Hot weather and dry conditions are common in any wildfire season, butterrain and unpredictability. A complex web of possible winds, experts say, can create a particularly formidable foe for firefighters.
In British Columbia, changing wind patterns have become a major concern for crews as fires in the southern Okanagan forced the evacuation of hundreds of homes. .
Mary-Ann Jenkins, emeritus professor of atmospheric sciences at York University in Toronto, said fire generally moves in the same direction as the wind blows.
READ MORE: Take a look at some of the wildfires burning across Canada
But mountains can complicate matters. she said.
For example, the Rocky Mountains influence many factors, such as humidity and local wind direction.
Story continues below ad
"Thanks to the Rocky Mountains, the wind can pass through valleys. It changes and it can be very windy downhill,” she said.
"And another thing people don't know is that the winds that go up hills tend to accelerate. As they go uphill, they get stronger and stronger before they reach the top.
Jenkins said the Rocky I said that it creates a unique phenomenon called wind. It can be experienced all year round and can add to the firefighting woes.
"Meteorological conditions at the local level in mountainous areas are difficult to predict because there are so many different types of terrain."
Such unpredictability It's felt sharply around Keremeos in South Okanagan, British Columbia. The region's indigenous name is "Valley of the Three Winds," said Elected Regional Director Tim Roberts.
Story Continues Below Ad
Read More: Keremeos Creek Wildfire There is no timeline as to when evacuees from the home will be able to return home
On Monday, Brian Zandberg, information officer for BC Wildfire Services, said winds around the Keremeos Creek fire were It was weak at about 15 kilometers per hour, and firefighters said they were able to make good progress building containment lines.
But winds could still push the flames south toward the villages of Keremeos and Olala, as happened last week, he said.
"We are making very good profits," he said, but added, "If the wind picks up, it can go where the wind wants it." rice field.
More than 500 homes in the area have been evacuated since wildfires were reported on 29 July.
It's not just the west side of the country where unpredictable winds can be a factor. In Newfoundland, where a state of emergency was declared over the weekend in response to massive fires, changing wind patterns have made it difficult to manage the situation.
Fires that started in an area called Paradise Lake were within 25 kilometers of the town of Grand Falls Windsor. Crew members were working Monday afternoon to create a firebreak to keep the blaze out of town, state forest firefighter Jeff Motti said. Continued below
Meanwhile, in the Northwest Territories, authorities are preventing fires from reigniting on the west side of Lake Marian. was sleeping in the basement.
The Department of Environment and Natural Resources said strong winds from the south were expected to cause extreme fire behavior and a significant spread of the so-called "zombie fires", which stretched over an area of about 65 square kilometers.
READ MORE: Wildfire Activity Expected in August, Experts Say
Thompson Rivers University professor Mike Flanigan said wildfire ingredients include fuels such as grass and other vegetation, hot and dry weather, and wind.
Sometimes it doesn't have to be hot, but it must be dry and windy to start a fire, says British Columbia Predictive Service, Emergency Management, Fire Science. said the study chair.
"Wind is also very important in terms of how it spreads once it's lit," he said in an interview. "It spreads in the direction the wind is blowing. So a westerly wind means that the fire is moving from west to east, and is most violent in the direction of the wind. It's like being pushed by that wind."
Usually, when the temperature drops at night, there is less humidity and less wind, he said.
Story Continues Below Ad
With the warmer weather, he said, winds are "probably" not as calm as they used to be, making it difficult for firefighters. Because of the potential, they tend to create their own winds.
Fires can create vortices of air that swirl along fire lines, she said.
READ MORE: Canadian wildfire season gets off to a calm start cutting. Here's what's on the agenda for this year:
"Sometimes it's pretty harmless, sometimes it's not," Jenkins said. "It spreads fire in a very erratic way and can destroy unexpected homes or overwhelm firefighters."
Story continues below advertisement.
Flanigan said that fire creates cavities filled with rising hot and cold air currents.
"The faster it goes, the stronger the wind," he said. "Wind is the movement of air. Fire creates its own wind field, and the bigger the fire, the fiercer the fire and the stronger the wind."
Even small bonfire sizes , Jenkins said that fire creates its own wind.
"So large fires, on a certain scale, do very interesting things and are quite dangerous. It is a natural aspect of combustion, fuel burning, wildfires."
© 2022 The Canadian Press