The bushfires in Australia are creating violent weather systems that can spark new fires, conjure fire tornadoes and make fighting existing fires much more challenging, experts say.
The rising heat from the intense bushfires creates massive, powerful clouds called pyrocumulonimbus, or pyroCb. These "fire clouds" are created "when fires loft enough heat and moisture into the atmosphere" to produce smoke-infused thunderstorms, according to the NASA Earth Observatory.
Mike Fromm, a meteorologist at the U.S. Naval Research Laboratory who has researched these clouds extensively, said he likens the process to a volcanic eruption.
"They are a combination of a regular thunderstorm that everybody is very, very familiar with, but with the explosive heat source from the fire which actually makes them very peculiar," Fromm said.
This weather phenomenon adds to the harrowing scenes that Australia has been facing since the fires started in September. Lightning strikes from the storms could also spark new fires, potentially adding to a situation that officials are saying could take months to extinguish.
Craig Clements, a professor and director of the Fire Weather Research Laboratory at San Jose State University, said updrafts in these clouds can reach speeds of well over 100 mph. He said his research team flew an aircraft through a pyroCb cloud over Idaho in 2016 and measured updrafts of 135 mph with an airborne radar. This research is contained in a paper that is not yet published, he said.
About 20 "pyroCb pulses" have occurred over Victoria and New South Wales in the past week or so, Fromm said. On a scale of very minimal to major, five to eight of these pyroCb events have been in the major category, he said.
The tallest of these reached almost 10 miles high, according to Fromm.
The Bureau of Meteorology in Australia tweeted on Saturday a rapid scan animation that shows smoke from the New South Wales and Victoria fires in Southeast Australia creating these thunderstorms.
The New South Wales Rural Fire Service also tweeted out on Saturday a video of the "pyrocumulous clouds forming" above the Currowan fire.
The volunteer-based firefighting agency warned its followers on Twitter that same day of a "fire-generated thunderstorm," describing it as "a very dangerous situation."
A firefighter from the agency was killed a little over a week ago by what local crews at the scene described as a fire tornado caused by what they believe was the collapse of a pyroCb cloud formation, Shane Fitzsimmons, the New South Wales Rural Fire Service commissioner, said in a press conference. The collapsed formation rolled over the fire truck the firefighter was in.
"[The collapse] resulted in cyclonic-type winds that has moved across the fire ground and has literally lifted up a 10- or 12-tonne firetruck and flipped it onto its roof trapping the people inside," Fitzsimmons said.
NASA describes the clouds as the "fire-breathing dragon of clouds."
Fromm said these clouds act like a chimney in that all the smoke gets shot directly upwards and actually suppresses precipitation, making it more vigorous than a regular thunderstorm.
"If that precipitation never occurs then you get nothing to slow it down or to reverse it and so all of that material that's going up goes up much more efficiently," he said.
The bushfires creating these weather events are fueled by drought. The fires started several months earlier than is typical for Australia's annual wildfire season as the country suffers through its hottest and driest year on record.
So far, more than two dozen people have been killed and 2,000 homes destroyed. Hundreds of millions of animals are believed to have been killed in the blazes as well.
An area twice the size of Maryland has been scorched. New South Wales is getting hit the hardest, as 130 fires were still burning Tuesday, 50 of which were considered uncontrolled.
The beginning of this week brought cooler, rainier weather, but it wasn't enough to snuff out the fires that continue to rage.
— The Associated Press contributed to this report.