Forecast group predicts busiest hurricane season on record with 33 storms
“The unprecedented warmth in the tropical Atlantic right now — which we expect to persist through the hurricane season — is the dominant driving factor behind our prediction. While we don’t make a specific prediction for landfalling storms … an unusually active season in terms of basin-wide activity is likely to translate to an unusually active season in terms of landfalling storms.”
A research team led by University of Pennsylvania climate scientist Michael Mann is predicting the upcoming Atlantic hurricane season will produce the most named storms on record, fueled by exceptionally warm ocean waters and an expected shift from El Niño to La Niña. The new forecast, issued Wednesday, calls for a range of 27 to 39 named storms, with a best guess of 33. The most on record was 30 named storms in 2020.
The forecast is consistent with those recently released by Colorado State University and Accuweather but is even more aggressive.
“The unprecedented warmth in the tropical Atlantic right now — which we expect to persist through the hurricane season — is the dominant driving factor behind our prediction,” Mann said in an email. “While we don’t make a specific prediction for landfalling storms … an unusually active season in terms of basin-wide activity is likely to translate to an unusually active season in terms of landfalling storms.”
Ocean temperatures leaped into record-warm territory more than a year ago — linked to a combination of human-caused climate change and El Niño, and have remained there ever since, staying at a record high for 417 straight days.
Although El Niño boosts global ocean temperatures, it tends to produce wind patterns in the Atlantic that suppress tropical storm development. But ocean waters were so warm during the 2023 Atlantic hurricane season that there was an above-average number of storms nonetheless.
The National Oceanic and Atmospheric Administration
expects a marine heat wave, or sea surface temperatures well above normal, to continue in the tropical Atlantic through at least September. That has forecasters concerned about an active hurricane season because warmer ocean waters typically increase the intensity of storms.
Meanwhile, El Niño is forecast to transition to La Niña this summer. La Niña tends to have the opposite impact of El Niño on hurricane season — producing wind patterns that foster storm development in the Atlantic — further increasing the odds of an active season. If La Niña were to weaken toward the latter part of the hurricane season, then the forecast would decrease slightly to a range of 25 to 36 storms and a best guess of 31 storms, Mann’s research group said.
A tropical storm earns a name if its winds reach at least 39 mph. When winds climb to at least 74 mph, a tropical storm becomes a hurricane.
The forecast of 33 named storms is the most the University of Pennsylvania team has ever predicted. Led by Mann, who is famous for his “hockey stick” chart depicting a sudden rise in global temperatures over the last century, the research group has issued seasonal hurricane forecasts since 2009. The number of actual storms has been within its predicted range in 9 out of 15 outlooks.
Mann said that his team uses a different method than other groups that issue seasonal hurricane forecasts. “We are the only group that came even close (predicting as many as 24 named storms) to predicting the record 2020 season,” Mann said.
The Atlantic hurricane season officially runs from June 1 to Nov. 30, although storms sometimes form before or after those dates. Forecasters at the National Hurricane Center issued a special advisory Wednesday about a tropical swirl it is monitoring in the open Atlantic, but said it has only a 10 percent chance to develop into a tropical storm.
An average hurricane season produces about 14 named tropical storms, with about half becoming hurricanes.
Seven of the last eight hurricane seasons have featured above-average activity; the 2022 season was the only exception, and it had near-average activity. There have been at least 20 named storms in three of the past four seasons.