Sahara Dust Storm Hits Jamaica and Puerto Rico on Way to U.S.

A vast plume of Saharan dust has shrouded large parts of the Caribbean, and is expected to reach the southeastern U.S. later this week.

Several Caribbean islands reported hazardous air quality as residents took to social media to post images of hazy skies and vehicles covered in dust.

While Saharan dust clouds are not uncommon in the Caribbean at this time of year, experts say that a plume of this size and concentration has not been seen for around half a century.

"This is the most significant event in the past 50 years," Pablo Méndez Lázaro, an environmental health specialist at the University of Puerto Rico, told the Associated Press. "Conditions are dangerous in many Caribbean islands."

The first concentration of the dust plume, which extends thousands of miles across the Atlantic from west Africa to the Caribbean, reached Puerto Rico and the Virgin Islands on Monday, causing hazy skies and poor visibility.

In San Juan, Puerto Rico, visibility was limited to around 5 miles, around half the figure seen during previous Saharan dust plumes, Gabriel Lorejo, a meteorologist with the National Weather Service in San Juan, told The Washington Post.

Sahara Dust before and after,this is PR right now,the worst dust ever. pic.twitter.com/lLxMv8mo6h

— T C Cape (@tmcsjgw18) June 21, 2020

"We have many models that indicate the highest dust concentration is from around 5,000 feet all the way down to the surface. It's pretty extreme," Lorejo told the Post.

In fact, concentrations of the dust were so high in Puerto Rico, that the aerosol optical thickness—a measure commonly used to estimate the quantity of particles in the atmosphere—reached around 2 on Monday, a level not seen since records began 15 years ago, Olga Mayo, an atmospheric chemist at the University of Puerto Rico, told the Post.

Poor air quality and hazy skies were also reported in Jamaica, where the Blue Mountains—usually clearly visible from the capital Kingston—were hidden by the thick concentrations of dust.

A thin layer of #Saharandust is in the surface of our cars, exterior tables, fans, etc. This extraordinary dense SAL was lifted from the Saharan desert and traveled to the Caribbean. The red color comes from the iron minerals that travel in this layer. pic.twitter.com/DRLP13kXRp

— Ada Monzón (@adamonzon) June 23, 2020

"It's the worst I've seen since we've kept records," Evan Thompson, director of the meteorological service division in Jamaica, told Reuters.

The plume of dust originates in the Sahara where strong winds lift tiny particles of sand and minerals into a hot air mass known as the Saharan Air Layer (SAL), which forms over the desert from late spring to early fall.

Extending between altitudes of 5,000 and 20,000 feet, the SAL is blown westward across the Atlantic every few days by trade winds, often transporting vast quantities of dust. Usually the transport of dust peaks between late June and mid-August, according to the U.S. National Oceanic and Atmospheric Administration.

Saharan dust, San Juan, Puerto Rico
A woman meditates as 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 dust plume affecting the Caribbean is expected to reach parts of the southeastern United States, from Texas to Louisiana by late Friday or early Saturday, although concentrations are likely to be lower than those seen in Puerto Rico as the dust spreads out.

Nevertheless, AccuWeather Senior Meteorologist Dan Kottlowski said that people with respiratory issues should not spend long outdoors in areas affected by the dust, due to the fact that the tiny particles can exacerbate these issues.