- Your Town
Spreading the word about a new fire phenomenon
Red Lodge Fire Department’s Wildfire Awareness Open House listened to a talk given by Australians Jason Sharples and Bob Cechet about experiences they’ve had and witnessed in their own country regarding fires.
Sharples is an associate professor at the University of New South Wales, and a rural fire fighter for the Gungahlin Brigade, a volunteer branch of the Australian Capital Territory State. Cechet is an adjunct professor University of New South Wales and Project Leader for the Environmental Geoscience Division, Geoscience Australia.
Both have written several books and papers on fire behavi o r and c l imat e change.
Sharples spoke to the assembled group about two phenomenon called foehn winds and vorticity-driven lateral fire spread.
The first involves stronger winds blowing from the mountains resulting in abrupt rises in temperature, and abrupt decrease in relative humidity.
The second, which Sharples concentrated on more, is to do with fires not being dictated to by the prevailing wind.
Using as his example Sharples chose the Jan. 18, 2003, McIntyre’s Hut Fire, Canberra.
“Despite the fact that winds were west north west, look at the fire’s lateral development, almost 90 degree, spreading perpendicularly to the wind,” he said, showing slides of the fire.
“It’s happening on lee facing slopes. Traditional wisdom is this is where you get in and cut your tracks around it. This won’t work if you have one of these. The concept of a fire front goes out the window. You’re talking more about a thunderstorm not a fire. A pyrocumulonimbus has everything except for the rain, mostly embers. And the presence of dark smoke denotes advancing flames.”
These effects were noted in 2006, and metrologists didn’t think the mountains were big enough in Australia for these to occur but occurring they are. Sharples believes these could be possible because of climate change.
He has even conducted experiments to prove this theory, and all tests have shown the movement of fire against the wind.
“These fire are having our lunch,” he said.
“We’re looking at systems to manage the risk and how communities deal with this. Trying to understand the more extreme processes that lead to small fires grown into bigger ones and quickly,” said Sharples.
Sharples said “we take as much data as we can and try to find out what drives them and then generate maps in landscapes where this is likely to happen and give these to management teams. “
Captain Jon Trapp, Red Lodge Fire Rescue, felt the talk was “good.”
“It's good to get perspectives from other areas in the world. The main thing I took from their talk was to be aware of a new phenomenon regarding fire behavior,” he said. “Rapid fire spread perpendicular to the wind is not typical with wildfire. We are often trained to engage the fire from the flanks, which is usually safer. This new fire behavior, which can possibly be attributed to climate change, can put many firefighters in danger. We need to be aware of the circumstances in which this fire behavior could occur and change our tactics if needed.”