several ramifications.
Warm ocean waters act as fuel for hurricanes, therefore “a very warm Atlantic favors an above-average season.”
The high sea surface temperatures in the Atlantic also create a more unstable atmosphere, which hurricanes like.
Another ripple effect of the exceptionally warm water temperatures in the eastern, central tropical and subtropical Atlantic this spring is a weaker subtropical (Bermuda) high. That, in turn, means weaker trade winds. The less wind the more the water heats up. “These conditions will likely lead to a continuation of well above-average water temperatures in the tropical Atlantic for the peak of the 2024 Atlantic hurricane season,” said the report.
El Niño and La Niña
Forecasters are predicting that the El Niño that brought South Florida a relatively wet winter will mellow shortly, and is likely to shift to a La Niña by peak hurricane season, August through October.
La Niñas typically reduce wind shear over the Atlantic. Wind shear topples hurricanes, so La Niña, if it forms, may favor hurricane formation.
“Given the combined hurricane-favorable signals of an extremely warm Atlantic and a likely developing La Niña,” the report said, “the forecast team has higher-than-normal confidence for an April outlook that the 2024 Atlantic hurricane season will be very active.”
Klotzbach also reminded the public that we’re still a ways out from the start of the season, and later forecasts will be more accurate. “There’s still a lot that can change.”
