Several high-profile forecast groups – including the pioneers of seasonal hurricane forecasting at Colorado State University – issued their final hurricane season outlooks this week ahead of what’s typically the Atlantic’s busiest stretch.
Despite a budding El Niño in the eastern Pacific – an event that typically softens Atlantic hurricane activity – experts continue to take the over, calling for above-average tropical activity for August, September, and October.
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Though seasonal forecasts can’t tell us when or where a storm may strike – a crucial missing link that limits their utility – more active hurricane seasons tend to favor increased landfalls, so if forecasts materialize, it could mean heightened landfall risks.
The high numbers are predicated on record warmth throughout the tropical Atlantic. In their report released on Thursday, experts at Colorado State University noted the historic nature of the ongoing ocean heat wave, with waters across the Atlantic main development region in 2023 eclipsing the typical temperatures of our most extreme hurricane seasons.
While sea surface temperatures are only one factor at play, they are a top predictor for overall hurricane season activity – especially at such levels – because they can alter large-scale atmospheric circulations and promote a more conducive environment for hurricane activity.
Wind shear, the other main hurricane season predictor, was only slightly above average in July, indicating that at least for now the Atlantic warmth is winning out over the usual taming influence of El Niño.
The UK Met Office – the national weather service for Great Britain and Northern Ireland – issued their August hurricane outlook update on Tuesday. The forecast is in line with their previous May forecast, calling for an extremely active hurricane season with still 8 hurricanes left to form this season.
Colorado State University in their August update on Thursday was similarly aggressive and calls for a total of 9 hurricanes, with 4 strengthening into Category 3 or stronger hurricanes. Both groups predict overall activity running 140-170% above the 1991-2020 average.
NOAA, the parent agency of the National Weather Service, will issue its final hurricane season outlook next Thursday morning.
Despite the ominous forecasts, the Atlantic will remain mostly quiet for the near term. As we discussed yesterday, a robust tropical wave moving through the eastern Atlantic, flanked by two other disturbances, has a healthy appearance on satellite, but forecast models are bearish on its development in the days ahead.
We’ll want to monitor these disturbances – in particular the middlemost wave – as they get farther west next week, but for the time being, none is an immediate concern.