A Conversation with Snow Scientist, Megan Guinn

By Erin Hassett, Ph.D. student at the SUNY College of Environmental Science and Forestry (ESF) in Syracuse, NY.
All photos provided by Megan Guinn with permission for use.

Introducing Megan Guinn, Snow Scientist

Snow Scientist, Megan Guinn, smiling in the snow
Megan Guinn digging a snow pit and looking at snow crystals through a loupe.
Sunburst Mountain on Turnagain Pass AK, 2023.

Nestled between the jagged mountain peaks in Grand Teton National Park, Wyoming sits Middle Teton Glacier, one of the largest and most tourist-attracting glaciers in the park. A snow scientist, Megan Guinn, travels to this glacier every few weeks to measure its decline since warming temperatures are increasingly melting this prominent feature.

This work is tough because these areas are remote, challenging to reach, difficult to walk on, and generally dangerous, but Megan is concerned about climate change’s effects on our snow and water resources.

After first arriving to the glacier in the springtime, Megan installs ablation stakes– long poles that are drilled into the ice using a steam-powered drill. As the ice melts over the year, more of the stakes become exposed, allowing Megan to track the speed and amount of recession.

This information is important to obtain because glaciers provide essential benefits to both humans and the surrounding ecosystem, and Megan worries that these benefits would be lost if the glacier disappears.

“Glaciers have a strong influence on some Alpine watersheds since they provide water during the dry months when aquifers might dry up in other basins,” Megan explained to me. “They also provide habitat for key high-Alpine aquatic species. Their geomorphic processes allow them to carve out rock, and they provide a pretty substantial mineral base to watersheds. The snow and ice also help with reflecting and refracting incoming solar radiation.”

Unfortunately, as the climate warms, more ice is lost, creating a positive feedback loop: as the ice continues to melt, there is less ice to reflect sunlight, and this leads to more ice melting. Not only will species that rely on glacier habitat be lost, but millions of people living downstream will have dwindling water resources during the dry season.

Snow Scientist, Megan Guinn, digging through snow
Megan conducting a hand hardness test on a snow pit to identify inconstancies of the snowpack layering.
Turnagain Pass, AK, Winter 2023.

On the Path to Snow Science

I have known Megan for a few years now, mostly as an avid skier, bikepacker, and hiker. It was she who had introduced me to the concept of snow science, and passing photos of her on snowy mountain peaks and glaciers piqued my interest. I wanted to learn more, and she agreed to meeting with me for an interview to discuss her trajectory into snow, glacier, and avalanche research.

I learned quickly that Megan’s interest in snow science started during her childhood when she grew up skiing in Colorado.

“I remember skiing always being near and dear to my heart,” Megan explained to me. “I’ve always had this urge to be in the snowy mountains. I applied to school at Montana State University mostly because the front of the pamphlet had a skier on it, and I thought that was so cool– that’swhy I want to go to that school.”

She knew that she wanted a career that allowed her to be outside, and, at the time, environmental engineering with a focus on water resources was her ticket to do that. It was during her junior year when she took a graduate-level snow mechanics class that her interest in snow research grew.

“It was probably the hardest class I’ve ever taken but also the most interesting,” she said. “I was amazed by the inner working of snow, snow metamorphism, the snowpack energy balance, and how it’s all dependent on energy.”

It was then that she realized that snow research was something that she could do for her career. So, she applied to and was accepted into a program at Portland State University, Oregon where she would study the influence of forest fire effects on snow hydrology.

Snow Scientist, Megan Guinn, walking through heavy snow
Megan cutting out a block of snow with her pole to understand the spatial variability of overall snow surface conditions following a storm. This helps avalanche forecasters identify where snow stability problems may exist. Prodding at the snow and conducting a hand test over the span of a ski tour can help alert to the changing snowpack.

Forest Fires and the Future of Water

Snow is an important substance on Earth because of its exceptionally powerful reflective ability, known as albedo. When snow encounters sunlight, it reflects almost 100% of that back into the atmosphere, so it’s an important driver in reflecting global heating.

“When a forest burns, it litters the snow surface with black carbon,” Megan explained. “When the snow is melting, the black carbon concentrates. This decreases the snow’s albedo. When the snow is darkened, it absorbs a lot of that heat, which melts the snow faster, so you get an earlier snow disappearance date and other factors that go along with it.”

Megan Guinn setting up tripod
Megan taking a hemisphere photo of the overhead canopy at one of her field sites. These photos are used to get canopy density measurements and are used to identify the variables that are influencing snow accumulation and melt in burned forests.
Lionshead Burn area outside of Detroit, Oregon. May 2022.

This is concerning because the extent of acres burned by forest fires is increasing in the United States, especially in the western U.S. where Megan’s work was focused. With fires burning more forest area, this can have a greater negative effect on the snowpack–continual layers of snow buildup on the ground which do not melt for months.

Like glaciers, snowpack is essential for humans when it melts since it slowly releases water for communities that live downstream; however, the timing of melt and the speed at which the snow melts have become unpredictable.

“There’s a pretty significant influence that the snowpack has on a forest,” Megan described. “The snow keeps the forest moister over the drier months of summer, but if there’s a forest fire or some kind of disturbance event that causes a loss of snowpack earlier, then we have a longer period of that dry spell that then works as a positive feedback loop, building up the amount of dry forest.”

And this buildup of dry forest makes the forests increasingly more susceptible to forest fires. Megan specifically studied in the Pacific Northwest, and that region is experiencing the largest proportional increase in forest fires out of anywhere in the U.S.

This is also worrying since up to 75% of water used in some western states comes from snowmelt, according to the USGS. If the amount and rate of snowmelt changes, this affects our ability to collect and use water.

“You can look up reports on the Colorado River basin in the last couple of years and see how dire that situation is,” Megan said. “When you look at the snow survey reports that the NRCS (Natural Resources Conservation Service) puts out, the amount of snow falling has not really changed. We are having normal to above average snow years as far as peak snow goes, but when the snow starts to melt, it is melting in erratic and unpredictable ways.”

Megan Guinn setting up a mountaintop weather station
Megan fixing the Sunburst Weather station on Turnagain Pass AK. These stations provide consistent measurements of wind speed and direction as well as temperature, and some even provide snow depth and snow water equivalent. These measurements help inform snow scientists of current and previous conditions.

One reason for this melting irregularity is the increasing amount of rain falling on snow.

“These rain-on-snow events can warm up snowpack really fast, melt a large portion of it, and cause huge amounts of flooding,” Megan elaborated. “This makes it challenging for water resource managers to close the reservoir spillways early enough to retain that snowmelt because, if there is a rain-on-snow event, it wouldn’t take long for the pulse of water to get down to those spillways and cause serious damage to civilizations. It’s really unpredictable.”

And flash flooding from snowmelt is an increasing problem seen across the U.S. every year, leading to intense property damage and death.

Megan Guinn working in a snow-laden forest
Megan weighing a federal sampler that has just been plunged in the snow. The weight of the snow in the tube can be converted to a Snow Water Equivalent (SWE) metric, and it is the most accurate way to measure the water content of snow to date.
Lionshead Burn area, Detroit Oregon, March 2022.

The Growth of Erratic Avalanches

After Megan completed her master’s degree at Portland State University, she spent time at the Chugach Avalanche Center in southern Alaska. As a passionate skier and water resource/snow scientist, she naturally became invested in avalanche research and forecasting.

Like snowmelt, the frequency of avalanches is also changing, and one reason for this is the shifting layering of snow. When snowfall and temperatures are consistent, the snow stacks in even, homogeneous layers. However, avalanches form when snow begins to stack in different layers, with some layers soft and loose while others are dense and hard. When a portion of snow breaks away, this snow is called a slab, and when this triggers more snow to tumble, it “propagates” into an avalanche.

“With climate change, avalanches are becoming less predictable,” Megan reiterated. “What’s been happening in recent years is that the snowpack in maritime climates is starting to get more inconsistencies.” And this is leading to the formation of different types of avalanches which has unknown consequences for avalanche forecasting.

Megan explained that there are eight different causes of avalanches, three of which are related to slab formation: Persistent Slab, Wet Slab, and Deep Persistent Slab avalanches. Persistent Slab avalanches form when snow piles on top of a weak layer, and eventually, that weak layer breaks. Over time, Persistent Slabs can form into Deep Persistent Slab avalanches with many more layers of snow. This type of avalanche can last for months.

“These kinds of avalanches are usually the deadliest, most unpredictable… Persistent slabs have not happened at the rate that they’re happening now,” Megan said.

According to the Federal Emergency Management Agency’s risk index map, risks of avalanches are greatest in the western U.S. in states like Colorado, Wyoming, Utah, Washington, and Alaska, amounting to millions of dollars of expected annual losses and dozens of deaths every year. It is unclear if the rising avalanche inconsistencies from climate change will lead to more deaths, and Megan hopes to be involved with addressing these uncertainties.

For Megan, avalanche forecasting is necessary for determining risk of occurrence and potentially saving lives; however, it is a challenging skill that involves many interacting, dynamic environmental factors, such as the angle of the terrain (most avalanches occur on 30–35-degree slopes), the type of snow crystals that have formed, how the snow has layered, and the strength of each of the layers.

Megan Guinn happy and playing with snow
Megan showing the formation of surface hoar after snow machining around Seattle Ridge.
Turnagain Pass, AK.

“It can get very complicated very fast,” she confirmed. “Temperature gradients within the snowpack itself and between storm events can drive different snow metamorphism [such as varying types of snow crystals] within the snowpack …You might dig in one piece of terrain but then walk five feet and have a totally separate type of snowpack. You might have a different aspect, no sun, or it might be blocked by trees.”

Forecasters like Megan perform many types of tests to assess the stability of the snowpack. One way to do this is by digging a deep snow pit to observe the layers of snow, determining if there are any inconsistencies. Then, among other tests, you can perform a “hand hardness test”. Megan demonstrates with her pointer finger, gently pushing in her nose.

“You apply pressure to the snowpack with the same amount of pressure you would when pushing in your nose, and you start with your fist. So, if you can apply that amount of [fist] pressure and go through the snowpack, then that has ‘fist hardness’. That’s not a very hard snowpack. Then, you can do a four-finger test, a one finger test, a pencil, and then a knife.”

Megan Guinn and a flat wall of solid whie snow
Megan analyzing a buried weak layer in a snow pit on Turnagain Pass AK.

Performing this hand hardness test allows Megan to construct and visualize a hardness profile over the snowpack to determine which areas may have potential weak layers that could break away from the denser/harder snow layers, forming an avalanche.

“It’s complicated, and avalanche forecasters are very good at what they do. They are extremely smart people and must think on a broad scale then communicate to all audiences that have less knowledge.”

Next Steps

Currently, Megan started a new position with the Airborne Snow Observatories, using LiDAR to map seasonal snowpack in the western U.S. This information will allow state agencies to better predict snowpack quantity and model future snow melt. She is additionally working part-time in Bellingham, WA as an intern observer with the Northwest Avalanche Center (NWAC). Here, she is primarily working in the western North Cascades and will teach Avalanche Awareness courses to her local community through NWAC and other private guiding companies.

“Avalanche forecasting is climate dependent, it’s intuitive, and it’s very challenging,” Megan concludes. “I think the beautiful thing about it is that it’s not just a technical mind that’s needed–it takes intuition of snow and snowpack and knowing how a snowpack develops which I believe can only be learned by being out in the field and in the snow, which is the best part of the job.”

Megan Guinn in a convention centre with a board displaying information on "Forest fires may increase snow retention"
Megan presenting her research on the influence of forest fires on snow hydrology at the American Geophysical Union conference.
New Orleans 2021.

About the Author

Erin Hassett is a Ph.D. student at the SUNY College of Environmental Science and Forestry (ESF) in Syracuse, NY where she researches greenhouse gas cycling in wetlands. She is an editor for Unearthed, the campus literary magazine, and she maintains a blog on environmental topics and outdoor recreation, called The Footprint. When not writing, you can find her on two wheels or a mountaintop.

Email:
Hassett.erin@gmail.com
IG: @erinmhassett
Twitter: @ecoErin_


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