Unusual hurricane season nears end
Record 30 named storms formed in Atlantic; 12 hit U.S.
The 2020 Atlantic hurricane season had a record 30 named storms, and 12 of those hit the U.S. coastline.
Hurricane season ends Nov. 30 (that’s next week — fingers crossed there isn’t a Thanksgiving surprise), but the National Oceanic and Atmospheric Administration released its end-of-season roundup Tuesday.
“The 2020 Atlantic hurricane season ramped up quickly and broke records across the board,” Neil Jacobs, acting NOAA administrator, said in a news release.
There were a record nine named storms from May through July. Then 10 named storms formed in September, the most for any month on record. There was one point when five of these September storms were being monitored at the same time.
And on Sept. 18, Tropical Storm Wilfred exhausted the pre-selected 21 names for this season. For only the second time in history, the Greek alphabet was required to name subsequent storms.
“Everything just layered in the direction of enhancing and reinforcing each other,” said Matthew Rosencrans, a meteorologist at NOAA’s Climate Prediction Center, “to give those stronger storms and to give more storms.”
There were several layered conditions that supported the development of tropical storms or hurricanes. One is a warm phase of sea surface temperature in the North Atlantic. The sea’s surface temperature has cool and warm phases that may last 20 to 40 years, a natural occurrence that has been happening for at least 1,000 years. This current warm phase, which began in 1995, has favored more, stronger and longer-lasting storms.
Adding to this was a stronger west African monsoon. Disturbances that become tropical storms often come from Africa, and a stronger monsoon (with southwest winds from the Atlantic Ocean blowing into western Africa and more moisture being pulled in that direction) means these disturbances are better positioned to become tropical storms or hurricanes, Rosencrans said.
There was also weaker vertical wind shear and La Niña, both providing conditions more favorable for storms to develop whereas their opposites (strong vertical wind shear and El Niño) could have impeded storm development.
An average Atlantic hurricane season has 12 named storms, six hurricanes, and three major hurricanes (a Category 3 or above). This year had 30 named storms, 13 hurricanes and six major hurricanes.
This is the most storms on record, surpassing the 28 from 2005, and the second-highest number of hurricanes on record, according to the news release. The 12 storms that reached the continental U.S. broke a previous record of nine U.S. landfalls in 1916.
For storms that hit the U.S., Hurricane Laura was the strongest at landfall. It came ashore near Cameron, La., on Aug. 27 as a Category 4 hurricane with maximum sustained winds of 150 mph.
Nicaragua was also hit with two Category 4 storms: Hurricane Eta made landfall Nov. 3 with maximum sustained winds of 140 mph, and Hurricane Iota made landfall on Nov. 16 with maximum sustained winds near 155 mph. Iota was the strongest storm at landfall during the 2020 Atlantic season.
Warmer ocean and air temperatures, rising sea levels and other effects of climate change are expected to fuel stronger hurricanes. The flooding from storm surge could be higher, rainfall could be heavier and winds could be stronger.
Rosencrans said there will be studies to see if climate change contributed to this especially active hurricane season, which was the fifth consecutive year with an above-normal Atlantic season. But those studies haven’t been completed yet, and he re-emphasized the layering of multiple factors that fueled this hurricane season.
And as of noon Tuesday, the National Hurricane Center was tracking one disturbance in the Atlantic Ocean. Thankfully, it had only a 10 percent chance of developing into a tropical or subtropical cyclone within the next 48 hours.
But, it is 2020.