Consensus building for below-average hurricane season, but signals mixed

The 2023 Atlantic Hurricane season is lining up to deliver below average storm and hurricane counts vis-a-vis the 30-year average, analysts at Colorado State University’s Tropical Weather & Climate Research department have said in their first look at the season.

“We’re talking a little bit below the recent average,” the report's chief author Philip Klotzbach said in announcing the forecast.

Klotzbach warns on the vagaries of early season forecasting, with humility for the public's practised focus on the first forecasts available.

“The April forecast gets the most attention and that's the one that has the lowest level of skill,” he warned.

The full swathe of forecasts run at mostly double-digit percentage gaps to the 30-year average. On the bottom line, CSU anticipates 13 named storms (14.4 average), 6 hurricanes (7.2) of which 2 will be major category 3, 4 or 5 (3.2).

Measured by accumulated storm energy, the forecast for a 100 seasonal reading is nearly 19% below the 123 30-year average.

But landfall probabilities in the early view are not below the historic average. CSU sees a 44% of major hurricane landfall on US coastline, a 22% chance of an east coast landfall and a 28% chance of a Gulf coast landfall, all within 1 percentage point of 140-year averages.

Expectations for a shift to “a really, really robust El Niño event” seem to set the overriding tone, even overriding contrarian signals.

The statistical models underpinning CSU work chiefly pointed to higher forecasts, often on account of higher than normal water temperatures in the Atlantic, which CSU discounted “out of respect for fact that we could get a really robust El Niño event,” Klotzbach said.

The CSU forecast is a pretty good match to predictions out just April 6 from researchers at the UK government-supported research venture Tropical Storm Risk (TSR).

IN its early-season view, TSR is calling for 12 tropical storms in 2023, including six hurricanes of which 2 may achieve intense status.

The accumulated storm energy reading from TSR of 84, however, fell notably below the 100 now predicted by CSU.

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