Huge Saharan Dust Plume Is Headed for the United States

Residents of the Southeast and Gulf regions can expect it to arrive this week.

Saharan dust plume
Saharan dust plume, seen by the NOAA-20 satellite on June 17, 2020.

 NOAA Environmental Visualization Laboratory / NOAA

We might not be able to travel to the Sahara Desert right now, but apparently the Sahara can come to us. This week, a massive plume of desert sand is expected to descend upon the southeastern United States. It has already travelled 5,000 miles across the Atlantic Ocean and reached the Caribbean Sea, and is now moving into the Gulf of Mexico. Residents of the Deep South can expect to see hazier air and other impacts of the dust plume by mid-week.

These dust plumes are not unusual. Officially known as the Saharan Air Layer (SAL), they typically form between late spring and early fall and are transported westward by strong trade winds. What makes this particular plume newsworthy is its size, described by the Washington Post as an "unusually thick cloud of dust," and the fact that it will track all the way into the United States.

There are pros and cons to the plume's imminent arrival in the U.S. It's likely to cause some spectacular sunsets and sunrises. As CNN explains, "Those tiny dust particles lofted tens of thousands of feet in the air do a great job of scattering the sun's rays at dusk and dawn, too, which gives way to stunning sunrises and sunsets. So, grab those cameras!" 

The plume also suppresses hurricanes, due to its surge of dry air. Hurricanes prefer humidity, which means that there will be less tropical activity for several weeks, until the plume dissipates – but don't expect that effect to last past July. Some meteorologists suspect that the dust might impede cloud formation as well. 

On the downside, not all the dust stays high up in the atmosphere; some falls closer to the Earth's surface, diminishing air quality, reducing visibility, and making respiratory issues like asthma and COPD worse.

An interesting fact about these Saharan dust plumes is that they enrich the Atlantic Ocean with nutrients, delivering phosphorous and iron to regions of the ocean that would otherwise be desolate. This allows cyanobacteria, an ancient form of phytoplankton, to grow. From a study published in Nature GeoScience,

"Saharan dust storms are largely responsible for the significant difference between the numbers of cyanobacteria in the North and South Atlantic. The dust fertilizes the North Atlantic and allows phytoplankton to use organic phosphorus, but it doesn’t reach the southern regions and so without enough iron, phytoplankton are unable to use the organic material and don’t grow as successfully."

Not all bacterial growth is good, however. Meteorologist Matthew Cappucci writes in the Washington Post that the Saharan dust can cause a species of bacteria called vibrio to proliferate: "Vibrio are problematic if ingested, primarily associated with undercooked seafood." 

If you live in the Caribbean or Southeast and Gulf regions of the U.S., take a moment to notice the skies in the coming days and to marvel at how interconnected our planet is.