2023 hurricane season in flux: CSU ups forecast by a quarter again

The Atlantic hurricane season is a wildcard, with analysts at Colorado State University yet again hiking their forecasts for storm activity in a wavering tug-of-war between storm supportive Atlantic sea temperatures and storm suppressive El Niño conditions.

The “extreme anomalous warmth” of Atlantic surface temperatures look sufficient to trump the storm-suppressive wind shear expected to develop from 2023’s shift to El Niño, authors are now suggesting.

The upshot: CSU upped its full swathe of forecasts for the season, most by neighbourhood 20-30% from estimates released just one month ago and now expects an “above normal” hurricane season.

It’s the second consecutive upgrade from CSU which started the year expecting the shift to El Niño could secure a milder than average season. Taken against forecasts from mid-April, most metrics are up 40-60%.

It’s a tough year for forecasters, with all major hurricane forecast centres admitting to feeling caught between the pull of the opposing factors.

Those conditions are rather “unprecedented” and CSU analysts can't lean much on history. “There are no great analogues for the current and projected situation of a moderate to strong El Niño combined with a record warm Atlantic.”

For the July update, still burdened with “larger than normal” uncertainty, CSU upped its forecast for the key metric of accumulated cyclone energy by another 28% to a measure of 160, now 30% over the long-term average. CSU had started the season expecting a tally 19% below average.

The forecast tropical storm count has been hiked by another three to 18, now notably above the 14.4 long-term average.

The likely hurricane count is up by another two, now to nine versus the 7.2 longer-term average and may now include 4 major hurricanes for the season, CSU said.

CSU gives a 50% chance that at least one of those major hurricanes will hit the US coastline, with probabilities lightly tipped towards the Gulf coast.

The full array of models used by CSU offer a range on 2023 forecasts from a “slightly above-average” season to “an extremely active season.” The final forecast is “slightly” below the average of those forecasts on account of a lingering bet on El Niño.

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