You are using an older browser version. Please use a supported version for the best MSN experience.

Hurricane-killing conditions over Atlantic have kept storms at bay. That's about to end

Sun Sentinel logoSun Sentinel 8/11/2020 By Amber Randall, Sun Sentinel

FORT LAUDERDALE, Fla. — Florida and the rest of the coastal U.S. have had a bubble of protection from hurricanes so far this year, but it’s about to burst as the Atlantic heads into what’s forecast to be a record-breaking season.

Dust carried across the ocean from Africa is disappearing, sea temperatures are creeping warmer, and storm-killing wind shears are going away — changes that are combining to clear the way for storms to form and grow stronger.

Two updated seasonal forecasts issued last week broke the bad news. The National Oceanic and Atmospheric Administration predicted as many as 25 storms — more than the agency has ever forecast — and Colorado State University forecast more storms than any season except 2005, the year of Hurricanes Wilma and Katrina.

“It’s the switch-point in the Atlantic, sea surface temperatures, also the winds are more favorable,” Dr. Jason Dunion, a scientist with the University of Miami and NOAA, said. “The conditions are really becoming ripe for more activity.”

The Saharan air layer forms every year over Africa starting in mid-June, carrying a plume of dust over the Atlantic that slows the development of storms. The winds, which are typically a mile or two above the surface, can reach speeds of 25 miles per hour, or even higher. Dunion said that’s enough to rip a storm apart.

That air layer is also dry, which starves storms of moisture they need to become hurricanes.

“In late June, it was some of the most active (Saharan air layers) we’ve seen on record,” Dunion said. “It was difficult for sure for tropical cyclones to really intensify because these outbreaks were so large and they were covering most of the Atlantic while they were coming across.”

This year, there was as much as 70% more dust in the atmosphere than usual, making it a record setter since experts began documenting the phenomenon, according to NOAA.

The extent of the dust’s impact on storms isn’t certain, but Dan Kuttowski, a forecaster with AccuWeather, said it’s possible this year’s record plume helped keep storms from growing into hurricanes.

“The fact that it was so active with the SAL early on, it’s hard to link that without any dust storms, what would the activity have looked like,” Dunion added. “We don’t have a great answer for that right now. It’s an ongoing question.”

By August, the Saharan dust dissipates — and that means growing season for storms.

“This is the reason why most, about 85%, of all development takes place in August in the next week or so. The dust and dry air isn’t as big of a problem,” Kottlowski explained.

At the same time, other environmental factors are coming together to cause the tropics to heat up.

“The tropical waves coming off the coast of Africa; they are taking advantage of very warm water or lower shear, so they are going to develop,” Kottlowski explained. “There is a better chance that they will be able to overcome the dry air and the dust that they don’t have the ability to earlier on in the season.”

That’s what is currently playing out in the Atlantic, where Tropical Depression Eleven formed Tuesday afternoon, the National Hurricane Center announced in a 5 p.m. advisory.

It’s currently forecasted to become a tropical storm by Wednesday night and could be near or north of the Leeward Islands by the weekend. There are no coastal warnings or watches in effect right now.

———

©2020 Sun Sentinel (Fort Lauderdale, Fla.)

Visit the Sun Sentinel (Fort Lauderdale, Fla.) at www.sun-sentinel.com

Distributed by Tribune Content Agency, LLC.

AdChoices
AdChoices

More From Sun Sentinel

image beaconimage beaconimage beacon