


An avalanche of fine particles rolled across northwest Indiana and north-central Illinois on Friday, turning day to night in an area of the country rarely hit by dust storms.
A dark cloud suddenly brought near-zero visibility conditions on Friday afternoon to major highways, including Interstates 55 and 57 in Illinois, leading the National Weather Service to fire off a series of warnings about “dangerous, life-threatening” conditions on roads.
As the wave of sifting dust blew into Chicago, it created a dramatic scene. Visibility dropped to a quarter-mile at Chicago Midway International Airport.
“This is not common at all,” Zachary Wack, a meteorologist with the Weather Service office in Romeoville, 30 miles southwest of Chicago, said on Friday.
Friday was the first time that the Weather Service office in Romeoville, which covers a large area that includes Chicago, had ever issued a dust storm warning for the city.
Mr. Wack was working as the first warnings were being issued. Then the dust storm arrived at his office.