A massive fire cloud known as a pyrocumulonimbus formed over a fire in Northern California. The funnel appeared in a thick plume of smoke from the Loyalton Fire in Lassen County, Calif. on Saturday, Aug. 15, 2020. A wildfire in Northern California on Saturday spawned at least one fire tornado that prompted the National Weather Service to issue a tornado warning. The Loyalton Fire in Lassen County, Calif., burned intensely amid hot and dry conditions on Saturday afternoon. The National Weather Service said this firenado was capable of producing outflow winds as strong as 60 miles per hour.