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How wildfires can spawn lightning and tornadoes

Wildfires can create their own weather systems that can produce lightning, hail, and tornadoes.

GRAND JUNCTION, Colo. — The sound of thunder echoed through the Grand Valley early Wednesday morning. There's nothing too unusual about that in the summertime, but this lightning was triggered by a very unusual thunderstorm – a Pyrocumulonimbus or fire thunderstorm. 

It was the spawn of the Pine Gulch fire that’s been burning on the western slope of Colorado since July 31.

Full 9NEWS coverage of wildfires in Colorado can be found here.

Wildfires have the ability to create their own weather. Here’s how it works.

It starts with the heat and smoke above the fire rising high into the atmosphere. 

There it mixes with cooler air which causes cloud condensation. Sometimes that cloud can evolve into a full-blown thunderstorm, usually referred to as a pyrocumulonimbus.  

The Pine Gulch fire has been creating these on a regular basis. The signature appearance of a billowing dark-brown plume of smoke has been seen rising above the flames, with that cloud gradually transitioning into a more white and puffy cloud that has a cauliflower look to it. That is wildfire smoke turning into a thunderstorm. 

A pyrocumulonimbus is capable of producing the same hazards seen in regular thunderstorms like rain, hail, lightning, microbursts, and even tornadoes.

On Saturday, the National Weather Service in Reno, Nevada issued the countries first ever tornado warning for a fire tornado. A pyrocumulonimbus over the Loyalton fire in California created the tornado.

They are similar to fire whirls, like this one created by the Pine Gulch fire last week. They are created by temperature and pressure differences at the surface, but if a fire whirl was to get pulled into a pyrocumulonumbis and come in contact with the storm, it would then become a rare fire tornado, or as they are sometimes called firenadoes.

Credit: Kyle Miller - Wyoming Hotshots
A fire whirl is seen as fire crews battle the Pine Gulch fire. (Photo courtesy of Wyoming Hotshots)

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