Tropical Storm Gabrielle lasted all of 12 hours before largely fizzling on Thursday, the latest in a welcome but entirely unexpected string of duds fired out by the tropics.
Hurricane season 2013, approaching the historic peak of activity early next week, has produced zero actual hurricanes so far.
If that trend continues another week — and it could with the National Hurricane Center monitoring four iffy systems — it would mark the quietest start to the Atlantic hurricane season in nearly a half-century. Since 1967 and the dawn of satellite tracking, the latest date for a first hurricane to form was Gustav on Sept. 11, 2002.
“We’ve had seven named storms but they’ve been little, very weak systems, really nothing,” said William Gray, a Colorado State University climatologist who pioneered the science of seasonal hurricane forecasting.
Those pre-season projections have become increasingly accurate but they have missed the mark to date. Gray and colleague Phil Klotzbach had forecast 18 named storms with nine hurricanes and four major storms this year. A host of university and government experts had expected roughly similar numbers and another active season.
“Everybody is pretty well busted,” said Gray, with a chuckle. “The atmosphere is a very difficult thing to predict. You can predict a lot of it but there are some things that happen that defy our best knowledge and this looks like it’s one of those seasons.’’
The most obvious X factor this year appears to be dry air, a combination of dust clouds swirling from Africa’s Sahara Desert and dry, sinking air over the open Atlantic, said NHC spokesman Dennis Feltgen. Tropical Storms Chantal, Dorian and Erin all passed through it, emerging gasping for life.
“It just disintegrated those storms,’’ he said.
Gabrielle, which forecasters expect to dissolve into an open wave after crossing Hispaniola late Thursday, also appeared to struggle with dry air. But it may also have been crippled by a large trailing wave, which appeared to have absorbed much of its energy, “decoupling’’ the mass of storms from its low-level center of circulation.
Other influences also may be tamping down storms, including strong upper level winds in the Gulf of Mexico and the Caribbean that have shredded some developing systems.
Still, Gray and other atmospheric scientists are puzzled. Most everything else in the tropics appears ready to prime the pump. Ocean temperatures are running above average. There is no global El Niño pattern that typically increases wind shear and inhibits development. More recently, a shift in pressure called the Madden-Julian oscillation has set in, which increases atmospheric instability that typically fuel hurricane formation.
“The conditions have been favorable for storms. They just haven’t generated,’’ said Tim LaRow, an associate research scientist at Florida State University’s Center for Ocean-Atmospheric Prediction Studies. “I don’t think the research community has a good answer yet.”
Counting named systems alone, it’s still been an active year — with Gabrielle, the seventh storm, forming on Sept. 4. In the average year, the seventh storm arrives 10 days later on Sept. 14.
But the first hurricane typically arrives by Aug. 10.
Feltgen said first hurricanes in September are unusual but not unprecedented. Records dating to 1851 show 15 years when the first hurricane formed after Sept. 5. The all-time latest came on Oct. 8, 1905.
Of course, forecasters also stress that the tropics are a lot like the stock market: Past performance is not necessarily an indication of future results.
While Sept. 10 marks the historic height of the season, there are still more than two potentially active months left. In 2001, Hurricane Erin didn’t form until Sept. 9. Eight more hurricanes would follow, including four major ones. The next year, late-forming Gustav was joined by three more hurricanes, including two major ones.
The hot spots for formation, Feltgen said, also will shift in coming weeks from tropical waves rolling off Africa to the Caribbean and Gulf of Mexico — locations where storms won’t be passing through Saharan dust as they approach Florida or elsewhere.
“The season is a long way from over,’’ he said. “It is a mistake to think the second half of the season will be like the first.’’