The Atlantic hurricane season had produced no hurricanes through September 12, the latest point in the satellite era for the basin to remain without one. The season passed September 11 without a hurricane for the first time since reliable records began, extending an unusually quiet period well beyond the usual arrival date for the first Atlantic hurricane.
Modern satellite tracking began in 1966, and the Atlantic has never gone this late in a season without a hurricane during that period. The first Atlantic hurricane usually arrives by Aug. 11. By Sept. 10, the historical average is eight tropical storms and four hurricanes.
Five named tropical storms have formed in the Atlantic this season: Arthur, Bertha, Cristobal, Dolly and Edouard. Bertha and Edouard were the strongest, each reaching maximum sustained winds of 60 mph. A storm requires winds of 74 mph to be classified as a hurricane.
The main reason for the lack of hurricanes is El Niño, which has brought stronger wind shear across the Atlantic. Wind shear can disrupt the upward-moving convection that fuels tropical cyclones. This year, El Niño has sent hostile vertical wind shear through the Main Development Region, an area where Atlantic storms often develop.
The current El Niño is already at record strength for this time of year. Sea surface temperatures in the key El Niño monitoring region are approaching their highest values ever recorded, according to the information available to forecasters.
The effect is also reflected in accumulated cyclone energy, or ACE, a measure of storm activity and intensity over time. Atlantic ACE is running nearly 90 percent below average.
The absence of hurricanes has raised the prospect of a season with none at all. The last Atlantic season with no recorded hurricanes was in 1914. There were also no recorded hurricanes in 1907, although both seasons predated satellite monitoring and storms that stayed over open water could have gone undetected. No hurricane-free Atlantic season has occurred during the satellite era.
AccuWeather meteorologist Alex Sosnowski has said a hurricane-free season is possible under the record El Niño conditions.
There remains uncertainty over whether a hurricane will form before the season ends. Forecasters have identified potential for activity around the western Caribbean near the week of September 20, though it is unclear whether any system there would reach hurricane strength.
Atlantic quiet has coincided with intense activity in the Pacific. Three hurricanes were active there simultaneously last week, including Hurricane Lowell, a Category 5 storm that weakened before striking Hawaii. El Niño can suppress development in the Atlantic while supporting powerful Pacific storms.
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