See How the Dixie Fire Created Its Own Weather
This year’s largest blaze generated powerful storm clouds. We show you in 3-D.
See How the Dixie Fire Created Its Own Weather
This year’s largest blaze generated powerful storm clouds. We show you in 3-D.
Oct. 20, 2021
Days after California’s Dixie fire ignited in mid-July, towering storm clouds burst from the flames, generating lightning and wild winds that pushed the fire “in every direction,” according to firefighters battling the blaze.
The storm — an early sign of Dixie’s devastating potential — was part of a broader outbreak of extreme fire behavior across the West this summer.
From California to Canada, the landscape was primed to burn: A severe drought and high summer temperatures magnified by climate change left vegetation tinder-dry, with low humidity and strong winds further amplifying the risk. Given a spark, new fires grew explosively. Several became so large and intense that they powered their own weather systems, spawning towering storm clouds, lightning and even some “fire whirls,” spinning vortices of flames.
Now, for the first time, you can see one of these firestorms up close.
Using high-resolution radar data, which picked up ash particles from smoke plumes and water droplets from clouds, The New York Times reconstructed a 3-D model of the Dixie fire’s first massive thunderclouds.
The Dixie fire had already burned through more than 30,000 acres of densely forested land in less than a week, when on July 19 things took a turn for the worse.
Feasting off of abundant dry fuels, the fire intensified, spewing plumes of smoke and rapidly heating the air above it, which began to quickly rise.
The strong updraft funnelled smoke and heat into the atmosphere like a chimney.
There, moisture began to condense around tiny smoke particles, forming puffy white clouds.
Soon, the fire clouds grew into an extreme form: Pyrocumulonimbus, or pyroCb, for short — a fire-fueled thunderstorm.
The storm unleashed nearly a dozen lightning strikes over a roughly hour-long stretch.
Like regular thunderclouds, pyroCbs generate wind and lightning, increasing the risk of spreading a fire, but they don’t often produce significant rain.
The storm’s towering, anvil-shaped clouds reached more than 40,000 feet into the air, well above the typical cruising altitude of a passenger plane.
Neil Lareau, an atmospheric scientist who advised this project, called the firestorm a “watershed moment” for the Dixie fire and an early sign of its destructive power.
Eventually, the storm clouds began to rain, pushing moisture and strong winds to the surface.
The dry, thirsty atmosphere sucked up much of the moisture before it reached the ground. But the winds continued to descend, fanning out across the terrain.
To the northwest, a new pyroCb cloud abruptly shot up. The downburst winds may have helped push Dixie’s flames into a new pocket of fuel, Dr. Lareau said, kicking up more fire clouds.
By late afternoon, the firestorm finally lost steam and the clouds began to dissipate. But the Dixie fire continued to stir up powerful storms as it grew into the largest blaze of the year.
Over its lifespan, the Dixie fire generated eight firestorms and displayed other extreme behaviors, including at least one fire whirl, a sort of mini-tornado. David Peterson, a meteorologist who tracks fire-driven thunderstorms at the U.S. Naval Research Laboratory, called Dixie “the most prolific producer of pyroCbs” in the United States this summer.
These storms create “a very dangerous situation for our firefighters on the ground,” said Edwin Zuniga, a public information officer for Cal Fire, California’s firefighting agency.
When wildfires are driven by wind, they usually move in a predictable direction. “If the wind is blowing from the southwest, we know the fire will be travelling to the northeast,” Mr. Zuniga said. But fires that are “plume-dominated” — like those creating and sustaining their own weather systems — are more volatile. They spew their own erratic winds and can throw embers long distances, causing spot fires miles away.
Faced with pyroCb clouds, firefighters are usually forced to pull back from a blaze. “It’s really nearly impossible to contain at that point,” Mr. Zuniga said.
Since it began in July, when a small cluster of flames was discovered near downed power lines, the Dixie fire has burned through nearly a million acres across the Sierra Nevada, triggering mass evacuations and destroying thousands of homes, businesses and other structures, including much of the town of Greenville.
Today, the fire is almost fully contained, though pockets still smolder.
Competing forces helped Dixie grow into a monster, said Ryan Bauer, a fire manager at Plumas National Forest. Strong winds often pushed flames across the rugged terrain of the Sierra. But even when the winds were calm, the fire created its own momentum, kicking up powerful plumes and pyro-clouds.
Recent extreme heat and drought had turned California’s overgrown forests into potent fuel for either scenario. “The stage was set for fire to spread no matter what the conditions,” Mr. Bauer said. “It was just a matter of whether it was going to be wind-driven that day or plume-dominated.”
Sept. 12
Eagle Lake
Sierra Nevada
CALIFORNIA
Aug. 6
Dixie fire
Chester
Janesville
Lake Almanor
Honey Lake
Aug. 6
Almanor
Dixie
fire
July 24
Greenville
July 24
Sept. 12
July 19
Aug. 31
CALIF.
July 17
70 MILES
Sept. 12
Sierra Nevada
CALIFORNIA
Aug. 6
Dixie fire
Chester
Janesville
Aug. 6
Almanor
Dixie
fire
July 24
Greenville
Sept. 12
July 24
July 19
Aug. 31
CALIF.
July 17
70 MILES
Sept. 12
Sierra Nevada
CALIFORNIA
Aug. 6
Dixie fire
Aug. 6
Dixie
fire
July 24
Sept. 12
July 24
July 19
Aug. 31
CALIF.
July 17
70 MILES
CALIFORNIA
Sept. 12
Dixie
fire
CALIF.
Aug. 6
Dixie fire
Aug. 6
July 24
Sept. 12
July 19
Aug. 31
July 17
70 MILES
Wildfires on the West Coast have grown larger and more intense in recent years, especially in California. Experts attribute the trend to a combination of factors, including decades of aggressive fire suppression that left forests dangerously overgrown, and climate change, which has parched the landscape, priming it to burn at record scale.
Fire clouds have also become increasingly common on the landscape. In California, where powerful infernos have burned close to population centers, snapshots of the mushroom-like clouds have spread widely on social media.
Dr. Peterson’s team recorded 33 pyroCb clouds in the American West this year, tying a record set in 2013.
Aug. 13, 2021
OREGON
PyroCb
cloud
Antelope fire
Dixie fire
McFarland fire
CALIFORNIA
Aug. 13, 2021
OREGON
PyroCb
cloud
Antelope fire
Dixie fire
McFarland fire
CALIFORNIA
It’s not yet clear whether there is a sustained long-term trend toward more fire-fueled storms, in part because the record of these events is still relatively short: An effort to consistently track pyroCb formation across the globe, based on satellite observations, dates back about a decade.
What is clear is that the ingredients necessary for firestorm activity — drier landscapes that support larger, more intense fires; more atmospheric instability, which aids the development of thunderstorms; or both — are becoming more common in many parts of the world as human-caused climate change pushes temperatures higher.
Following a historic heat wave early this summer, Western Canada experienced a particularly explosive run of pyroCb activity. On two occasions, the powerful storm clouds grew so tall — the largest reached an altitude of 57,000 feet — that they broke through the lower atmosphere and injected smoke into the stratosphere. The smoke particles can linger in this layer for months and make their way around the globe, which can even lead to some temporary regional cooling.
Firestorm clouds have regularly been documented in Western North America, Southern Australia and across much of Siberia, where wildfires are seasonal events. But extreme fire weather is now occurring in less expected places, too: A pyroCb cloud formed north of Athens this year, part of a disastrous outbreak of summer wildfires.
“We're creating an environment that favors these positive feedbacks, where the fire makes itself worse,” said Dr. Lareau, an assistant professor at the University of Nevada, Reno. “It tips the balance between what may have been an ordinary fire in decades past and a fire that can grow into a megafire.”
Augmented Reality
How Wildfire Smoke Can Reach the Upper Atmosphere
This augmented-reality experience shows how wildfires generate enormous storm clouds. In a 3-D map, see how giant wildfires push smoke through the atmosphere like a volcanic eruption. To experience this effect in your space, you will need the Instagram app.
To view on Instagram, open the camera on your device and point to the QR tag below.
Experience in ARHow we built the 3-D model
The Dixie fire’s smoke and clouds were created using reflectivity data from three Next-Generation Radar network stations collected on July 19, 2021, between 11:00 a.m. and 11:00 p.m, Pacific Daylight Time.
The raw data was collected every 10 minutes in radial sweeps around the radar stations, each at a higher altitude. The Times combined and reformatted the data using Py-ART, a collection of algorithms and utilities used regularly in radar analysis. We then filtered it to reduce noise.
We applied color and texture to the 3-D volume to approximate a smoke- and cloud-like look. And we interpolated the sequence in time to create a smoother video animation.
The radar volume rendering was based on previous work by Dr. Lareau of the University of Nevada, Reno.
The lightning strikes were recorded by the Vaisala Lightning Detection System. We only showed strikes that reached the ground.
The terrain was created using topographic data from the U.S.G.S. 3-D Elevation Program and color imagery from the Copernicus Sentinel-2 satellites, retrieved at a resolution of 10 meters. To eliminate 2-D cloud cover on the landscape, we generated a composite of satellite images from June 1 to June 30, 2021.
The fire footprint was created by combining perimeter data from the California Department of Forestry and Fire Protection along with fire detections data from NASA's Fire Information for Resource Management System and the U.S. Forest Service Active Fire Mapping Program.
Additional expert sources
• Michael Fromm, meteorologist at the U.S. Naval Research Laboratory
• Daniel Swain, climate scientist at the University of California, Los Angeles
• Rich Thompson, incident meteorologist at the National Weather Service, Los Angeles/Oxnard
Additional credits
Produced by Michael Beswetherick
Photo editing by Matthew McCann
Additional work by Or Fleisher, Sam Manchester and Jeremy White
Top video from ALERTWildfire and PG&E