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GRAPHIC: See how the dust affects the weather

Massive dust cloud over Atlantic inhibits tropical storms

The red oval and arrow indicate an area of dusty, warm, dry air over the eastern Atlantic that is making tropical storm formation less likely over the next few days.

NOAA

The red oval and arrow indicate an area of dusty, warm, dry air over the eastern Atlantic that is making tropical storm formation less likely over the next few days.

No tropical storms are likely to form in the southern Atlantic Ocean over the next few days.

For this, forecasters say, we can thank dust.

High winds have swept tiny sand and mineral particles from Africa into a huge dust cloud, about the size of the United States, pushing west across the ocean.

"It's just a huge area of dusty dry air, and it sits over the marine layer of the ocean," said Mike Clay, chief meteorologist at Bay News 9.

The dust and accompanying dry air tend to inhibit tropical storm formation, experts say.

Tropical storms need moisture and rising air to form. The dust cloud prevents air from rising.

It also can block sunlight, potentially lowering sea surface temperatures to levels less compatible with tropical weather. Tropical storms generally form in water that is 79 degrees or warmer.

None of this means hurricane season is over. In fact, after the dust ball, the season could still become active. And storms theoretically could still form in the Gulf of Mexico or Caribbean Sea, currently unaffected by the dust ball.

But dust already has had impact. The dry air from Africa helped dismantle Tropical Storm Dorian last week.

"Hurricanes don't like dry, and that's what killed Dorian," said George Sambataro, chief meteorologist at PC Weather Products.

Dorian sprang from the warm waters around Cape Verde off the west coast of Africa, a primary breeding ground for major storms.

But none are likely to develop there for as long as the latest dust cloud exists, Sambataro said.

It probably won't linger for much more than a week, said Chris Dolce, a meteorologist for the Weather Channel.

"It's usually a temporary thing," he said.

That means the tropics could regain moisture and return to normal by mid-August, just before hurricane season begins to peak, Clay said.

At the start of the season in June, meteorologists had predicted 2013 would be an especially active year for tropical storms.

Though the dust cloud could suppress tropical weather for the next couple of weeks, scientists said it won't necessarily have a long-term effect on the seasonal forecast.

And not everyone is convinced of its short-term significance.

"If there are fewer storms in the Atlantic in the next week or two, there probably would have been anyway," said Peter S. Ray, a professor of meteorology at Florida State University.

He said mineral dust has a slightly negative effect on tropical storm development. But some scientists believe dust clouds can actually contribute to development, enhancing the production of condensation and clouds in the atmosphere.

Will we see the dust in Florida?

Unlikely. It seldom gets this far west.

Dolce said the current cloud is predicted to pass above Puerto Rico today.

But it's so big, Clay said, it could touch the lower tip of the state.

"There would be red sunsets and sunrises,'' Clay said, "and there would be a kind of haziness in the sky."

Zachary T. Sampson can be reached at zsampson@tampabay.com or (727) 893-8804. Follow him on Twitter@zacksampson.

Massive dust cloud over Atlantic inhibits tropical storms 08/01/13 [Last modified: Friday, August 2, 2013 12:47am]
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