Researchers Will No Longer Be 'Snowed' In Predicting Future Avalanches

Montana State University professor of geography Kathy Hansen has received a $160,000 National Science Foundation (NSF) grant to do a comprehensive study of snow stability over space and time. Revealing some of the true properties and behaviors of snow could lead to better predictions of potential avalanches in the western United States as well as in the alpine regions of the world, she contends.

Karl Birkeland, an adjunct professor at Montana State and an avalanche scientist for the U.S. Forest Service National Avalanche Center, is co-principal investigator for the two-year study. He says that even in the East, where mountains are not as high but where concentration of recreational skiers is greater, the danger of avalanches is significant on all open snow covered slopes of 30 degrees and steeper when multiple layers of snow affect its stability.

That is the case this winter in the East, where many slopes have experienced numerous storms – making it heaven for skiers, but more risky on avalanche-susceptible mountainsides. Mt. Washington in New Hampshire, for example, accounted for the first two deaths of the current North American winter season when an avalanche buried two people last November.

"Snow is highly dynamic and we've done years of research on snow stability, but now we feel we have the tools to fill a fundamental gap of knowledge by studying how snow stability changes at various geographic locations over time, rather than just taking a single snapshot of an area and making generalizations," Hansen explains. "Snow changes quickly -- by the minute – and we want to understand better how to analyze characteristics of weakening that occur in snowpacks."

"As populations increase in and around mountainous regions, recreational activities are more concentrated. Hazards exist not only in terms of individual risks, but also to property, as more people choose to live in remote areas," says Tom Baerwald, NSF's Geography and Regional Science Program director in the Division of Behavioral and Cognitive Sciences. "This fundamental research by Hansen and her colleagues will give us valuable new information that will save lives in the future."

The Federal Emergency Management Agency (FEMA) has estimated there are more than 10,000 reported snow avalanches each year, but Birkeland, in his Forest Service role, estimates that the number of unreported avalanches, to include remote, inaccessible areas, could be up to a hundred times more numerous. He also says that over the past decade, the average number of deaths in the U.S. has nearly doubled due to avalanches. In 1991, FEMA estimated the annual death toll to be about 17. The death rate is now about 30 per year, according to Birkeland. Population increases in mountainous areas, and a general increase in skiing, snowboarding and snowmobiling in undeveloped backcountry areas are among the reasons for rising avalanche-caused deaths.

Much of the previous research on snow stability has looked at individual slopes at a single moment in time, but snowpacks, as researchers have discovered, are dynamic systems. Using a new snow stability test, and a sensitive instrument co-developed by Switzerland's Federal Institute for Snow and Avalanche Research and by the U.S. Army Cold Regions Engineering Lab, Hansen and Birkeland will sample, over limited periods, how snow stability changes over adjacent 900-square-meter plots across a variety of field sites. The researchers will collect data on how spatial patterns of snow change through time, looking at patterns of weak layer thickness, strength and microstructural change.

"In addition to our measurements with the SnowMicroPen, which will provide detailed microstructural information about the snowpack, we are also using a 'quantified loaded column test,' allowing us to measure the strength between layers of snow," Birkeland explains. "This is critical for avalanche prediction, because the large amounts of data we obtain should give us an indication of how a snowpack evolves and how avalanches release."

"Not only by looking at where a weak layer is, but how it changes day-to-day, will help us structurally and geographically in being more predictive," Hansen says. "We have figured out what precise measurements within the snowpack will produce the knowledge we need to assess the geography of snow strength and stability."

Beyond the basic knowledge the benefit of science, Hansen's group hopes to provide relevant insights in avalanche forecasting, protection of life and property, mitigation, and education for avalanche professionals, and for people who live, work, play and travel within mountain environments.