The Downton Lake wildfire has done some heavy damage throughout British Columbia’s Sea-to-Sky region. According to CTV Vancouver, the fire was first spotted on July 13. It’s now grown to 7,139 hectares, or around 17641 acres. Last week, as the fire continued to burn, an incredibly rare fire tornado was caught on camera in the flames.
As reported by the BC Wildfire Service, a cold front passed through the Gun Lake area, the area where the fire is burning, between 3am and 6am on August 17. Strong winds caused by the front increased the fires growth rate and intensity. The increased fire strength, high winds, and a heavy instability in air mass lead to the creation of this fire whirl.
“Another important factor in the formation of whirls is adequate vorticity, a measure of the atmosphere’s tendency to spin or rotate. Complex terrain, downslope winds and the passing cold front provided the necessary conditions for the formation of this fire whirl over Gun Lake. Fire whirls are an an incredibly rare phenomenon. These unique conditions and extreme fire behavior are not experienced on the majority of fires in B.C.” -BC Wildfire Service
Fire Whirls & Fire Tornadoes
According to the Library of Congress, fire tornadoes, or pyrogenetic tornadoes, are often considered slightly different from fire whirls, though nobody seems to agree exactly how. A fire whirl occurs when hot air and gasses rise from a fire in a spinning vortex column, carrying smoke, flames, and debris. While all fire tornadoes are fire whirls, not all fire whirls are fire tornadoes. For it to be considered both, the event must create its own weather system, further concentrating the rotation.
One that touched down during the Carr Fire in California reached speeds of around 143 mph, making it comparable to that of an EF-3 tornado. Though the actual tornado is pretty rare, small fire whirls can occur in bonfires, or even be created in labs.
Image Credit: BC Wildfire Service via Twitter