MIAMI — It was clear way back in mid-September, when the National Hurricane Center had already exhausted its regular list of names and turned to the Greek alphabet, that 2020 would be a hurricane season for the record books.
It definitely was that. The season, which formally ends every Nov. 30, produced a stunning 30 named storms — breaking the 2005 record of 28. It was only the second time forecasters resorted to the backup list of names and, as if to punctuate how wild a season it was, that first Greek-letter system, Tropical Storm Alpha, wound up hitting Portugal — the first recorded strike by a tropical system in that country’s history.
Though there was a lot of anxious monitoring of the storm-track cones, Florida’s only real brushes this year were Hurricane Sally, a Category 2 that struck the western Panhandle in September, and Tropical Storm Eta, whose zig-zagging path brought it over Central America, Cuba, South Florida and North Florida in the course of a week. Both storms brought destructive flooding to the Sunshine State, in some cases leaving neighborhoods in Miami-Dade and Broward counties underwater for days.
“The track map of 2020 is just insane when you look at it; the Caribbean and the Gulf were just plastered with storms,” said Phil Klotzbach, a meteorologist at Colorado State University. “Thankfully, given how many storms and how many landfalls there were, Florida made out pretty well.”
Other Gulf Coast states were not as lucky. Storm after storm entered the bathtub warm waters of the Gulf of Mexico and crashed into the northern Gulf Coast days later. A record-breaking five named storms made landfall in Louisiana, including Hurricane Laura, a deadly Category 4, and Hurricane Delta, a Category 2, six weeks later. The paths of the two storms were less than 15 miles apart.
And in Central America, the unprecedented back-to-back devastation of Hurricanes Eta and Iota crippled the region and left hundreds dead.
The eyebrow-raising number of storms could even grow a bit after the season’s formal end. Two systems wandering around harmlessly in the open Atlantic may yet gain strength and potentially, names. It all raises the question: Is 2020 a harbinger of things to come? So far, scientists say, they don’t see enough change in historical patterns to think so — and more sophisticated satellite monitoring of far-off systems may explain some share of the increased counts over the last few decades.
Still, there is wide agreement that climate change is sure to affect future storms in all kinds of ways — starting with making some of them wetter and stronger. Researchers don’t yet see enough evidence to suggest a warming world will mean a string of record-breaking years lies ahead.
Hurricane scientists said it’s too soon to say what next year may bring. The earliest official predictions don’t come out until the spring, so there’s a long way to go before experts can make an educated guess about the 2021 season
However, Klotzbach said the weather pattern that helped pushed 2020 to “hyperactive” status, La Niña, isn’t likely to stick around for next year. The opposite weather pattern, El Niño, has a dampening effect on storms.
“The odds of it being La Niña next year are fairly low, but also the odds of a strong El Niño are low,” he said. “If the Atlantic were to stay warmer than normal, we could see another above active season.”
This was the fifth consecutive year with an above-normal season, with 18 of the last 26 seasons also being abnormal. Scientists chalk that up to a long-running climate cycle known as the Atlantic Multi-Decadal Oscillation, which began in 1995. During these eras, which can last from 25 to 40 years, storm seasons are longer, stronger and more storm-packed.
“As we correctly predicted, an interrelated set of atmospheric and oceanic conditions linked to the warm AMO were again present this year. These included warmer-than-average Atlantic sea surface temperatures and a stronger west African monsoon, along with much weaker vertical wind shear and wind patterns coming off of Africa that were more favorable for storm development. These conditions, combined with La Niña, helped make this record-breaking, extremely active hurricane season possible,” Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, said in a statement.
Klotzbach also suggested that another weather pattern, the tropical upper tropospheric trough, might have played a role in keeping Florida and much of the Eastern Seaboard storm-free.
The mid-Atlantic trough was likely a little stronger than normal, he said, so it could have caused more wind shear than usual. Wind shear in the middle of the Atlantic makes it harder for storms that form off the coast of Africa to strengthen before they make it to the U.S. If they strengthen in the western Atlantic, they’re more likely to go toward the Caribbean and Gulf.
“If storms develop in the western Atlantic, there’s not many places they can go without hitting anyone,” Klotzbach said.
The tropics blew through [NOAA’s prediction](
Despite the damage and death dealt by these storms, 2020 doesn’t stack up historically when it comes to a metric called ACE, accumulated cyclonic energy. It’s a measure of intensity and duration of storms, and by that standard 2020 was only No. 6 in the historic record. The No. 1 spot is still held by 2005, when four powerful hurricanes crisscrossed and shredded Florida.
It’s also increasingly common for storms to form outside of the official storm season window, which runs from June 1 to the last day of November. This year, Tropical Storm Arthur [formed on May 16](
And of course, storms can happen after. In 2005, the last storm of the season dissolved in January of 2006.
During the final vice-presidential debate this year, Mike Pence correctly commented that there are no more storms now than there were a hundred years ago. In fact, a [NOAA study published this year](
Detangling the impact of climate change from the mess of factors that affect tropical cyclones is complicated work. Scientists are only confident in a few things, like that climate change will make future storms wetter.
“There’s a lot of things in climate we understand well. We understand there will be an increase in flooding, rainfall, storm surge and increased risk of compound flooding,” said Brian Soden, a professor of atmospheric sciences at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. Compound flooding is the combination of storm surge and rainfall, like South Florida saw with Tropical Storm Eta.
Other research, like the NOAA study, suggests that climate change makes storms more likely to be stronger. Soden noted that this was the fifth year in a row there’s been at least one Category 5 hurricane, a rare storm. Only about three dozen of the more than 240 hurricanes observed since the 1980s have gotten that strong, [according to Scientific American](
“A string of consecutive seasons with Category 5s, that’s something more consistent with what we’d expect in a warmer climate … as opposed to a higher number of storms,” he said.
This year’s Category 5 storm, Iota, reached that strength after a period of rapid intensification, which is when a storm gains at least 35 mph in wind speed in under 24 hours. Iota was the ninth storm this season to rapidly intensify, tying the seasonal record.
The process is difficult to forecast and tough to prepare for. In 2018, Hurricane Micheal leaped from a Category 2 to nearly a Category 5 in just 24 hours, catching Panhandle residents by surprise. It’s a phenomenon that could become more common with unrestrained global warming.
“There’s evidence and studies to support that as the climate warms, we’d see the likelihood increase of rapid intensification,” Soden said.
This season also saw a new study [published in the journal Nature](
“It’s just a single study,” Soden said.
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