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Fewer hurricanes in July? Here’s how Hurricane Beryl and dust could affect storms

A large and relatively thick Saharan dust plume has emerged over the tropical Atlantic. The dust can inhibit hurricane formation. (Courtesy Cooperative Institute for Meteorological Satellite Studies)
Cooperative Institute for Meteorological Satellite Studies
A large and relatively thick Saharan dust plume has emerged over the tropical Atlantic. The dust can inhibit hurricane formation. (Courtesy Cooperative Institute for Meteorological Satellite Studies)
ֱ reporter and editor Bill Kearney.
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Now that Hurricane Beryl has traveled across the Atlantic and broken numerous records, such as being the earliest Category 5 storm in recorded history, what’s next for hurricane development in the Atlantic?

The good news is that powerful hurricanes such as Beryl often consume heat energy, and can create upwellings of cool water. That cooler water then curbs storm formation.

But Beryl may not play out that way, said climate researcher Brian McNoldy with the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science.

McNoldy checked his data points and said that sea-surface temperatures had cooled slightly in the southern Caribbean, but that he had not seen any significant cooling in Beryl’s wake just yet.

“My hunch, because of where it tracked, and because it was moving quickly, I don’t think it will leave much of a cold wake,” he said.

McNoldy cited four factors that go into creating a nice, cold wake: Storms should be wide, slow moving, very intense, and travel over water where the surface is hot, but the deeper water is cold.

“Even though Beryl was certainly very strong, it wasn’t especially large, it was moving pretty quickly, and the warm water (in the Main Development Region for hurricanes) is really deep,” he said.

There may not be much of a cool wake, but there is an abundance of something else that could cripple storm formation — dry Saharan dust.

Dust blowing off the desert areas of North Africa and traveling over the tropical Atlantic, where hurricanes often form, is a pretty regular occurrence every June and July, said Cameron Pine, of the National Weather Service. “As the African Monsoon comes into full swing, we get these big plumes of dust that come off Africa and they can extend over a great swath of the Atlantic Ocean,” he said.

The plumes usually travel at an altitude of around 18,000 feet, and can hamper storm development.

“For tropical development, one of the main ingredients is ample moisture in the atmosphere. If you have an increase in the Saharan air layer, that creates dry conditions that are a negative for tropical development,” Pine said.

“Dust can put a brake on things for a while,” McNoldy said.

After checking the latest satellite imagery of the current dust plume, McNoldy said, “It’s really substantial out there now.”

He said, not only does the dry air curtail hurricane formation, but if it’s a fairly thick plume, it actually absorbs a decent fraction of the sun’s energy before that energy reaches the ocean and heats it. In other words, the dust, if thick enough, can help the oceans cool a bit, and make hurricanes in the remainder of July less likely.

“That’s fine by me,” said McNoldy.

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