At a Glance
- An expansive plume of dust from the Sahara Desert has moved from Africa to the southern United States.
- The dust traveled 5,000 miles across the Atlantic, Caribbean and Gulf of Mexico.
- The dust is creating less healthy air quality.
- There could also be brilliant sunrises and sunsets.
- The dust was the thickest to move over the Puerto Rico area in years.
A massive plume of dust from Africa's Sahara Desert has spread into parts of the U.S. after traveling 5,000 miles across the Atlantic, Caribbean and Gulf of Mexico.
Known as the Saharan Air Layer (SAL), this dry dust plume commonly forms from late spring through early fall and moves into the tropical Atlantic Ocean every three to five days, according to NOAA's Hurricane Research Division (HRD).
The HRD says the Saharan Air Layer is typically located between 5,000 and 20,000 feet above the Earth's surface. It is transported westward by bursts of strong winds and tropical waves located in the central and western Atlantic Ocean at altitudes between 6,500 and 14,500 feet.
The densest plume of dust began to emerge off western Africa more than a week ago and has now moved into the South. You can see the general area where the dust is located right now in the analysis below from NASA's GEOS-5 model.
The dust has contributed to poor air quality in some areas since late this past week. Air quality alerts have been issued in portions of the Southeast and Ohio Valley, where air could be dangerous for some people.
There could also be brilliant sunrises and sunsets because of the dust in some areas.
Saharan dust tracks as far west as the Caribbean Sea, Florida and the Gulf of Mexico each year.
This particular dust event is unique because of its thickness over parts of the Caribbean Sea earlier last week. It had the highest concentrations of dust particles observed over Puerto Rico in at least the last 15 years, according to Dr. Olga Mayol of the Institute for Tropical Ecosystem Studies at the University of Puerto Rico.
Another plume of dust is tracking across the Caribbean this weekend. Some of that dust might reach the western U.S. Gulf Coast next week.
What the Saharan Air Layer Means for Hurricane Season
Given the SAL is most common during hurricane season, research has been done on how it can affect the development of tropical storms and hurricanes. According to NOAA, some of the potential impacts to tropical development caused by the SAL include:
- The dry air can create downdrafts (sinking air) around tropical storms and hurricanes, which may result in the weakening of tropical cyclones.
- Strong winds associated with the SAL can contribute to increased vertical wind shear – the change in wind speed with height – which makes the environment hostile for tropical cyclone development.
- The role dust plays in tropical storm and hurricane intensity is not known. However, some research says it might impact cloud formation.
The early part of hurricane season is typically quiet in the tropical Atlantic. But this outbreak of dust along with unfavorable upper-level winds will likely put a lid on any significant tropical development in the near-term future.
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.
