As the Western United States continues to bake and burn, satellites are capturing dramatic imagery of large infernos that so far have incinerated more than a million acres.
Under extreme conditions on July 13th, the largest of the blazes, Oregon's Bootleg Fire, grew to more than 200,000 acres. That's equivalent to the land area of New York City. As I'm writing this on July 14th, the blaze has grown by another 12,000 acres, thanks to hot, dry and breezy conditions.
The Bootleg blaze is seen in the image above, which is itself a screenshot taken from this video:
Visible and infrared image data, acquired by the GOES-17 satellite on July 12, 2021, are used in the animation to show areas of active burning and smoke. As you watch it, look for white puffs erupting out of the thick gray plumes. These are gigantic fire clouds, known scientifically as "pyrocumulus."
Here's another animation of GOES-17 imagery, acquired today, showing fire clouds erupting from the Bootleg and other fires:
The Bootleg blaze is toward the upper center of the frame. Once again, look for white puffs that explode out of the smoke.
Pyrocumulus clouds form as intense heat sends large amounts of water vapor erupting upward in soaring updrafts. As the rising water vapor cools, it condenses into water droplets around little particles. With so much smoke and ash present, there are lots of these condensation nucleii available to help spur on the process.
The upshot: Enormous amounts of smoke and moisture boil up into towering clouds that can punch through the lower atmosphere into the stratosphere, all the way up to heights exceeding 30,000 feet.
You can get a sense of how it all gets started from this image of the Bootleg fire taken on July 7th.
When there is enough heat and moisture available, pyrocumulus clouds can boil up so vigorously that they crackle with lightning and boom with thunder. These fire thunderstorms are known as "pyrocumulonimbus," or "pyroCb" for short.
As NASA puts it, "pyrocumulonimbus is the fire-breathing dragon of clouds." And not just because of the firey origins of the phenomenon, but also because of the lighting hurled toward the ground by these storms, which can ignite new fires.
Impact of Climate Change
Many studies have shown that climate change has led to increases in the length of the wildfire season, the frequency of fires, and the amount of land burned. These trends are linked to warmer springs, longer summer dry seasons, and drier soils and vegetation.
Of the 10 years with the largest amount of land burned, all have occurred since 2004, including the peak year of 2015, data from the National Interagency Fire Center shows. Many of the warmest years on record nationwide have occurred during this same period.
In the West, the burned acreage has increased in nearly every month of the year.
As of today, 68 large fires are burning across the United States, all but one in the western states. Ten new large fires were reported yesterday in Arizona, California, Idaho, Montana, and Oregon, according to the National Interagency Fire Center. Another four have been reported today. (For the latest statistics from the NIFC, go here.)
All told, 16,650 wildland firefighters and support personnel are working to contain the fires. More than 2,700 of them are battling northern California's Beckwourth Complex, which consists of two wildfires sparked separately by lightning. They are blazing near each other in California, north of Lake Tahoe. Some 92,988 acres have burned so far.
The Beckwourth Complex is seen In the image above, acquired by the Sentinel 2 satellite on July 10th. The body of water visible in the image is Nevada's Pyramid Lake.
Smoke from fires burning in Oregon, California and other parts of the West has obscured the skies in a vast swath of territory, including in New Mexico and Colorado. I shot the smokey sunset photo above on July 12th while pulled over on the shoulder of U.S. Route 285 in the northern part of Colorado's San Luis Valley.
Millions of people across the country may experience similarly smokey sunsets, as this smoke forecast shows:
Unfortunately, it looks like the West is going to continue to suffer for awhile. As Washington Post meteorologist Matthew Cappucci puts it:
"It’s happening. Again. For the fourth time in five weeks, a punishing heat wave is set to bake the West and adjacent western Canada."
The central and northern Rockies will see the most exceptional heat, which will peak early next week, according to Cappucci. "The heat wave is forecast to bring triple-digit temperatures to at least 17 million people, challenging and breaking records into Canada."
Looking much further ahead, the Southwest recently received some additional bad news: Forecasters say a new La Niña is likely to emerge during the September-November period and last through next winter.
The climate phenomenon probably contributed to the historic drought currently gripping the Southwestern United States. It's not uncommon to have two La Niña winters back-to-back, and that's precisely what observations and modeling are now suggesting will happen.
But that's the topic for a future post. Stay tuned...