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Even as plumes of heavy smoke from Alberta and Saskatchewan wildfires force thousands from their homes, officials find a silver lining, as the smoke is actually keeping the fires more under control.

Read how thick smoke helps, not hurts, the wildfire fight


Scott Sutherland
Meteorologist/Science Writer

Thursday, July 2, 2015, 5:14 PM - Even as plumes of heavy smoke from Alberta and Saskatchewan wildfires force thousands from their homes, officials find a silver lining, as the smoke is actually keeping the fires more under control.

Evacuation centres in central and southern Saskatchewan are reportedly housing at least 5,000 people as of Thursday, all displaced from their homes by thick smoke drifting down from wildfires burning in northern parts of the province. The evacuations were prompted by the significant health risk this smoke represents, and Environment Canada has issued special air quality statements for northeastern Alberta, all of Saskatchewan and all but the northeastern regions of Manitoba in response.

Despite this health risk, though, the thick smoke is actually having a beneficial impact on the very fires that are producing it in the first place.

"As much as it's not good for people, because the cloud layer filled with smoke and is so thick, our temperatures are roughly 10 degrees cooler and our humidity is 10 to 15 per cent higher," said Steve Roberts, Executive Director of Saskatchewan's Wildfire Management Branch, according to the Canadian Press. "That combination means the fire activity drops significantly."

"It's helped us secure, especially, those fires that are close to communities by putting people on the ground and getting some hose lines in place."

Most, if not all, of these wildfires were sparked by lightning strikes from the scattered thunderstorms tracking through northern regions of the Prairie provinces and in the Northwest Territories. With abundant snowfall in the winter to provide those regions with moisture through spring and summer, storms wouldn't be much of a problem. However, with the dry winter and early spring this year, conditions are very dry. Under clear skies, the Sun heats the ground, which radiates that heat into the air, and a good portion of the scant moisture in the soil evaporates into the air as well. As the air continues to warm, it draws in more moisture until the soil is dried out, but as the temperature of the air continues to rise after that, the humidity of the air drops. Thus, with low soil moisture and low humidity during the day, the trees become like dry kindling, ready to burst into flames with the first lightning strike or glowing ember blown in by the wind. This has been the situation so far, making it very difficult to contain the wildfires currently raging in the north, and with more fires popping up on a nearly daily basis.

With the thick smoke layer from the fires currently blotting out most of the sunlight, it is basically acting as a self-limiting factor. With less sunlight reaching the ground, less heat is being radiated into the air, keeping the air cooler. This results in less evaporation of soil moisture, and the water that does evaporate into the cooler air simply raises the humidity level. Higher humidity not only keeps the potential for new fires down, but it also helps to keep current fires more under control.


RELATED: Smoke from distant fires intensified devastating 2011 tornado outbreak, says study


Fire Status

As of Thursday, July 2, over 430 fires are currently burning in Alberta, Saskatchewan, Manitoba and the Northwest Territories:

  • 119 wildfires fires reported in Alberta, just under one-half of which are currently under control,
  • 116 active fires burning in Saskatchewan, 51 of which cover area greater than 100 hectares each, and only six currently labelled as contained,
  • 63 active fires Manitoba, with more being sparked by lightning from thunderstorms passing through the province today, and
  • 139 fires in the Northwest Territories, with 44 being fought and only 11 of those currently under control.


Satellite view of the wildfires (marked in red) and the resulting thick smoke. Credit: NASA Earth Observatory


A close-up view of the highlighted area in the image above. Credit: NASA Earth Observatory

Sources: The Weather Network |  Chronicle Journal |  Canadian Press | Environment Canada | Saskatchewan Wildfire Management | Government of Manitoba | Alberta Wildfire Info | NWT Fire | NASA

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