The powerful fire and potent rotation inside the wildfire even prompted the National Weather Service in Reno, Nev., to issue what is believed to be the first weather alert of its kind: a “fire tornado warning.”
“Amazing event. Not aware of this ever before,” wrote Neil Lareau, who studies extreme fire behavior at the University of Nevada at Reno. Lareau’s research helped confirm the existence and intensity of the deadly fire tornado associated with the 2018 Carr Fire in Redding, Calif.
Fire tornadoes contain tornadic wind speeds that form when a smoke plume behaves like a thunderstorm. Saturday’s quickly-swelling wildfire produced a smoke plume that towered 30,000 feet high and began spitting out lightning strikes. It also tapped into a change of wind speed and direction with altitude, and began to rotate.
Doppler radar data indicates five or more tornado-strength vortices may have occurred between 1 p.m. and 3 p.m. Pacific time.
Social media videos captured several of the incredible tornadoes, shrouded in amber haze and smoke, and reminiscent of scenes from a horror movie.
At 2:35 p.m., the National Weather Service in Reno issued a tornado warning for parts of Lassen County in northern California, warning that “a pyrocumulonimbus from the Loyalton Wildfire is capable of producing a fire induced tornado and outflow winds in excess of 60 mph.”
“This is an extremely dangerous situation for fire fighters,” read the warning.
Pyrocumulonimbus is the name assigned to a smoke cloud that begins rising and behaving like a typical thundercloud.
Ordinary tornado warnings urge residents to their basements, but an update to Saturday’s special warning was rewritten to replace that call-to-action advice with instructions to follow evacuation orders.
“Do not go into this area! Life-threatening situation!” stated the warning.
Fire tornadoes in and of themselves are rare; being able to detect them in real time on radar is something new.
Wendell Hohmann is the meteorologist at the Reno office who issued the precedent-setting warning. He described it as a “once-in-a-lifetime, career event.”
“We were just trying to get the message out of the extreme fire behavior from this fire given the rotation and the tornadic potential,” Hohmann said. “We figured we could do a severe [thunderstorm warning], but we decided to do a tornado warning to get [the emergency alert system] and [wireless emergency alerts] to activate.”