Skies over the Great Lakes and Midwest have been filled with smoke from numerous wildfires in Canada, some burning out of control. Most of the smoke in the Stateline has remained in the upper levels of the atmosphere. But as a cold front passes through the region late Thursday night, the smoke aloft could be pushed closer to the surface early Friday morning.

An ‘Air Quality Alert’ has been issued for not only southern Wisconsin, but the entire state as air quality is expected to deteriorate as the cold front moves through. Cold air is more dense than warm air, causing it to sink down closer to the surface. As this happens, the smoke that has been mostly aloft the last few days will also sink towards the surface. This could give our skies an even hazier look during the day Friday. It’s also possible for there to be a little more of a smoke smell Friday. How much, or how little, we actually end up seeing – or smelling – is yet to be determined, but particulate matter concentrations are forecast to increase before cleaner air moves in late Friday. According to the Wisconsin Department of Natural Resources, the air quality index is expected to reach the ‘unhealthy for sensitive groups’ level later tonight and Friday.

The smoke may linger in the atmosphere, likely back in the upper levels, through the weekend and next week as our jet stream pattern remains from the northwest. This would cause the hazy/milky sky to continue into next week.