Hurricane season likely to be 'very active'
"A very active" hurricane season is likely this year, but that does not necessarily mean that the re/insurance industry will face high losses, according to the Verisk extreme events solutions team.
Verisk senior scientist Wesley Terwey said in an overview of the 2024 seasonal forecasts, said record sea surface temperatures (SST), the effects of La Nina and a near record Atlantic Meridional Mode (AMM) all point to a very active hurricane season, with a consensus prediction of 20 to 25 named storms, 10 to 12 hurricanes and five to seven major hurricanes. Most forecasters have cautioned that they expect to revise their forecasts int he weeks and months ahead.
This year's forecast comes on the heels of a relatively benign 2023, when the El Nino effect dampened the effect of record SSTs, but it was notable for the rapid intensification of several major hurricanes, including Lee and Otis, he said.
“The science seems to be pointing towards a very active Atlantic season,” Terwey told a webinar audience of the “general consensus” of early forecasts out to date.
Forecasts for seasonal accumulated storm energy (ACE), a catch-all metric capturing storm frequency, strength and duration, run “well above average” in a range of 150 to 240.
But that’s a poor indicator of insured storm losses, Terwey said.
“The correlation between activity and landfalls is fairly good, but the correlation between activity and losses is not perfect,” he said. He cites three years with ACE in a tight range of 165 to 180 (2003, 2010 and 2020) but losses in a range of $7 billion to $50 billion. 2005, the year of Katrina, came in at $260 billion.
“For any one season it only takes one storm,” he said. “All we can best say is that it has a higher chance of happening.”
The science leading to the early-season activity forecasts is not the full picture behind the season to come, he said.
La Nina, high SSTs and a positive AMM “can usually only explain about 2/3” of the eventual storm development story, he said. How they will interplay with local and temporary or shifting factors like the dry-air and dust creating Saharan Air Layer or the shifting circulation patterns of the Madden-Julian Oscillation are yet to be seen.
Sea surface temperatures, in fact, are breaking sufficiently away from known trend to possibly question the models overall.
“With some unprecedented sea temperatures in the Atlantic, there is likely to be a large amount of range in these forecasts,” Terwey said. “Be sceptical of anyone who ‘guarantees’ that this season will be record-breaking.”
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