Hurricane expert shares sneak peek into forecast process month ahead of inaugural tropical outlook
Dr. Phil Klotzbach with Colorado State University plans to release the 2025 hurricane season outlook on Thursday, April 3. Klotzbach said he started preparing for the upcoming season before 2024 was over.
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With coastal residents just three months away from preparing for the upcoming hurricane season, some experts are well underway with planning, with some efforts that started before the previous season was finished.
Dr. Phil Klotzbach, a renowned hurricane specialist at Colorado State University, is known for his annual tropical weather outlooks that are issued during the spring and summer.
Klotzbach told FOX Weather that while CSU’s first outlook of the year will be released on Thursday, April 3, he began mentally preparing months ago.
"Honestly, I would say that we start thinking about the upcoming hurricane season before the previous season even ends," he said. "We spend extensive time during the offseason reviewing our current modeling framework and potentially incorporating additional predictors."
A key component of the upcoming forecast will be model guidance from the European Centre for Medium-Range Weather Forecasts (ECMWF), the UK Met Office and the Japan Meteorological Agency, which all serve as a bedrock in the hurricane outlook.
Once sufficient model data is available, the hurricane expert explained that statistical models are then run to provide CSU with an idea of global weather features. The process is usually completed by around March 20, giving forecasters roughly a week or two to finalize the hurricane season outlook before its public release.
A complex formula
The statistical models don’t give forecasters an easy printout, such as 14 named storms, 7 hurricanes and 3 major hurricanes – which are average season totals. Instead, they offer a sense of the Accumulated Cyclone Energy, which then the CSU team builds the outlook from. ACE is calculated using a complex formula that takes into account each tropical cyclone’s maximum sustained wind speed and duration.
The April outlook is usually made up of dozens of pages, which outline everything from the probability of a strike to the expected numbers of cyclones and even why forecasters believe the season will either be inactive or active.
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The greatest number of named storms ever expected in an April outlook was last season's 23, while the lowest was 7, which was called for in 2015.
The tradition of releasing an outlook was started by the late Dr. Bill Gray in 1984 has become the gold standard in weather forecasting.
Some years, outlooks are more accurate than others, as both known and hidden factors play a role in seasonal activity.
In 2024, CSU forecast 23 named storms, with 11 hurricanes and 5 reaching at least Category 3 status. While the number of hurricanes and major cyclones was accurate, the prediction of named storms would get a grade of C+ on a traditional grade school scale, as there were 18.
However, CSU's forecast was more accurate than many others, with Penn State University even expecting between 27 and 39 tropical cyclones, nearly double what actually occurred.
2024 hurricane season summary
(FOX Weather)
In addition to issuing this year’s outlook, Klotzbach is still reflecting on last year, with some theories he hopes to publish soon regarding why part of the 2024 season went awry, including an unexpected extended absence of tropical cyclones during the heart of the summer months.
"We're trying to better understand why the lull took place and, of course, see if we could have predicted it," Klotzbach stated. "I’m not sure there’s much we could have seen with our early outlooks, but I think we may be able to incorporate some Saharan dust data to help with the August forecast."
A pattern forecasters have observed is that the second half of recent hurricane seasons tends to be much busier than the first, something CSU attributes to the status of the El Niño Southern Oscillation, rather than something like climate change.
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The ENSO is currently in flux, which means there may be more uncertainty in the initial hurricane outlooks this year due to what its status will be from June through November.
Klotzbach said he’s fairly confident that the year won’t be dominated by an El Niño, as strong trade winds across the Pacific will prevent warmer waters from accumulating for several weeks.
A surprising change across parts of the Atlantic is that tropical waters aren’t as warm as the lofty record temperatures they reached over the past two years, which will be an important factor in the 2025 hurricane season outlook.
2025 Hurricane Season Names
(FOX Weather)
The first named storm of the 2025 Atlantic hurricane season will be Andrea, followed by Barry, Chantal and Dexter. The name Dexter replaces Dorian, which was retired after the 2019 season.