It has been an incredible wildfire season across the western United States, and North Dakota is feeling the effects of all the smoke, especially the past couple of days.
Yesterday’s air quality was unhealthy for everyone and today it dropped down to the moderate level.
Why was yesterday’s smoke was one of the worst yet?
Patrick Ayd, National Weather Service, “There was a really dry warm air mass that was over us on Tuesday, and that was upstream from those fires in previous days and that really helped to liven up the fires.”
This helped to produce a lot of smoke that all got transported across North Dakota with winds from the west.
The smoke was also trapped behind cooler air.
“When that cold front finally made its way through Northwest North Dakota especially during the early afternoon on Tuesday then all of the sudden the visibility in Williston really dropped down,” says Ayd.
As the cold front continued south and east it became really smoky Tuesday night and the air on Wednesday was stagnant… Oddly, there was no wind.
Ayd says, “We didn’t have any air mass exchange or change of winds so there was nothing to get rid of all the smoke that was already trapped.”
There are a number of different weather conditions that can affect where the smoke ends up at, changing the air quality.
Chuck Hyatt, Air Quality Division of the Dept of Health, says, “Temperatures, wind direction, wind speed, even the extent of the fire itself, how hot it is determines how high that smoke ultimately raises.”
Air quality was at unhealthy levels on Wednesday and now that the wind direction changed, conditions are much better.
Ayd adds, “Then through the day we’re also getting some northerly winds, which will help to clear out some of low levels of the atmosphere.”
Scattered rain showers also helped clear out the the smoke from the skies.
Now, northerly winds are coming from an area of Canada that is not impacted by the fires.
The smoke was so thick that automated sensors used to calculate cloud heights were way off.
Clouds that were really at 25-thousand feet– sensors showed them at 3-thousand feet.