After dire predictions for an above-normal hurricane season, conditions in the Atlantic have calmed down eerily in recent weeks.
The last time the Atlantic spawned a named storm was between Aug. 13 and Sept. 3 in 1968 — more than 50 years ago, according to a new report by Colorado State University researchers. It was also the first Labor Day holiday weekend without a named storm in 27 years.
“This prominent (quiet) period is particularly notable given that it coincides with a time of year when the Atlantic is climatologically very busy,” the report said.
The reassurance comes after federal officials warned of an 85 percent chance of above-normal hurricane activity in the Atlantic, with up to 25 named storms this year. There have been five named storms so far, three of which have become devastating hurricanes: Beryl, Debby and Ernesto.
Aggressive and impactful reporting on climate change, the environment, health and science.
But experts say it’s too early to call the season over and warn that storm activity is likely to increase in the coming weeks. The Atlantic hurricane season runs from June 1 to November 30.
“We’re a little behind where we should be with five named storms to date,” said Dan Harnos, a meteorologist at the National Oceanic and Atmospheric Administration’s Climate Prediction Center. But “the typical peak of the season isn’t until Sept. 10, and there’s historically been more hurricane activity after the peak than before.”
In fact, it’s more common for the second half of the season to see significantly more activity than the first, with August, September and October contributing to 90% of the season’s activity, according to the National Hurricane Center. In 2022, eight hurricanes occurred after September 1.
Still, the reasons for the recent lull are somewhat puzzling.
David Zierden, Florida State Climatologist, said a number of factors could be at play, including the delayed onset of La Niña, shifting monsoon patterns in West Africa and Saharan dust activity.
La Niña, a climate pattern in the tropical Pacific that helps drive weather around the world, was a major factor in the early season outlook. That’s because it tends to reduce wind shear in the tropics, which allows hurricanes to grow in strength and keeps the water in the Atlantic Ocean warm, which helps fuel storms.
But La Niña has developed more slowly than originally expected and is now not expected to emerge until this fall.
A woman paddles a boat down a street in Baltimore after Hurricane Debby in early August.
(Kaitlin Newman/Baltimore Banner via Associated Press)
“There’s still a 60% to 70% chance that it will develop and be in place for the rest of our hurricane season, so that still seems to be a factor that would point to a more active season along with near-record and record-high sea surface content and of ocean heat,” said Zierden, who is also a research associate at Florida State University.
And while the wet season in West Africa has been active this year, it has been pushed further north than usual for reasons that are not yet entirely clear, Zierden said. For this reason, the disturbances that come from Africa are directed into drier air and less favorable sea surface temperatures for hurricane formation. As a result, the storms “don’t really develop like they would if they got out of that more southerly path.”
Saharan dust is also a mitigating factor because it makes the atmosphere drier, more stable, and less prone to hurricane formation. Dust is usually a big player earlier in the season, but this year its activity stretched into August, which may have contributed to the slowdown.
But there are other factors that could still spell trouble — namely, warm ocean temperatures across much of the Atlantic basin, which can provide more energy to fuel storm development. Sea surface temperatures in 2023 far exceeded any previous year on record, and this year was similarly hot, and in some cases even surpassed it.
“It’s part of an overall trend of warming oceans and warming sea surface temperatures that can be attributed to climate change and anthropogenic warming,” Zierden said.
Even so, warmer waters don’t necessarily mean that all the ingredients that go into tropical cyclone formation will be favorable in a warming climate, he said, meaning the total number of tropical cyclones worldwide may not change much.
However, the potential for stronger storms is increasing, as evidenced by Beryl, which became the oldest Category 5 Atlantic hurricane on record when it formed in late June.
The storm bore down on parts of the Caribbean and the Gulf Coast and was associated with at least 36 dead in Texas, flooding highways and knocking out power to more than 2.5 million people.
Hurricane Debby hit Florida’s west coast in early August, also causing high winds and widespread flooding. The last storm, Ernesto, formed on August 12 and continued pummel Puerto Rico and Bermuda.
For that reason, Zierden said, “We should not let our guard down or breathe a sigh of relief.”
“My main concern is not that we’re going to catch up and hit the number of storms that are predicted — it’s that of the ones that do form, one or more have the potential, with these very warm sea surface temperatures in the Gulf of Mexico. and the Caribbean to be very strong, damaging and even deadly storms,” he said. “That’s still on the table as we enter the height of the Atlantic hurricane season.”
He’s not alone in saying the season may not hit the expected number of storms.
A recent lull in this activity prompted AccuWeather, a private weather forecasting website, to lower its seasonal forecast to 16 to 20 named storms; six to ten hurricanes; three to six major hurricanes; and four to six direct impacts on the United States.
“Our team integrated the latest data and insights while monitoring the unusual conditions that hindered the development of tropical storms and hurricanes last month,” AccuWeather Chief Meteorologist Jon Porter said in a statement about the downgrade.
A man in Plainfield, Vt., surveys the damage after Hurricane Beryl in July.
(Charles Krupa/Associated Press)
But Porter noted that the season has already been damaging, with preliminary estimates putting as much as $32 billion in U.S. economic losses from Hurricane Beryl and $28 billion from Hurricane Debby.
“We don’t want anyone to let their guard down, even though we are now forecasting fewer storms overall,” Porter said, adding that ocean waters are still incredibly warm near many of the nation’s coastal cities. “It only takes one strong hurricane or slow-moving tropical storm to endanger lives and cause destruction.”
NOAA officials declined to comment on AccuWeather’s updated forecast, but said their Climate Prediction Center’s Aug. 8 outlook will be its final release for the season.
The outlook showed minimal changes from the agency’s first outlook issued in May, calling for up to 24 named storms, 13 hurricanes and seven major hurricanes.
The outlook for the Pacific basin, which saw a rare storm in Hurricane Hilary last year, also remains unchanged with a 60% chance of a below-normal season.
But even though the hurricane season officially ends on Nov. 30, there are signs that tropical storms could continue to form in the Atlantic until December, said Erica Grow Cei, a meteorologist and spokeswoman for the National Weather Service.
“This is due to the expected onset of La Niña, which suppresses the wind shear, and the anomalous persistent warmth that is expected to remain in the tropical Atlantic and Caribbean,” Grow Cei said.
Accumulated Cyclone Energy – NOAA’s measure of overall activity – is also still running well above normal thanks to contributions from Beryl, Debby and Ernest.
“The hurricane season got off to an early and violent start with Hurricane Beryl, the oldest Category 5 Atlantic hurricane on record,” NOAA Administrator Rick Spinrad said in the agency’s August update.
“The update to NOAA’s seasonal hurricane outlook is an important reminder that the height of the hurricane season is just around the corner,” he said, “when the most historically significant hurricane and tropical storm impacts tend to occur.”
