An 鈥渋ncredibly rare phenomenon鈥� during a wildfire near Lillooet was caught on video last week.

The fire whirl, or 鈥渇ire tornado,鈥� was caught on video by an overnight ground personnel responding to the Downton Lake wildfire on Aug. 17. Fire whirls are 鈥渋ntensely rotating columns of gas and flames,鈥� BC Wildfire Service explained in a series of tweets Tuesday (Aug. 22).

A cold front passed through the province Aug. 18 after several days of dry hot weather and when it passed through the Gun Lake area in the Bendor Range Complex fires near Lillooet it resulted in the 鈥渇ire tornado.鈥�

The 鈥渦nique conditions and extreme fire behaviour鈥� are not experienced in the majority of B.C. wildfires, but BC Wildfire Service explained the conditions that led to the 鈥渇ire tornado.鈥�

There were strong winds from the southwest, resulting in significant fire growth and intensity, the relative humidity value of 14 per cent at 4 a.m. that BC Wildfire said was 鈥渋ncredibly rare to see overnight鈥� and a reduced measure of how much moisture was in the air of -11 C.

BC Wildfire Service said it was a significant drop 鈥� 20 C lower than the day prior to the cold front.

鈥淲ith this combination of conditions and fire behaviour, fire intensity was more extreme during this overnight period, reaching intensities that hadn鈥檛 been seen even during the day.鈥�

With the combination of high fire intensity, strong winds and air mass instability, it led to the formation of a fire whirl over Gun Lake.

Another important factor in the formation of whirls is adequate vorticity, a measure of the atmosphere鈥檚 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.

鈥� BC Wildfire Service (@BCGovFireInfo)

lauren.collins@blackpress.ca
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