Cold front will drive Canadian wildfire smoke to ground level Thursday

Wildfire smoke is driving another air quality alert in Minnesota.

The smoke plume from Canadian wildfires is widespread across Minnesota and the Upper Midwest this week. A cold front pushing through Thursday will cause sinking air that will bring some of that elevated smoke down to ground level.

Below is the National Oceanic and Atmospheric Administration’s Rapid Refresh model near-surface smoke loop through Thursday. You can see the smoke front sweeping across Minnesota Thursday.

The Minnesota Pollution Control Agency has issued another air quality alert for Thursday that includes much of northern Minnesota.

Air quality is expected to reach the red AQI category in northwest Minnesota, which is unhealthy for everyone.

The Minnesota Pollution Control Agency (MPCA) has issued an air quality alert for northern Minnesota. The alert takes effect Wednesday, May 17, beginning at 10 p.m. and runs until Thursday, May 18, at 12 p.m. The affected area includes northwest and north central Minnesota, and the tribal nations of Leech Lake, Red Lake, and Mille Lacs.

A band of very heavy ground-level smoke from wildfires in northern Alberta and Saskatchewan is currently moving southeast and stretches from southern Manitoba to eastern Montana. A strong cold front will pull this smoke south towards northwest Minnesota. Smoke will reach northwest Minnesota around 10 p.m. tonight (Wednesday). Northwest winds will push the smoke through the state and the smoke should reach central and southwest Minnesota by 12 p.m. on Thursday. Smoke will likely move through the Twin Cities and southeast Minnesota beginning in the late afternoon on Thursday. Smoke will begin to clear and air quality should improve across northwest Minnesota beginning Thursday afternoon. Smoke should clear southeast Minnesota by Friday morning. If smoke creates air quality impacts in other parts of the state, we will issue an alert.  

Fine particle levels are expected to reach the red air quality index (AQI) category, a level considered unhealthy for everyone, across northwest Minnesota. This area includes Moorhead, East Grand Forks, Roseau, and the Red Lake tribal nation. In the red area, everyone should avoid prolonged time outdoors. Fine particle levels are expected to reach the orange AQI category, a level considered unhealthy for sensitive groups, across north central Minnesota. This area includes Ely, International Falls, Brainerd, and the tribal nations of Leech Lake and Mille Lacs. In the orange area, sensitive groups should avoid prolonged time outdoors.

Here’s the forecast discussion from the MPCA.

Winds will be southerly today and elevated smoke present over the state is expected to linger over the western half of the state. Some smoke may mix to the surface, and fine particle levels may reach the Yellow (moderate) category for western Minnesota today. Air quality should improve for the rest of the state and should be in the Green (good) category. A strong cold front will move into northwest Minnesota early tomorrow morning and another wave of smoke is expected to move in behind the front. It's likely ground-level smoke will be heavier with this wave than yesterday's. Fine particle levels may reach the Orange (Unhealthy for Sensitive Groups) across western MN. Another Air Quality Alert may be needed for tomorrow. This wave of smoke should be brief and air quality should improve back into the Green category statewide on Friday, as high pressure moves into the state.

Thursday’s air quality forecast across Minnesota highlights reduced air quality in the western half of the state.

The cold front should scour out most of the smoke in Minnesota by Friday. Expect air quality to improve Friday.