LANSING, Mich. (WZMQ) – Unseasonably warm temperatures across Michigan led to rapid snowmelt this weekend, but state officials say the primary cause of recent air quality alerts in southern Michigan was a weather phenomenon known as an atmospheric inversion.
Alec Kownacki, a meteorologist with the Air Quality Division at the Michigan Department of Environment, Great Lakes, and Energy, said melting snow was not the main driver of the pollution spike.
He explained that while snowmelt can increase the evaporation of pollutants into the air as they attach to water droplets, the more significant factor was warm air sitting above a colder surface layer.
“When you have warm air above cold air, that creates a very stable atmosphere, and that causes air to not really move around or mix,” Kownacki said.
With light winds and sunny skies, emissions from vehicles, industry, and other routine sources accumulated over several days instead of dispersing.
“Those emissions were staying in the atmosphere, not mixing or moving around. So it was just kind of the accumulation of those pollutants over multiple days,” he said.
Sunday marked the peak of the event, with elevated levels of fine pollution, known as PM 2.5, in areas including Lansing and parts of southern Michigan.
Although winter air quality alerts may seem unusual, Kownacki said this type of setup typically occurs at least once each year, often during late winter or early spring thaws.
“This actually happens pretty regularly each year, believe it or not,” he said.
What made this weekend different was the combination of multiple days of unusually warm temperatures over a dense snow pack, creating near-ideal conditions for pollution to build up.
By Monday, increasing wind speeds broke down the inversion layer.
“The wind picked up, and that just kind of blows all the pollutants out of here,” Kownacki said.
Air quality conditions have since improved across the affected regions.
