Rare 'fire tornado' springs from blazes spreading rapidly across Northern California

The rare event formed from the Loyalton Fire which has burned more than 20,000 acres north of Lake Tahoe, California since Friday

A rare "firenado" sprung from a California forest fire this weekend and lead the National Weather Service (NWS) to warn residents of "extremely dangerous fire behaviour".

Since Friday, the Loyalton fire has burned more than 20,000 acres north of Lake Tahoe. As of Sunday morning, zero per cent of the forest fire has been contained, according to Tahoe National Forest.

Besides the fire rapidly spreading across Northern California, a rare fire tornado developed briefly on Saturday.

The National Weather Service Office (NWS) issued a tornado warning for the pyrocumulonimbus cloud that formed from the forest fire, warning it showed "extremely dangerous fire behaviour".

A pyrocumulonimbus cloud is created above areas of intense rising heat, like a fire or volcano. A fire tornado, also known as a "firenado", then brings in the smoke, dirt, and fire particles from the nearby fire into its cloud.

Firenados can be dangerous depending on how large they become. In 2018, during the Carr fire in northwestern California, a fire tornado claimed at least two lives.

"Firenadoes are an extreme weather phenomenon that can occur with rotating fire columns," the NWS Reno tweeted. "As extreme as this behaviour is, the #CarrFire had an extreme example of this."

It may have been the first time the NWS has issued a tornado warning for a fire tornado, the San Francisco Chronicle reported.

The blaze formed along Highway 398 and eventually jumped over the road, forcing firefighters to provide protection to drivers in the area.

The cause of the Loyalton fire is under investigation. California has experienced a record-breaking heat wave this past week with temperatures reaching the triple digits. Low humidity in the air has also made for drier conditions, causing problems for firefighters as they fight the blaze.

A red flag warning was issued for the San Francisco Bay Area and other parts of Central California through Sunday morning due to critical fire conditions.

Fire officials are also battling wildfires in California, Colorado, and Oregon, as the West Coast experiences high temperatures. One fire in the Los Angeles area has raced across more than 17,000 acres so far and was only 12 per cent contained.