When wildfires happen, we use models to predict how they will spread. However, these models are missing critical information, such as how wildfires can make themselves stronger by changing the weather. Without understanding this, we could be putting people and property in danger, especially as the climate crisis intensifies.
Many parts of the world are expected to have warmer springs and longer summer dry seasons, which means that forested areas are more likely to dry out, making it easier for fires to start. What’s more, with more people moving into wildland areas, these fires are more likely to put human life at risk, and fighting wildfires can be much more difficult than fighting house fires.
Wildfires often start in remote areas and can become massive very quickly. This means that, in order to fight fires safely, firefighters need to know how, when, and where any individual fire is likely to spread. To figure this out, they use complex computer models which take into account the type of terrain the fire is burning in and how much fuel the fire has access to. However, in our current wildfire landscape, this just isn’t good enough.
We need to figure out what else affects wildfires, so that we can update our models. One of the most important factors to consider is the weather; strong winds can snuff out small fires, but only enhance larger fires by literally fanning the flames. Fires are likely to travel in the same direction as the wind, and prevailing wind patterns can push fires in one direction, keep them in place for longer, or even split them into two separate fires.
While we do incorporate wind forecasts into our models, these forecasts look at how wind blows on a large scale, such as atmospheric fronts or enormous storm systems. They don’t look at wind patterns on small scales, like how wind can curve around a mountain, or how a narrow path between two peaks can become a wind tunnel; this happened in the Redwood Valley Fire in 2017. Weather models failed to take into account a small 11 kilometer Gap in the mountains of Northern California, but the wind did not. Winds rushed through the Gap creating a small wind tunnel that carried the fire along with it in 2018. Winds coming downslope from the nearby mountains pushed a fire into the town of Paradise California, killing 85 people and virtually destroying the town. Wind can also pick up Embers and carry them far away from the main fire, and if those Embers find the right conditions, they can flare up into new wildfires. This means an updated fire model will have to pay attention not only to which way the wind is blowing, but also where Embers could land and whether those Embers are likely to form new fires.
Strong winds can also change the weather in their favor. Fires cause plumes of hot air and smoke to rise, and when the fire is large enough, those plumes can get pretty far into the atmosphere. When the plumes hit cooler air in the high levels of the atmosphere, they cool down, and water vapor condenses out of them forming storm clouds. These clouds are common enough features of large fires that they have their own name; usually they’re referred to as pyrocumulonimbus clouds. Unfortunately, unlike most storm clouds, these clouds don’t tend to release a lot of rain, and when they do, it can sometimes make fires worse. When rain falls into dry air, it evaporates, creating a sudden burst of cooler air. This change can affect the wind patterns, creating down bursts around the Flames, which can spread Embers causing new ignitions farther away from the fire.
The plume that formed the cloud in the first place would have also altered wind patterns, creating a massive updraft of warm air. Updrafts can create unpredictable winds too, including deadly fire tornadoes. Yes, you heard that right: fire tornadoes. Fires can cause masses of air to rotate, forming a tornado. We’ve only observed this twice: once in Australia in 2003, and once in the Carr Fire in California in 2018. In the car fire that NATO had, winds clocking in at 140 miles per hour, not only did the tornado kill four people, it also spread the fire further. If that isn’t enough, remember that thunderstorms also come with lightning, and lightning can start new fires altogether. That makes for a lot of complex factors that contribute to fire spread, meaning predicting which way any fire is going to move is not easy.
Thankfully, there’s a whole field of science trying to tackle these issues from different perspectives. Researchers are figuring more things out every day, tracking fires from spark to finish and working directly with emergency teams to make sure they’re using the most updated data. They are making progress: updated models which take wind patterns into account have been able to map past fires accurately. That means that when we take the models and feed them the same conditions as historical fires, the simulations they produce line up with how the fires actually spread in reality.
It’s not that far of a stretch to go from that to predicting how future fires will develop. As these models grow to take into account more and more parameters, it won’t be long until they can be used in real-time in a wildfire situation - this could be life-saving.
We’re going to need these updated models now more than ever, even if we act aggressively to cut carbon emissions. We have to accept that even if we stopped burning fossil fuels today, climate change is already here, which means learning how to survive in a changed world with more frequent, more intense wildfires, and hopefully keeping more people safe.
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