KEY POINTS

  • Pyrocumulonimbus clouds can create dry lightning and trigger very hot winds on the ground
  • The NSW last week spotted what appeared to be a pyrocumulonimbus cloud around the Bootleg fire
  • The Bootleg Fire has burned more than 300,000 acres and is the biggest burning fire in the country

Oregon’s wildfires are still blazing on, and meteorologists are watching out for the potential creation of a feared mega-fire cloud, known as the pyrocumulonumbus cloud, that could further fan the flames.

The pyrocumulonumbus cloud is a rare phenomenon compared to the pyrocumulus clouds. The latter, more commonly known as “fire clouds,” are giant, dark-colored thunderheads on top of a huge column of smoke. These clouds form on top of smoke billowing up from wildfires. The top of these cloud formations take the form of an anvil, USA Today reported.

The pyrocumulus clouds are being regularly witnessed across the fires burning in Oregon, especially around the biggest burning fire in the U.S., the Bootleg Fire.

However, meteorologists are more concerned about the possible formation of the pyrocumulus cloud’s “big brother,” the pyrocumulonimbus cloud that creates its own weather.

This particular cloud formation is so hot and massive in size that it can create dangerous hot winds on the ground if a “fire tornado” is spawned from the cloud. The cloud can also produce thunderstorms. NASA has dubbed the pyrocumulonimbus cloud as the “fire-breathing dragon of clouds” as it could produce its own dry lightning that could further trigger wildfires.

Idaho Gov. Brad Little last week warned of the potential for multiple such "mega-fires" and appealed to the public to help prevent them. Such fires could eat up any resources thrown at them and also can be extremely dangerous to the firefighting crews.

Nearly 600 square miles have been burned by the Bootleg Fire and it has produced pyrocumulus clouds, albeit less intensely hot ones. Worryingly, last Wednesday, the National Weather Service said it detected what appeared to be a pyrocumulonimbus cloud in “terrifying” satellite images around the fire.

No deaths have been linked to the Bootleg Fire yet, but around 5,000 homes are threatened by the fast-growing blaze.

So far, the Bootleg Fire’s size has reached 476 square miles (approximately 1,210 square kilometers). It has burned at least 70 homes, the Associated Press reported. Over the weekend, ground crews were forced into retreat for the ninth consecutive day as the Bootleg Fire’s size and intensity put workers in danger.

The Bootleg Fire and other big fires in Oregon have caused fuel-related flight cancelations at the Bozeman Yellowstone International Airport in Montana, CNN reported.

In an emailed statement to the outlet, airport director Brian Sprenger said that fuel deliveries were delayed Sunday due to the “increased fire suppression needs throughout the West.”

There has also been a shortage of transport drivers not just in Oregon but also across the country.

As of Monday morning, the Bootleg is burning more than 340,000 acres and has only been contained at 25 percent.

Smoldering trees in the Bootleg Fire on July 17, 2021 near Klamath Falls, Oregon Smoldering trees in the Bootleg Fire on July 17, 2021 near Klamath Falls, Oregon Photo: US Forest Service / Handout