Like a scene out of an apocalyptic movie, a raging California wildfire pumped out a monster cloud towering 40,000 feet into the atmosphere on Thursday. As the Mosquito Fire tore across Tahoe National Forest, making a 5,000-acre run across the American River and pushing into the El Dorado County town of Volcanoville, the cloud grew and grew.
At one point on Thursday afternoon, the Mosquito Fire belched out a second cloud, and twin plumes rose above the blaze.
From miles and miles away, people on the ground caught sight of the monster clouds, with many posting astonishing images on social media. Alan Brewer, a scientist with the National Oceanic and Atmospheric Administration, got a much closer look from a plane with a team of scientists who were flying along the side of the massive wall of sooty air to better understand fire behavior and its impacts.
“It really hit everybody in the plane pretty hard just how massive and destructive the fire was,” Brewer told SFGATE on the phone. “It was like flying right alongside the wall of the Grand Canyon.”
These so-called pyrocumulus clouds are formed when air around a fire heats up, creating an updraft that pushes smoke, ash and moisture upward. They usually appear over a fire in the afternoon, when daytime temperatures peak and afternoon winds pick up. When fires are especially large, the clouds can grow so high into the freezing-cold atmosphere that ice crystals form in the top layer. These larger pyrocumulonimbus clouds can generate their own weather, including lightning, hail and strong winds. The clouds generated by the fire on both Wednesday and Thursday fell into this category. Both of these types of clouds are a sign of severe fire activity and growth on the ground.
But on Friday afternoon, no cloud formed because of a shift in the weather and a temperature inversion, which acted as a cap, trapping smoke close to the surface. The Mosquito Fire, which first ignited on Tuesday near the Placer County town of Foresthill, grew minimally on Friday.
Brewer and researchers from San Jose State University’s Fire Weather Research Laboratory and the University of Nevada have traveled to the scenes of fires around California, such as the Mountain Fire in Siskiyou County, since August. He and the other scientists are part of a project called the California Fire Dynamics Experiment, which is looking at the way fire and atmospheric processes feedback on one another to generate extreme wildfires.
“This was by far the largest fire we’ve done,” he said. “We look at the dynamics around the fire, the heat, we’re taking infrared images of the fire to look at spread and then we’re looking at the chemistry and the emissions coming from the fire.”
With the Mosquito Fire, he said the NOAA Twin Otter plane had to fly along the sides of the plume and couldn’t travel over the top because the cloud was too tall.
“We’re trying to understand fire behavior,” he said. “Ultimately, it’s to improve models that predict fire behavior as well as air quality models. We’re taking measurements to improve those models.”
The project also has scientists on the ground observing and taking measurements of the clouds. Neil Lareau, an atmospheric scientist and professor at the University of Nevada, was less than a mile away from the Mosquito Fire’s edge on Thursday.
He was also wowed by the cloud’s size, though he said it wasn’t quite as big as the 50,000-to-55,000-foot-tall pyrocumulonimbus cloud that formed above California’s 2020 Creek Fire as it devoured 379,895 acres in Fresno and Madera counties.
While these clouds turning into breathing monsters shooting out lightning and intense gusts of wind used to be an unusual phenomenon in California, Lareau said they’re becoming more common due to parched, overgrown forests and a changing climate.
“Fires like this are suddenly feeling kind of normal,” he said. “The Caldor Fire, the Dixie, the Creek … these are just a few recent examples of fires that behaved like this.”
Lareau said the team was able to make some “new unprecedented level of observations” on Thursday as the cloud grew so powerful that it churned like a vortex spewing whirls of fire.
“There was a very strong fire-generated vortex that extended from the surface and generated winds equivalent of an EF1 tornado,” he said.