US researchers raise prediction on named storms in 2021 Atlantic hurricane season

HOUSTON (ICIS)–Hurricane researchers at Colorado State University (CSU) raised their prediction on the number of named storms expected during the 2021 Atlantic hurricane season, which began on Tuesday and runs through 30 November.

The CSU Tropical Meteorology Project team is now predicting 18 named storms in 2021, including Ana, which formed in May in the Atlantic. Ana made it seven consecutive years where the first storm of the season formed prior to 1 June.

The team predicted 17 named storms in its initial prediction in early April, mainly because of the absence of El Nino.  El Nino tends to increase upper-level westerly winds across the Caribbean into the tropical Atlantic, tearing apart hurricanes as they try to form.

Also, 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.

CSU researchers predict eight of the named storms to become hurricanes, and four to reach major hurricane strength.

According to the Saffir-Simpson index, a storm reaches hurricane strength when sustained winds reach 74 miles/hour.

The team, which bases its forecasts on a statistical model, as well as two models that use a combination of statistical information and forecasts from dynamical models from the UK Met Office and the European Centre for Medium-Range Weather Forecasts, predicts that 2021 hurricane activity will be about 120% of the average season.

By comparison, 2020’s hurricane activity was about 145% of the average season.

The team said that the early part of the current season is exhibiting characteristics similar to 1996, 2001, 2006, 2008, 2011 and 2017.

“1996, 2008 and 2017 had above-average activity, 2001 and 2011 had near-average activity, and 2006 had slightly below-average activity,” said Phil Klotzbach, research scientist in the Department of Atmospheric Science and lead author of the report.

The CSU team will issue forecast updates on 8 July and 5 August.

The report also includes the probability of major hurricanes making landfall:

• 69% for the entire US coastline (average for the last century is 52%)
• 45% for the US Atlantic coast including the Florida peninsula (average for the last century is 31%)
• 44% for the US Gulf coast from the Florida panhandle westward to Brownsville (average for the last century is 30%)
• 58% for the Caribbean (average for the last century is 42%)

Additional reporting by Stefan Baumgarten and Al Greenwood

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