Once or twice a week in late spring and summer, gusts of wind send dust from the Sahara Desert flying across the Atlantic Ocean, in what's known as the Saharan Air Layer. But a particularly concentrated dust cloud is currently midair, en route to land in Central and South America, potentially settling on urban cities like Caracas, Bogota, Panama City, Port-au-Prince, and San Juan this weekend, the Atlantic Cities reports. The National Oceanic and Atmospheric Administration has released a visualization of how the dust is expected to travel, and you can also follow it in real time. (More Sahara stories.)