A layer of airborne dust from the Saharan Desert has arrived in San Antonio, with forecasters calling for it to remain in the region over the weekend.

“It’s pretty much here,” said National Weather Service meteorologist Aaron Treadway, who noticed the hazy views on his drive to the service’s New Braunfels office for work Friday afternoon.

Saharan dust is no stranger to Texas skies during the summer months, when prevailing westerly winds blow it across the Atlantic and toward the Gulf of Mexico. But this year, scientists are calling the plume unusually large and thick.

“While Saharan dust transport across the ocean to the Americas is not uncommon, the size and strength of this particular event is quite unusual,” NASA atmospheric scientist Colin Seftor said in a Friday blog post from the space agency. “Also, if you look off the coast of Africa you can see yet another large cloud coming off the continent, continuing to feed the long chain of dust traveling across the Atlantic.”

This image is a composite of the OMPS aerosol index and the VIIRS visible image both from NASA/NOAA’s Suomi NPP satellite on June 24. The image shows the dust plume moved over the Yucatan Peninsula and up through the Gulf of Mexico. Credit: NASA/NOAA, Colin Seftor

Texas forecasters expect San Antonio to be at its dustiest on Saturday, when officials with the Texas Commission on Environmental Quality (TCEQ) expect the city to experience concentrations considered unhealthy for sensitive groups, such as those with asthma or other chronic lung conditions.

“Heavy amounts of African dust will arrive along the coast and begin moving inland over the course of the day,” TCEQ air quality forecasters wrote in their daily update Friday morning.

Whether fine particles in the air reach unhealthy levels depends on the dust’s concentration and where it falls in Texas, along with the presence of rain, the TCEQ forecasts states.

Much of the South Texas region saw showers Friday, with San Antonio expected to have received half an inch to an inch of rain by the end of the day.

“I would hazard a guess that if someone does see one of these showers for the next hour or two, when their car dries, it’s going to be a little bit more dusty,” Treadway said Friday. “It’s going to be able to pull some of that dust particulate out of the atmosphere in that shower and be left over on someone’s car.”

The air ferrying the dust along is steadily drying out moisture that’s been hanging over the region during the last few days, Treadway said.

Hazy skies should begin clearing by Sunday and into early next week, according to the TCEQ, as the dry, dusty air moves northward starting Sunday.

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Brendan Gibbons

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.