Dust from the Sahara Desert has surged into the Caribbean and may funnel its way toward the Gulf Coast of the United States this weekend, keeping the tropics at bay for the near future.
Known as the Saharan Air Layer (SAL), this dry dust plume commonly forms from late spring through early fall, moving out into the tropical Atlantic Ocean about every three to five days, according to NOAA’s Hurricane Research Division (HRD).
The HRD says the SAL 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.
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. NASA says the dust can also lead to the creation of toxic algal blooms in the Gulf of Mexico.
The dust also reaches South America at times. In fact, a study by NASA scientists found that the dust acts as a fertilizer for the Amazon rainforest.
This current plume of Saharan dust departed Africa on Father’s Day and quickly moved westward into the tropical Atlantic. It appeared on GOES-16 satellite imagery Thursday afternoon off the coast of northern South America.
Dr. Jason Dunion of the HRD told weather.com in an email that the SAL should mostly stay south of Florida due to a high-pressure system in the subtropical Atlantic shoving it southward. However, the Florida Keys could get “nicked” by it, he said.
Dunion added that the dust plume should reach the southern Gulf of Mexico late Saturday, then the Gulf Coast states – including Texas, Louisiana and Mississippi – by late Sunday.
The forecast animation below shows a general idea of where the dust is headed in 12-hour increments from Friday morning through Saturday morning.
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.
“I expect a fairly active stretch of SAL outbreaks in the Atlantic over the coming weeks,” Dunion said. “The next strong SAL outbreak is forecast to move off the Africa coast early next week.”
This is overall good news, as it will likely inhibit tropical storm and hurricane development in the Atlantic Basin for at least the next week or two.
The Mazatlan Post