Authorities warn that the unprecedented ferocity of Australia’s wildfires can produce extreme weather systems — dangerous and unpredictable conditions known as cumulonimbus flammagenitus, or pyrocumulonimbus (pyroCb) clouds. These pyroCb are associated with fire clouds, ember attacks, fire-driven tornadoes and lightning storms that could create further wildfires. Australia’s Climate Council advisory says that these occurrences are likely to become more common as climate change persists and greenhouse gas emissions increase. Even more worrisome, pyroCb can make firefighting efforts more difficult.
“A fire-generated thunderstorm has formed over the Currowan fire on the northern edge of the fire near Nowra. This is a very dangerous situation. Monitor the conditions around you and take appropriate action,” the New South Wales Rural Fires Service (NSW RFS) recently shared via social media.
NSW RFS Commissioner Shane Fitzsimmons brought attention to the situation when an RFS firefighter died because of the wildfire-associated bizarre weather phenomena. “That extraordinary event resulted in a cyclonic-type base flipping over a 10-tonne truck. That is the volatility and danger that exists,” Fitzsimmons explained.
According to a Climate and Atmospheric Science journal study, wildfire-triggered thunderstorms, or pyroCb, have been observed before in other regions of our planet and were first discovered in the early 2000s. They were originally thought to have been precipitated by volcanic eruptions until they were reclassified as being wildfire-induced. The study of wildfire-associated pyroCb is still a nascent science, yet to be systematically researched.
In recent years, the University of Wisconsin-Madison’s Cooperative Institute for Meteorological Satellite Studies (CIMSS) has monitored pyroCb in cooperation with both the National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA). CIMSS classifies pyroCb as a “deep convective cloud…generated by a large/hot fire.” CIMSS has been monitoring the pyroCb formations above Australia as the wildfires continued to grow in quantity and magnitude.
Several factors make pyroCb a formidable atmospheric force. The speed at which they form and change, coupled with heat from wildfires, can cause rapid, massive temperature swings. In turn, this fosters unpredictably severe winds that exacerbate wildfire intensity. The dynamics of pyroCb and their destructive power can, therefore, put the lives of both firefighters and the public at risk.
“PyroCb storms are feared by firefighters for the violent and unpredictable conditions they create on the ground,” The Guardian reported. Not only are pyroCbs capable of creating lightning strikes and hail, but they can also engender embers that are “hot enough to start new fires…at distances of 30km from the main fire.”
Dr Andrew Dowdy, a meteorologist at Australia’s Bureau of Meteorology, adds that the increase of greenhouse gases in the atmosphere and the resultant climate crisis facing our planet makes conditions favorable for pyroCb.
As Simon Heemstra, manager of planning and predictive services at NSW RFS, said, “What’s happening now is that we are noticing an increase in incidence of these sorts of events. With a changing and heating climate, you are going to expect these effects.”