Firenado: The Day the NWS Issued a Tornado Warning for a Wildfire

On August 15, 2020, residents near the California-Nevada border received a weather alert that seemed ripped from a disaster movie: a Tornado Warning. But this wasn't a typical storm. The destructive, rotating vortex wasn't born from a supercell thunderstorm, but from the heart of a raging wildfire. For the first time in history, the National Weather Service (NWS) issued a Tornado Warning for a plume of smoke and fire.

Not Your Average Fire Whirl

It’s crucial to understand that this was not a common “fire whirl” or “fire devil.” Those are typically smaller, surface-level columns of rotating air and flame that form within a fire. The event during the Loyalton Fire was something far more powerful and scientifically significant: a true tornado spawned by a fire-generated thunderstorm. Meteorologists refer to this phenomenon as a fire-induced tornado, or more colloquially, a “firenado.” This terrifying hybrid required a specific and volatile recipe of ingredients only a massive wildfire could provide.

How a Wildfire Created a Tornado

The Loyalton Fire was burning with such extreme intensity that it created its own weather system. The immense heat generated a powerful updraft, rocketing a column of superheated air, smoke, ash, and moisture tens of thousands of feet into the atmosphere. This formed a massive, volatile cloud known as a pyrocumulonimbus (pyroCb). This pyroCb was, for all intents and purposes, a thunderstorm born of fire.

On that specific day, the atmosphere above the fire already had the necessary ingredients for severe weather: instability and wind shear (changing wind speed and direction with height). As the fire’s updraft punched through this unstable environment, it began to rotate, forming a mesocyclone—the same rotating core found in tornadic supercells. NWS meteorologists in Reno, Nevada, watched in astonishment as their radar detected strong rotation within the pyroCb, a signature they knew could produce a tornado on the ground.

An Unprecedented Warning

Faced with a rapidly escalating and unprecedented situation, the NWS Reno office made a historic decision. They issued an official Tornado Warning for the area, cautioning of a “dangerous fire-induced tornado” capable of producing winds in excess of 100 mph. The alert warned people to take shelter immediately from both the approaching fire and a tornadic vortex that could launch flaming debris across the landscape. It was a stark acknowledgment that megafires are no longer just fire events; they are extreme meteorological events that can bend the rules of weather as we know them.

A Glimpse into a Fiery Future

The Loyalton Fire’s tornado was a wake-up call. As climate change contributes to hotter and drier conditions, wildfires are becoming larger and more intense. These “megafires” are now powerful enough to regularly generate their own weather, including lightning-producing pyroCb clouds that can ignite new fires miles away. The 2020 firenado demonstrates that the convergence of fire and atmospheric science is creating new, complex dangers that forecasters and emergency responders must now anticipate. It’s a terrifying reminder that in a changing world, even the sky itself can be set ablaze.

Sources

• Instant Weather: What Is A True Fire Tornado And Why Did The NWS Issue A Fire Tornado Alert on August 15, 2020?
• National Weather Service: The Loyalton Fire and Fire-Generated Tornado of August 15, 2020
• The Washington Post: 'Firenado' warning issued in Northern California as huge wildfire spawns rotating smoke plume