Air quality alert for all of Minnesota Thursday and Friday

Another major Canadian wildfire smoke plume is blowing into Minnesota.

The Minnesota Pollution Control Agency has issued another air quality alert for all of Minnesota. The alert runs from midnight Thursday (Wednesday night) until 11 p.m. Friday.

The alert is driven by another thick plume of Canadian wildfire smoke pushing southward into Minnesota from southern Canada. NOAA’s RAP model shows the thickest plume of smoke across central and eastern Minnesota. Here’s the forecast image for 7 p.m. Thursday.

The MPCA forecast discussion indicates this could be the worst smoke event for some areas of Minnesota since 2021.

This afternoon severe weather will be possible along a cold front. Following this front will be another smoke incursion. This incursion will have a source region near Lake Winnipeg - which has been sitting in an AQI above 300 for the day.

The AQI totals will decrease some as the air moves along the front - but this source region highlights the fact that this next smoke incursion may be impactful enough that the general public will be impacted. For now will keep the air quality alert posted through this morning and will make a call on a new alert when it expires to limit confusion.

Of note - the smoke models have so far been underplaying the smoke concentration observed in Canada. Because of that there is some uncertainty on how high concentrations may be in MN. For now made the forecast Thursday easy with Red (Unhealthy for All) in the forecast across the northern half of MN with Orange (Unhealthy for Sensitive Groups) across the rest of MN excluding the southwest corner.

Smoke will impact all but the very southwestern part of MN so the forecast there remains in Yellow (Moderate). This was done to indicate the possibility of significant smoke concentrations - ones that may rival what was observed in July/August 2021 here in Minnesota. This situation will continue to be very closely monitored.

Here are the alert details from MPCA.

Air quality is expected to reach the red AQI category in northeast and east central Minn., which is unhealthy for everyone.

The Minnesota Pollution Control Agency (MPCA) has issued an air quality alert for all of Minn. The alert takes effect at midnight on Thursday, Aug. 17, and runs until 11 p.m. on Friday, Aug. 18.

The affected area includes the Twin Cities metro, Brainerd, Alexandria, Albert Lea, Marshall, Worthington, Rochester, Hinckley, St. Cloud, Winona, Ortonville, Mankato, Bemidji, East Grand Forks, Moorhead, International Falls, Two Harbors, Hibbing, Ely, Duluth, Roseau, and the tribal nations of Upper Sioux, Mille Lacs, Prairie Island, Leech Lake, Red Lake, Grand Portage, and Fond du Lac.

Heavy ground-level smoke from wildfires in the Northwest Territories of Canada is moving south across central Canada and towards Minn. on Wednesday. A strong cold front will bring this smoke across the entire state on Thursday. Smoke will reach the border around midnight on Thursday, the Twin Cities around noon, and southern Minn. by 3 p.m. This smoke will be heavy and air quality may reach the Red (Unhealthy) AQI category for much of eastern Minn. Smoke will linger across the eastern half of the state on Friday and fine particle levels will continue to be high for most of the day. Winds will become southerly Friday afternoon and smoke will begin to retreat away from Minn. and disperse. Air quality should improve below alert levels by late Friday.

Fine particle levels are expected to reach the red air quality index (AQI) category, a level considered unhealthy for everyone, across northeast and east central Minn. This area includes the Twin Cities metro, Brainerd, Hinckley, St. Cloud, Bemidji, International Falls, Two Harbors, Hibbing, Ely, Duluth, Roseau, and the tribal nations of Mille Lacs, Prairie Island, Leech Lake, Red Lake, Grand Portage, and Fond du Lac. In the red area, sensitive groups should avoid prolonged or heavy exertion and limit time spent outdoors. Everyone should limit prolonged or heavy exertion and time spent outdoors.

Fine particle levels are expected to reach the orange air quality index (AQI) category, a level considered unhealthy for sensitive groups, across western and southern Minn.. This area includes Alexandria, Albert Lea, Marshall, Worthington, Rochester, Winona, Ortonville, Mankato, East Grand Forks, Moorhead, and the tribal nation of Upper Sioux. In the orange area, sensitive groups should limit prolonged or heavy exertion and time spent outdoors.