It’s official: 2020 now has the most named storms recorded in the Atlantic in a single year.
On November 9, a tropical disturbance occurring in the northeast Atlantic Ocean gained enough strength to become a subtropical storm. In this way, Theta became storm number 29 of the year, surpassing the 28 that formed in 2005.
With sustained maximum winds of about 110 kilometers per hour from November 10, Theta is expected to stir the open ocean for several days. It’s too early to predict Theta’s final strength and trajectory, but National Oceanic and Atmospheric Administration forecasts say they expect the storm to weaken later in the week.
If so, like most of this year’s storms, Theta probably won’t become a major hurricane. That trajectory may be the most surprising of this season: there was a record number of storms, but overall they were relatively weak. Only five (Laura, Teddy, Delta, Epsilon, and Eta) became major hurricanes with winds exceeding 178 miles per hour, although only Laura and Eta touched land near the peak of their strength as Category 4 storms.
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Still, the 2020 hurricane season started fast, with the first nine storms arriving before ever (SN: 9/7/20). And the season has been the busiest since the name began in 1953, thanks to warmer-than-usual water in the Atlantic and the arrival of La Niña, a cooling-off period that occurs regularly in the Pacific, affecting winds in the Atlantic. and helps form hurricanes (SN: 21/09/19). If a swirling storm reaches wind speeds of 63 miles per hour, it gets a name from a list of 21 default names. When that list runs out, the storm gets a Greek letter.
Although wind patterns and warm Atlantic water temperatures set the stage for the chain of storms, it is unclear whether climate change plays a role in the amount of storms. As the weather warms, I would expect to see more destructive high-grade storms, says Kerry Emanuel, an atmospheric scientist at MIT. "And this year is not a poster for that." So far, no storm in 2020 has been stronger than a Category 4. The 2005 season had several Category 5 storms, including Hurricane Katrina (SN: 20/12/05).
Emanuel says there is a lot of energy in the ocean and atmosphere this year, including unusually warm water. "The fuel supply could make a storm much stronger than we've seen," says Emanuel, "so the question is, what keeps many storms from living up to their potential?"
An important factor is wind shear, a change in wind speed or direction at different altitudes. The wind shear "doesn't look like a lot of storms have stopped forming this year," Emanuel says, "but it prevents them from being too intense." Hurricanes can also create their own wind cut, so when several hurricanes form very close together, they can weaken each other, Emanuel says. And sometimes this year, several storms occupied the Atlantic simultaneously; on September 14, five storms spun at once.
It’s unclear whether watching hurricane season run with the Greek alphabet is a “new normal,” Emanuel says. The historical record, especially before the 1950s, is erratic, he says, so it’s hard to put this year’s record season in context. It is possible that there were so many storms before the names began in the 1950s, but that only large and destructive ones were recorded or noticed. Now, of course, forecasters have the technology to spot them all, “so I wouldn’t be too bent out of shape this season,” Emanuel says.
Some experts are hesitant to use the term “new normal”.
“People talk about the‘ new normal ’and I don’t think that’s a good phrase,” says James Done, an atmospheric scientist at Boulder’s National Center for Atmospheric Research, Colo. "It involves some new steady state. We are certainly not in a stable state; things are always changing."