LOS ANGELES -- Clear, blue skies are turning brown — again.
A historic Saharan dust plume blanketed the deep South last week, and another plume is now impacting the Gulf Coast.
This new dense air mass developed off Western Africa and traveled nearly 5,000 miles across the Atlantic Ocean. It reached the United States on Tuesday, bringing dust particles to the deep Southern United States.
The second round of dust lifted to the north into the Gulf of Mexico, according to NASA’s GEOS-5 model, and will continue to spread across the South.
A Saharan Air Layer (or SAL) is a mass of dry and dusty air, which forms over the Sahara Desert and moves over the North Atlantic.
Frank Marks, director of the Hurricane Resarch Divsion at NOAA's Atlantic Oceanagraphic and Meteorological Laboratory, said that the plumes are frequent in the summer, especially in June and July, and take about 10-12 days to cross the Atlantic."
The one we had was probably the most intense on record so far, and they've been keeping records of these dust outbreaks probably about 70 years," Marks said of last week's dust plume.
Several numerical models predict that the second plume’s track will head toward the plains states, before turning eastward to impact the Southeast and Mid-Atlantic.
Marks said the most recent round of dust looked more diffused on satellite, so it is likely be less concentrated. “It’s intense, but I wouldn’t say it’s intense as the one that just came by,” Marks said.
The second plume also may cause deterioration in air quality across the United States.
According to the environmental consulting firm Sonoma Technology, “A moderate-density plume of Saharan dust is currently impacting states in the Gulf region, leading to elevated particle levels, especially in Texas and Louisiana.”
Sonoma Technology added, “Light southerly winds will continue to transport dust into these regions today and tomorrow. As a result, Air Quality Index, or AQI, levels are expected to be Moderate today and tomorrow throughout Louisiana, much of east Texas, and parts of Oklahoma, Arkansas, Mississippi, Alabama, and Florida.”
The air quality firm said the plume isn’t as dense as the dust plume that impacted the eastern U.S last weekend, but air quality levels will likely remain in the moderate range throughout the region into the weekend. “Dust could make it as far inland as Kansas, Missouri, Iowa, and Illinois,” Sonoma Technology wrote.
While the sky will appear hazy, the second Saharan dust plume has the potential to produce colorful sunsets in the South.
According to NOAA, the dry layer of air usually travels about one mile above the ocean surface, and can inhibit tropical cyclones and activity.Leftover air from last week’s Saharan dust plume has helped suppress thunderstorm development in Florida, causing temperatures to climb in the state.
On June 24, the first dense Saharan mass reached the Caribbean. NOAA shared a satellite image of the dust plume. “This particular plume has reportedly spread over the Caribbean, reducing visibility in some areas to five miles.”
Meteorologist Jeff Beamish wrote, “The Saharan air layer’s definitely not a new phenomenon. It happens yearly, with varying amounts of dust traversing the Atlantic basin.”