The 2020 hurricane season is coming to a close, but it's one for the record books — leaving prior benchmarks far behind in the statistics-heavy field of tropical meteorology.
This year saw earlier-than-usual storms, storms that grew stronger later in the year and way more storms, period. The season wasn't just notable for its records, either, with a high human cost as some storm victims were repeatedly ravaged: two unfortunate stretches of coastline were hit multiple times, weeks or even days apart.
It's an exceptional season that will officially close Nov. 30. While it is possible for cyclones to spin up any time of the year, and possible that this hyperactive season won't obey its end date, it's still a good time to stop and take stock of a remarkable six months.
That brings us to the first of several numbers that explains the 2020 hurricane season, so far:
30 named storms
From Arthur in May to Iota in November, there have been an astounding 30 named storms this year, past the previous record of 28 named storms in 2005. They've come earlier, too; the 2005 spate of cyclones stretched into January of the following year, so this season has spit out storms months ahead of schedule.
For comparison, there were an average of roughly 12 storms a year from 1981 to 2010. The sheer volume of tropical storms and hurricanes has, as usual, raised the question of whether climate change is making more cyclones form.
Jim Kossin, an expert on hurricanes and the warming planet who works for the National Oceanic and Atmospheric Administration, said it's a bad idea to pin long-term climate trends to a single year. And while the Atlantic has been relatively more active for the past few decades, there's disagreement about whether that's because of a warming planet, a natural cycle, another factor entirely or a combination of variables.
For example, he said, one theory suggests that reductions in smog and other industrial emissions since the 1970s has let more sunlight hit the Atlantic, warming it more than other parts of the globe and encouraging more storm development there.
But in some cases, the connections are clear: abnormally warm ocean waters made storm formation easier at some points in the season.
9 Greek names
The typical list of names for tropical cyclones, determined every year by the World Meteorological Organization, runs just 21 names long (the group says it's too hard to find enough names that start with Q, U, X, Y and Z). So the surplus list, the letters of the Greek alphabet, comes into play in particularly active years like this one.
So far, nine of those names have been used, and some of those storms have been particularly devastating. That's raised a new question for the WMO: should Greek names given to particularly destructive storms be retired — or not used again in future years — like names on the normal list are? Meteorologists are pushing for this to happen in the future, according to the Washington Post's Capital Weather Gang.
In one example, after Category 4 Hurricane Laura slammed into Cameron, La., in late August, the Greek-named Hurricane Delta hit near Creole, La. — around 13 miles away — just over a month later.
Delta was remarkable in other ways, too. It was the fourth storm to hit Louisiana, and then the record-breaking 10th to hit the United States, in a single season. Since then, there have been two more U.S. hits, bringing the total to 12.
13 days apart
While Laura and Delta hit the Bayou State with a one-two punch, a different pair of storms dealt even worse damage to Central America.
First, Hurricane Eta smacked into Puerto Cabezas, Nicaragua, as a Category 4 on Nov. 3. Then, just 13 days later, Hurricane Iota hit 15 miles to the south on the country's coast, also as a Category 4 storm. Combined, they caused hundreds of deaths. Iota alone sent an estimated 40,000 people to shelters, according to the New York Times.
Damage from the second storm was particularly devastating in Colombia's Providencia Island, a few hundred miles off the coast of Nicaragua, where the local hospital and thousands of homes were mowed down by the then-Category 5 storm.
5 cases of "rapid intensification."
Five cyclones so far this year have met the Hurricane Center's definition of "rapid intensification," or their winds blowing at least 35 mph faster in just a 24-hour period. Eta and Iota are possibly the most dramatic examples.
A gap in hurricane hunter flights, which measure the winds inside of storms, mean meteorologists may never know for sure just how strong Eta was before landfall, the Washington Post reported. Still, the speed at which the storms exploded in strength is remarkable: Eta reached Category 4 strength just four days after forming. Iota followed a similar schedule, though its peak was more dramatic: the storm reached Category 1 strength on Nov. 15, and just 33 hours later it was spinning as a Category 5 hurricane with 160 mph winds. It was the latest-ever Category 5 hurricane recorded in the Atlantic basin, according to the National Hurricane Center.
Rapid intensification is one effect on hurricanes that some scientists, including Kossin of NOAA, link to climate change. Another example was 2019's Hurricane Dorian, which grew in strength dramatically before landing in the Bahamas, and then showed another effect that is linked to a warming planet: it stalled over the islands completely.
2 storms in South Carolina
South Carolina, which had been swamped in the past five years by a series of serious tropical cyclones, was relatively lucky this year.
Only two storms had a direct trajectory for the state: Tropical Storm Bertha, which was named as it was washing over the Lowcountry in late May. And Hurricane Isaias, which stayed just offshore from the Lowcountry before speeding ashore in the Grand Strand as a weak Category 1, flooding the low-lying Cherry Grove area and sweeping sand off the area's beaches. While the storm made a mess of the area, it had a far less severe impact than other recent storms, like Matthew in 2016 or Florence in 2018.