November 28, 2020

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Saharan Dust Forecast to Surge Into the Southern U.S. Next Week

  • An expansive plume of dust from the Sahara Desert has surged into the tropical Atlantic Ocean.
  • It has already reached the Caribbean Sea.
  • Some of the dust could reach the Gulf of Mexico and the United States next week.
  • This Saharan air layer generally hampers tropical cyclone development.

An outbreak of dust from the Sahara Desert has already reached the Caribbean Sea, and it’s expected to reach the Gulf of Mexico and parts of the United States next week.

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).

You can see in this animation from Tuesday how an expansive area of dust has moved from Africa to the central and eastern tropical Atlantic Ocean.

Saharan dust tracks as far west as the Caribbean Sea, Florida, and the Gulf of Mexico each year – a 5,000-mile-long journey. The dust particles can contribute to hazy skies at times during the summer in the Caribbean Islands, South Florida, the Florida Keys, and the U.S. Gulf Coast.

The dust can also cause toxic algal blooms in the Gulf of Mexico, according to NASA. It can also aggravate those suffering from respiratory issues such as asthma and COPD.

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 National Weather Service in Puerto Rico noted on Monday that a weak Saharan Air Layer was creating hazy skies and providing dry air to their area early in the week.

This weekend, a more concentrated area of dust is expected to spread into the Caribbean. You can see this in the forecast below from NASA’s GEOS-5 model, which shows an expansive area of dust moving westward.

At least some airborne dust is then expected to first reach the Gulf of Mexico and parts of the United States by early next week, followed by what could be a more potent push of dust later in the week.

The National Weather Service in Houston mentioned that their area could see red skies at sunrise and sunset next week because of the dust. This could also happen on other parts of the U.S. Gulf Coast, depending on the exact path of the dust and how much of it spread that far west.

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 on 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 the 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.

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