Colorado State University hurricane researchers predict an above-average Atlantic hurricane season in 2021, citing the likely absence of El Niño as the main factor.
The CSU Tropical Meteorology Project team predicts 17 named storms during the Atlantic hurricane season, which runs from June 1 to November 30. -5) with sustained winds of 111 miles per hour or more.
The team predicts that hurricane activity in 2021 will account for about 140% of the average season. In comparison, cyclone activity in 2020 represented around 170% of the average season. The 2020 hurricane season saw six continental U.S. hurricanes, including Category 4 Hurricane Laura that hit southwest Louisiana.
Tropical Atlantic sea surface temperatures are near their long-term averages, while subtropical Atlantic sea surface temperatures are much warmer than their long-term average values. The warmer subtropical Atlantic also favors an active hurricane season in Atlantic 2021.
The tropical Pacific currently has weak La Niña conditions, meaning water temperatures are a little cooler than normal in the eastern and central tropical Pacific. While those waters may warm up slightly over the next few months, CSU is not currently forecasting El Niño for the peak of the hurricane season in the Atlantic. El Niño tends to increase high-level westerly winds across the Caribbean into the tropical Atlantic, tearing hurricanes apart as they attempt to form.
While the tropical Atlantic currently has water temperatures near their long-term averages, the warmer-than-normal subtropical Atlantic generally forces a weaker subtropical high and associated weaker winds blowing across the Atlantic. tropical. These conditions then lead to warmer waters in the tropical Atlantic for the peak of the hurricane season in the Atlantic.
The team bases its forecasts on a statistical model, as well as on a model that uses a combination of statistical information and model results from the European Center for Medium-Range Weather Forecasts. These models are 40 years of historical hurricane seasons and assess conditions such as: Atlantic sea surface temperatures, sea level pressures, vertical wind shear levels (the change in direction and wind speed with height in the atmosphere), El Niño (warming waters in the central and eastern tropical Pacific) and other factors.
So far, the 2021 hurricane season has similar characteristics to those of 1996, 2001, 2008, 2011 and 2017.
“All of our analog seasons had above average cyclone activity in the Atlantic, with the 1996 and 2017 seasons being extremely active,” said Phil Klotzbach, researcher in the Department of Atmospheric Sciences and lead author of the report.
The CSU team will release forecast updates on June 3, July 8 and August 5.
Funding for this year’s report was provided by Interstate Restoration, Ironshore Insurance, Insurance Information Institute, Weatherboy and a grant from the G. Unger Vetlesen Foundation.
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