Park Fire in California sparks a rare fire tornado

Extreme heat and dry conditions are yielding rare fire behavior — including what some are calling a " fire tornado " — as the massive Park Fire continues to ravage Northern California.

The big picture: Fire tornadoes are still somewhat mysterious but can appear during extreme fire behavior. They have the capacity to intensify heat, spread fire embers and uproot trees.

Threat level: The Park Fire , now the fifth biggest wildfire in California history at over 389,000 acres , exploded in size last week and was accompanied by a rotating, towering cloud of heat, ash and smoke, known as a pyrocumulus cloud.

• A rare rotating plume that's likely a " fire tornado " was soon spotted in the blaze.
• Such columns of rotating smoke and strong winds — which can be capable of causing damage similar to weak or moderate tornadoes — indicate to firefighters that it will be especially difficult to squelch the blaze.

State of play: The fire's rotating smoke plume likely acted as a chimney and sucked in air from surrounding areas.

• Plume-dominated fires typically occur in settings with relatively light winds but plenty of instability in the atmosphere, according to Neil Lareau, an assistant physics professor at the University of Nevada at Reno who specializes in fire weather phenomena.
• Their behavior can be erratic — like spinning into a tornado and creating damaging winds on their periphery.

Yes, but: Exactly how this "fire whirl" or "firenado" happened, and what this phenomena should be called, is a matter of active scientific research.

• They were previously observed in California during the 2021 Tennant Fire in Siskiyou County, 2020 Loyalton Fire near Reno and 2018 Carr Fire in Sacramento Valley, among others.
• The Carr Fire, which killed eight people , produced 143 mile-per-hour winds .

What we're watching: The Park Fire was 18% contained as of Wednesday afternoon and had destroyed over 350 properties and structures.

Editor's note: This story has been corrected to reflect the containment percentage as of Wednesday afternoon (not Thursday morning).