Montana News
How does winter snowpack affect summer wildfires?
(upbeat music) - Welcome to The Big Why, a series from Montana Public Radio where we find out what we can discover together. I'm your host, Austin Amastoy. This is a show about listener-powered reporting. We'll answer questions large or small about anything under the big sky. By Montana's, for Montana, this is The Big Why. This week, we've got the perfect question to ponder as we sizzle under that scorching July sun, and joining us to explain is reporter Victoria Trachler, hi, Victoria. - Hey, Austin, great to be back. Today, we have a great listener question from Valerie Kirth in Helena that I think touches on the inner armchair meteorologist in all of us. Here's Valerie. - Is winter snowpack really correlated to summer wildfires or is it more complicated than that? - Oh, I remember all the skiers complaining last winter about snowpack, and now that the fire season's here, I have to say, Victoria, I'm getting a little nervous. So how are we gonna break this down? - I think we need to start by addressing what is snowpack exactly. What I learned is that snowpack is like a big mountain reservoir that we have in the arid mountain west. It's the snow that accumulates between the fall and the following spring, building up a reserve of frozen water that melts throughout the summer. - In Montana, it contributes about 80% of our water supply. How and when it melts off impacts our wildfire seasons. Dan Borsam is an expert in this. - I'm a predictive services meteorologist for the Northern Rockies Coordination Center. - That's an interagency group focused on coordinating fire response resources and keeping people informed during fire season. - So it seems that our window to have a fire season is often dictated by how fast our spring storm patterns shut off. The bottom line there is snowpack is important, but it also may be overridden by something that occurs later in the spring. - Hmm, what's he talking about there? - He means late spring storms could add valuable moisture even after a dismal snow year. Dan says he sees snowpack as one component in the long-term aspects of predicting fires, but there are a lot of other factors too. Temperature, weather patterns like El Nino and La Nina and the history of weather in a region. - Well, all those factors taken into consideration, why is it that we worry so much about our wildfire seasons then when we have a low snowpack year like this one? - So it's definitely an important component for two main reasons. First, Dan says less snowpack means less groundwater, which may dry out plants and trees making them more susceptible to fire. This can also be worse during times of drought. And second, how long the snowpack sticks around can affect whether fire creeps up into high elevation areas? Because if spring temperatures are high and that snow melts quickly, those alpine areas are left bare early in the year. - And that could add to, I would say, a difficulty, severity is one word, but I think difficulty because if we're dealing with high elevation fires, they're not as easy to put out. They may last longer on the landscape. - While snowpack certainly matters, so much of what happens during fire season depends on what happens both before and after the snowfalls. A low snowpack year a couple of seasons ago could contribute to ongoing drought, for example. And even after a snowy winter, high summer temps and low precipitation could equate to conditions ripe for an abnormally fiery summer. - So those conditions may create an abnormally hot, fiery summer, but what exactly is normal when we're talking about wildfire seasons in Montana anyway? So Dan actually brought this up to me. - When I say normal a given year, we're looking at somewhere around 175 to 200,000 acres burning. So normal fire season just means that our resources are trained up and ready to go and they're gonna be fairly busy. - Okay, so let me see if I've got this all right. Snowpack is an important factor when predicting a wildfire season, but there are loads of other moving pieces too, like temperature, drought, and weather factors. - Yep, exactly. So to answer Valerie's question, while it's not quite as simple as less snow equals more fire, snowpack does have an influence on our fire season. - So with all of this in mind, Victoria, what does the future of Montana's snowpack look like? - Yeah, I had the same question. So I met up with Assistant State Climatologist for the Montana Climate Office, Zach Hoyleman. - It's a hard thing to predict. - Oh, I would personally expect to see less snow accumulation over time into the future with a shortened window of the snow accumulation season. - That does not sound like it bodes well for future fire seasons. - Again, it's hard to say for certain because Montana has such a diverse landscape with sprawling plains and big mountains, but a shorter snow window can create more chances for fire. But Zach said that overall precipitation, where and when that happens is really key to all of this. - And that's really where the rubber meets the road in terms of wildfires. - So when we talk about precipitation, are we only talking about snow or does rain play a part in this as well? - Rain does play a role, and it's a bit of a double-edged sword. On the one hand, good spring rains can help offset the impacts from a bad snow year if it keeps things wet and cool. But on the other hand, it can sometimes exacerbate fire conditions. High elevation rain can increase snow melt and flush a big part of our water supply for later, leaving us drier later in the summer come fire season. And while the rain helps plants grow, if those plants then quickly dry out, that's just more fuel to burn. And in fact, to make things more interesting, wildfires can actually impact snowpack. - Wait, how does that work? - Fresh white powdery snow doesn't absorb as much heat as say dirty old snow you see on the sidewalk in February. And what researchers have found is that wildfires are creeping higher and higher into snowpack zones. The leftover carbon and soot reflects less sunlight. And when less sunlight is reflected, it means more of that energy is absorbed into our atmosphere, contributing to warming conditions, thus diminishing snowpack. - Ah, you know, it kind of reminds me of wearing a black shirt on a sunny day. It really feels like you're soaking up all those rays and more heat. - Exactly, it's just like that. And University of Nevada professor Anne Nolan and her students have focused on this topic for years. Here's Anne. - 10 to even 15 years after a fire, we see this earlier melt out because of two things. One is because the canopy's burned off. And the second is because the standing charred trees shed flat carbon onto the snowpack. So it's really a cycle of cause and effect in these higher elevation regions. - That's right. But while we've been talking a lot about wildfires and are concerned that these factors might worsen them, Anne brought up an important thought to keep in mind during fire seasons. - Fire's a good thing. It provides opportunities for biodiversity, for new trees, it opens things up. It's just that the fires of late have become a lot more severe and big and hard to manage. And it puts people in infrastructure in danger. - You know, Victoria, one more question, this has me pondering. We're recording this in mid-July. Some wildfires are starting to pop up in parts of the state. Did any experts you talked with have anything to say about what's ahead for this fire season? - Yeah, so Dan thinks that this year is likely to be relatively close to what he calls normal in much of the state. But with fire, as we've learned, there are so many unknowns. So we'll have to wait and see. (dramatic music) - And listeners can always check in with our news team's fire coverage as the season gets into full swing for the latest. Victoria, thank you for coming on and sharing and reporting with us. It's good to have you back. Thanks so much for having me. Now we want to know what makes you curious about Montana. This show is all about answering your questions. So send them to us at bigy.org. 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