(TNS) - There’s only one name left on the National Hurricane Center’s alphabetical list of storm names. After Wilfred, it’s time for names left untouched since 2005: the Greek alphabet.
And with a good two months left in the formal hurricane season, it’s likely that Tropical Storm Alpha might make an appearance somewhere in the Atlantic before the season ends on Nov. 30. Although, as anyone around for the 2005 storm season remembers, the final storm of that season — Tropical Storm Zeta — actually petered out on Jan. 6, 2006.
So far, this hurricane season has already seen 20 named storms, enough to blow through nearly all of the names assigned to 2020. That’s still well within the National Oceanic and Atmospheric Administration’s prediction for a record-breaking season. In August, the agency said it expects up to 25 named storms, more than it has ever predicted in one season. Of those, NOAA predicted up to 11 would be hurricanes and up to six be major hurricanes.
The runner-up in the record books is 2005, when NOAA predicted there would be 21 named storms. That year there were 27 named storms, including six named after Greek letters.
“It looks like we’re on pace to give that one a run for its money,” said Brian Soden, a professor of atmospheric sciences at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.
But at this point in 2005, only nine storms had happened, and four of them were major hurricanes. So far this year, only one of the 20 storms was a major hurricane — Laura.
This season has broken records for the breakneck pace of storm naming, but it’s also above average in a metric meteorologists consider more important: accumulated cyclone energy. It accounts for intensity and duration of storms, and 2005 had the second most ACE of any hurricane season on record.
It’s too soon to tell how 2020 will stack up, as 90 percent of the year’s ACE is usually generated after Aug. 2. So far this season has only generated a little over a fifth of the ACE in 2005.
Why are there so many storms in 2020?
One factor could be technology. Satellites used to monitor storms have gotten much better, and so have the computers used to run the models that result in those “spaghetti” lines on a map.
“It turns out that about since the year 2000 we’ve been seeing, on average, about two to three more storms named early in the year. Many of them are weak or short-lived storms,” said Gerry Bell, lead hurricane season forecaster with NOAA’s Climate Prediction Center, in a media briefing in August announcing the prediction. “Prior to about 2000 we just weren’t able to see these storms as well.”
This season saw two storms form ahead of the season’s start and another form on the first day — June 1. It’s the sixth year in a row that storms have formed ahead of the official start of the season.
Louis Uccellini, director of the National Weather Service, was quick to counter the suggestion that the potentially record-breaking amount of storms this year could be attributed to technology alone.
“We have not changed the criteria for actually naming the storms, we just have better ways of identifying them earlier in the process,” he said at the August press conference.
The role of climate change
So could it be climate change?
“It’s not a simple question,” Bell said. “The writing is not on the wall on any of this, there’s a lot of research to do.”
Hurricane scientists have wrestled with climate change’s impact on tropical cyclones for decades. Two things are relatively clear, or in scientist speak, connections they have “high confidence” in. Rising temperatures and sea levels mean more storm surge and rainfall during storms, which can lead to the kind of historic flooding predicted for Hurricane Sally this week or, in a more dramatic example, seen in Hurricane Harvey in 2017.
“Other things like total numbers or speed of storms, we have less confidence in those changes,” Soden said.
The latest research from NOAA actually suggests that climate change will lead to fewer hurricanes by the end of the century, but of those storms, more will be powerful Category 3 or higher. And in the Atlantic specifically, that same study shows that other factors like aerosol pollution play a greater role than climate change.
Another seemingly clear connection is water surface temperature. As the planet warms, much of that excess heat is absorbed by the oceans. Besides killing coral and other marine life, hotter water fuels stronger storms.
This summer, NOAA records show that sea surface temperatures in the tropics are “much warmer than average.”
Enter La Niña
“Above-average ocean temperatures are likely playing a role in this year’s activity,” Bell wrote in an email to the Miami Herald. “However, other factors are also playing a role. As NOAA had predicted, these factors include weaker vertical wind shear, weaker trade winds, much more conducive wind patterns for hurricane formation coming off of Africa, and a stronger West African monsoon system.”
Last week, NOAA announced the formation of La Niña, a seasonal weather pattern that makes storm formation in the Atlantic more likely. Scientists saw this possibility coming in August and factored it into their prediction for the season.
La Niña is marked by cooler than average temperatures in the Pacific, which leads to less wind shear in the Atlantic. Wind shear helps curb the intensity of hurricanes.
But La Niña isn’t exactly rare. The last one was in the winter of 2017 and 2018, years where intense hurricanes made landfall in the U.S., including Hurricane Irma and Hurricane Michael.
So while La Niña can partially explain why 2020 is on track to break storm records, hurricane scientists like Soden say that the simplest answer is just that sometimes, every factor that influences hurricane formation just lines up perfectly.
“Because there’s so much year to year variability, it’s hard to define what’s unusual. Each year isn’t going to be like the average year,” he said. “This is an anomalous year.”
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