It’s nice to see the color blue in the Weather Lab sky again this morning after a smoky red sunset last night.
Minnesota’s air quality index (AQI) improved dramatically today as a more northerly wind flow shoved Monday’s thick smoke plume southward.
The massive plume from fires in Alaska and western Canada will still be swirling around the northern tier this week. Expect smoke of varying thickness as winds shift back into the northwest around 10,000 feet.
Right now, I don’t see a repeat of Monday’s incredible AQI reading of 187, but air quality may vary across Minnesota over the next few days.
Here’s a look at today’s improved AQI numbers and forecast from the MPCA.
Anatomy of a ‘smoke spike’
How do we go from heavy cleansing rain to thick smoke in a couple of hours? It was the perfect storm to drive the elevated thick smoke plume down to ground level Monday afternoon. You could smell smoke in the air.
As we’ve reported in this space for over a week, thick smoke plumes have been wafting southeast from a record number of wildfires in western Canada and Alaska.
Here’s the map with currently burning large wildfires in Canada.
After yesterday’s rain front, a strong zone of subsidence (sinking air) behind the front drove the elevated smoke plume down to ground level. The result was a dramatic increase in smoke at ground level and a spike in AQI readings.
I pulled some hourly observations from Minneapolis-St. Paul International Airport Monday that help tell the story. As the smoke reaches sensors at ground level, visibility drops as low as 2.5 miles, and smoke is reported for several hours on the hourly observations between noon and 8 p.m. The freshening north breeze finally blows the plume southward last night.
Forecast: Dry now, steamy weekend
Our latest Canadian air mass brings another round of free air conditioning this week. Temperatures in the 70s today rise to near 80 degrees tomorrow. Late this week winds turn into the southwest. An increasingly muggy and heated air mass arrives by the weekend, and tropical dew points near the 70 degree mark arrive by Sunday.
One product that often does well with developing heat spikes is the Global Forecast System Long-Range Model Output Statistics Forecast from the National Oceanic and Atmospheric Administration.
The outlook into the upcoming weekend suggests temps pushing the 90-degree mark by Sunday.
For the record, I think the 16-day GFS output below is probably too extreme. It is even more aggressive with the potential weekend heat spike, cranking out 103 degrees on Sunday afternoon in the metro. It does lend more confidence to the notion of two to three days in the 90s though.
Stay tuned and keep the AC handy.