Where are all the big Atlantic storms? A year ago, Hurricane Harvey made landfall in Texas, kicking off a parade of destructive storms that made 2017 the costliest Atlantic season ever. So far in 2018, the region has been oddly still, with five named storms that failed to deliver any kind of impressive weather. At the moment there’s barely even a crack of thunder over the ocean, though forecasters are starting to watch a newly formed African wave.

The quiet conditions can be traced back to a ribbon of warm, dry air blowing off the Sahara Desert that has wrung moisture out of the atmosphere above the Atlantic. At the same time, hurricanes depend on warm water and large parts of the ocean have been unusually cool. The result has been day after day of clear skies and unimpressed meteorologists.

“It has been dead, dead, dead,” said Phil Klotzbach, lead author of the Colorado State University seasonal hurricane forecast. “We’ve had a lot of subtropical junk.”

This year’s named storms have been a quintet of misfits compared to the train of tropical power that caused more than $200 billion in damage across the U.S., Mexico and the Caribbean last year. Most of them have been relatively short lived and formed away from the heart of the tropics, including Hurricane Chris, which emerged near Bermuda in July, and then spun off into the North Atlantic. The lone hurricane spawned in the the main development region stretching from the Caribbean to Africa was Beryl, a tiny system that would have been hard pressed to cover Manhattan.

African Wave

An African wave that’s currently over the continent is expected to move into the Atlantic by Friday, with a 50 percent chance of becoming a tropical system in the next five days. While it’s still a long way from the Caribbean and the U.S., it could be a sign that storm season is about to pick up. September is typically the Atlantic’s most active month.

“I think we’re going to get some storms,” Klotzbach said by telephone. “Just because August has been super quiet, I don’t think September is going to be.” He expects to see 12 named storms before the season ends in November, a below-average year.

Another inhibiting factor this year has been shear, when winds at various altitudes blow at different strengths or directions. Hurricanes depend on structure and shear can rip them apart. Some models indicate the wind pattern may be waning, said Dan Kottlowski, a hurricane forecaster with AccuWeather Inc. in State College, Pennsylvania.

“Any feature that’s coming across right now has virtually no chance of developing,” he said. “If that shear breaks up, there will be more opportunity.”

September Storms

August isn’t always a good indicator of how September will unfold. In 1961, for example, no storms in August were followed by four major hurricanes in September with winds of 111 miles (179 kilometers) per hour or more.

Trillions of dollars in real estate stretch along the coastline from Texas to Maine, and Florida is the world’s second-largest producer of orange juice. Almost 20 percent of U.S. oil comes from the Gulf region. The hurricane-vulnerable coastline also accounts for 45 percent of U.S. oil refining capacity and more than half its natural-gas processing capacity.

Warm water in the Gulf of Mexico and along the U.S. East Coast is another source of concern, said Bob Henson, a meteorologist with Weather Underground.

Those pockets of warmth can lead to “hurricane turbo-charging,” he said. That’s what happened in 2005, when Hurricane Katrina got a boost on its way to wrecking New Orleans and killing about 1,800 people. “Climatologically the next six weeks are the peak.