The 2024 Atlantic may be high activity, need not be high loss: Verisk
The North Atlantic may indeed whip up a highly active hurricane season in 2024, but key variables remain in play and activity need not lead a straight line to high insured losses, Wesley Terwey from the Verisk extreme event solutions team said in an overview to 2024 seasonal forecasts to date.
“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. The more headline-grabbing forecast for major hurricane count runs 5 to 7.
But that’s a poor indicator of insured storm losses, Terwey adds. “The correlation between activity and landfalls is fairly good, but the correlation between activity and losses is not perfect,” he says in understatement. 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. Then 2005 comes swinging in at $260 billion.
“For any one season it only takes one storm,” he says of age-old wisdom. “All we can best say is that it has a higher chance of happening.”
And the science leading to the early-season activity forecasts is not the full picture behind the season to come, he further notes.
Yes, ENSO conditions are shifting into neutral or even a light storm-supportive La Nina. And yes, storm-supportive Atlantic surface sea temperatures are much higher than at the same point in the already record-smashing 2023 season.
But those two major seasonal factors, core to every early-season forecast, “can usually only explain about 2/3” of the eventual storm development story. 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 skeptical of anyone who ‘guarantees’ that this season will be record-breaking.”
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