Saharan dust cloud reaches southern U.S.: Here's what it means

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(NEXSTAR) – A massive cloud of Sahara Desert dust particles is affecting air quality in the Gulf of Mexico and southern U.S. Monday after traveling thousands of miles over the Atlantic Ocean from Africa.

The phenomenon isn’t unusual for May, June and early July, when thick dust plumes often show up in satellite images as milky, atmospheric swathes.

The Saharan dust usually travels about a mile above the surface of the Atlantic in a 2 to 2.5-mile-thick layer of very dry, dusty air, according to Dr. Jason Dunion, a University of Miami Hurricane researcher.

While much of the dust usually remains well above the ground, some dense plumes may cause ground-level air quality issues and cause irritation, especially for those with pre-existing respiratory problems.

(Courtesy: WFLA)

In Central Texas, for example, the air quality is projected to drop down to the upper range of the “moderate” category from Monday through Friday. The dust may cause health concerns for a small number of unusually-sensitive people, Nexstar’s KXAN reports, and the elderly and very young are urged to limit their outdoor time.

While low concentrations of dust are already overhead, higher amounts will move in Wednesday night and peak by Thursday before quickly mixing out of the air just in time for the weekend.

(Courtesy: KXAN)

In New Orleans, where “feels like temperatures” are expected to reach between 105 and 110 degrees Monday, the air quality fell to levels deemed unhealthy for sensitive groups as the dust moves in.

In the tropics, the National Hurricane Center is keeping an eye on a disturbance in the Caribbean. The NHC gives the system a 30 percent chance of formation over the next 5 days as it slowly moves northwest toward the Yucatan Peninsula.

(Courtesy: WGNO)

Along with acting as a natural fertilizer for many plants and ocean ecosystems, Saharan dust can also limit tropical activity. The dust is very dry and tropical cyclones need moisture to begin to organize. If a storm has already formed, the dust can weaken the storm from the dry air and the strong winds embedded within the plume.

Depending on how dense the plume is, Saharan dust can also create eye-popping sunrises and sunsets, marked by deep red and orange hues. Under dense conditions, the sky may appear milky white during the day with the dust blocking light and causing muted sunsets in the evening.

Experts also monitor the growth of toxic algal blooms after a study partially funded by NASA found that the iron-rich dust can set the stage for so-called red tides. Researchers off the West Florida coast said they found a quantitative link between red tides and the Saharan dust.

Red tides have been responsible for killing large numbers of fish, shellfish, marine mammals, and birds. Humans exposed to the toxic algae have also suffered skin and respiratory problems.



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