What States Will Sahara Dust Plume Hit and What Happens When It Does?

The vast Saharan dust plume that has been making headlines in the past few days is now brushing up against the southeastern U.S. coastline and is expected to move further inland over the coming days.

While trade winds regularly blow dust from the Sahara across the Atlantic Ocean at this time of year, the current event is extraordinary, both because of the geographic extent of the plume—which stretches nearly 5,000 miles from west Africa to the Gulf of Mexico—as well as its thickness.

After smothering much of the Caribbean, the leading edge of the plume will push into parts of the U.S. Gulf Coast—including Texas, Louisiana, Mississippi and Florida—over the course of Thursday, while also covering much of Central America and Mexico, according to NASA model projections.

"Currently, there are two concentrated areas of dust that have come off the Sahara desert and moved across the Atlantic. One is currently in the western portions of the Caribbean Sea and extends northward through the Yucatán Peninsula of Mexico and then across the central Gulf of Mexico, and it's starting to affect the Gulf Coast of the United States," Bob Oravec, a meteorologist with the National Weather Service in College Park, Maryland, told Newsweek.

In affected areas, visibility may be reduced, skies will take on a hazy, milky appearance, and sunrises and sunsets could appear more spectacular than usual, as the dust scatters light from the sun—where concentrations are low at least. However, higher concentrations can cause sunrises and sunset to appear more dull than usual. Furthermore, there will likely be widespread reductions in air quality—as has been experienced across many Caribbean islands.

In fact, air quality is already being affected in Florida, with Miami's health department urging people with respiratory problems to stay at home, AFP reported. Parts of Texas are also expected to experience unhealthy air quality on Thursday.

As Friday wears on, higher concentrations of the dust will move further northeastwards into the Gulf Coast states—and potentially further inland—producing more noticeable effects.

Massive Saharan dust plume now in the Caribbean Sea to complete a 5,000-mile journey from Africa to the U.S. this week: https://t.co/PQW8IyqAeQ pic.twitter.com/NvSQaXDbkk

— The Weather Channel (@weatherchannel) June 21, 2020

The plume will then spread out over most of the southeastern and mid-Atlantic states, and some parts of the Midwestern states, such as Illinois, over the weekend and early into next week, according to The Washington Post. However, thick parts of the plume may linger over parts of the South, including Alabama, Tennessee and Florida, on Saturday and Sunday, before dissipating.

Another significant concentration of dust at the trailing end of the plum, currently located midway between Africa and South America, could also reach the Gulf Coast at some point next week. However, it will likely not be as concentrated as the area of dust now affecting the Caribbean by the time it reaches this point.

"The second area of dust eventually moves back into the Caribbean Sea and the Gulf of Mexico towards the beginning of next week," Oravec said.

Saharan dust will likely lower the chances of rain in many areas. However, when rain does occur it could appear brown in isolated areas as storm clouds become mixed with the layer of dust.

Saharan dust, San Juan, Puerto Rico
A vast cloud of Sahara dust is blanketing the city of San Juan, Puerto Rico on June 22, 2020. RICARDO ARDUENGO/AFP via Getty Images

"The Saharan Dust is now getting entrained into the midlatitude system affecting the southeast U.S. and pulled north into coastal Louisiana and Mississippi. I wouldn't be surprised if the rain with the storms in the New Orleans area brings down a thin layer of dust to the surface," Dan Lindsey, a scientists with the National Oceanic and Atmospheric Administration's National Environmental Satellite, Data, and Information Service, wrote on Twitter.

In addition, the dust plume—which consists of warm, dry air—may also lead to reduced tropical activity in the Atlantic, suppressing the development of hurricanes and more minor storms.

The plume of dust originates in the Sahara where strong winds lift tiny particles of sand and minerals into a portion of the atmosphere known as the Saharan Air Layer (SAL)—a hot air mass that forms between late spring and early fall, extending from altitudes of around 5,000 to 20,000 feet.

From late June to mid-August every year, the SAL is blown westward across the Atlantic, often taking with it vast quantities of dust, as is occurring now. While much of the dust remains high in the atmosphere, some makes its way closer to the ground, where it can pose a health risk, particularly for those with respiratory issues, such as asthma and allergies, seniors and young children.

This article was updated to include comments from Bob Oravec. 5, 7, 12, 13