'Fire tornado' caught on camera by crews fighting B.C. blaze

An "incredibly rare" phenomenon called a fire whirl or fire tornado was caught on video by ground crews responding to a destructive blaze last week, according to the B.C. wildfire service.

Conditions in the early morning hours of Aug. 17, which included a sudden drop in temperature following a heat wave combined with whipping winds, caused the Downton Lake wildfire to display behaviour that is rarely seen in the province.

Video of the vortex was posted online Tuesday, along with an explanation.

"The combination of high fire intensity, strong winds and air mass instability resulted in the formation of a fire whirl (otherwise known as a fire tornado) over Gun Lake. Fire whirls are vertically oriented, intensely rotating columns of gas and flame," the Twitter thread from the BCWS says.

"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."

The Downton Lake wildfire continues to burn out of control. It is confirmed to have destroyed properties and while officials have said that the losses have been "significant" they also said they have been unable to access the hardest-hit areas to confirm how many properties were damaged or destroyed.

The fire whirl came as a cold front swept across swathes of the province, fuelling explosive growth on a number of fires that triggered a cascade of evacuation orders and alerts and left devastation in its wake.

As of Tuesday, thousands remain out of their homes and thousands more remain on evacuation alert.

A province-wide state of emergency remains in effect.