Wet Snow Avalanche Research

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 Wet snow avalanches, including both wet slab and glide avalanches, are dangerous and can be particularly difficult to predict because they are relatively poorly understood compared to dry snow avalanches. They pose significant risk to human life and infrastructure in mountainous areas throughout the world.  Wet snow avalanches are caused by weakening in the strength of the snowpack, often triggered by rain, abundant sunshine, or warm temperatures. As temperatures increase and mid-winter rain events become more common due to a changing climate, wet snow avalanche frequency is expected to increase and the timing of this avalanche problem type will change. By analyzing the behavior of wet snow avalanches and the specific weather and climate factors that contribute to them, USGS scientists advance understanding of wet snow avalanches to better inform avalanche forecasting efforts, hazard mitigation, and land-use planning in avalanche terrain.

avalanche forecaster approaches debris of old avalanche

Wet snow avalanches are often triggered by climate driven rain events and can impact large areas with damaging results. (Credit: Eric Knoff, USGS/NPS. Public domain.)

Examining factors related to wet slab and glide avalanches

Both dry and wet snow avalanches constitute risk and ecological disturbance in mountainous regions throughout the world. However, wet snow avalanches are poorly understood. Wet slab avalanches depend upon the introduction of liquid water in the snowpack that changes the strength of a weak layer and decreases slope stability. The exact mechanism of wet snow avalanche release is still poorly understood. As such, scientists have studied some of the contributory meteorological factors influencing wet snow avalanche occurrence.

In Glacier National Park, Montana, USGS scientists work with the National Park Service on the Going-to-the-Sun Road Avalanche Forecasting Program. Here, scientists are able to collect valuable meteorological and snowpack data and apply the results of their studies directly to an avalanche forecasting program. The next step is to investigate the structural properties of the snowpack as water moves through in the spring during snowmelt periods and associated wet slab avalanche occurrence.

Avalanche debris on roadway

In avalanche prone regions around the world, wet snow avalanches create hazards and can significantly impact transportation corridors like this road in Glacier National Park, MT. (Credit: USGS. Public domain.)

Glide snow avalanches are dangerous, difficult to predict, and pose a hazard to spring opening operations along the Going-to-the-Sun Road each year. The difficulty associated with forecasting glide snow avalanches and the ineffectiveness of most explosive mitigation techniques render this type of avalanche a troublesome forecasting and management problem. Glide is the downhill movement of the entire snowpack along the interface with the ground. We investigated terrain factors associated with glide avalanche release and found that the smoothness of the underlying ground is an important driving factor. We have also used time lapse cameras to pinpoint the timing of glide avalanche occurrence and to examine the rate of glide crack change.

Climate-avalanche understanding improves safety

In avalanche prone regions, forecasting avalanches to reduce risk to life and property includes a complex analysis of weather forecasts, snowpack conditions, and topographic knowledge. Because wet snow avalanches are triggered by specific weather conditions combined with a particular snowpack structure, defining the most influential weather and snowpack factors can greatly enhance predictive models and forecasting efforts, thereby saving lives and property, and decreasing economic loss. As the climate becomes more variable, the importance of accurate forecasting based on changing meteorological influences will influence land management and development, hazard mediation, and ecological understanding.


Pair of images of Heaven's Peak with glide avalanche zones

Paired photos of Heaven's Peak showing glide avalanche released over the course of one hour. (Credit: USGS. Public domain.)

Additional Resources:

  • Going-to-the-Sun Road Avalanche Forecasting Program -  Glacier National Park has implemented an avalanche forecasting program to increase safety during the hazardous plowing season. On-site snowpack and start zone evaluations lead to enhanced avalanche forecasting and real-time snow safety.
  • Flathead Avalanche Center - Avalanche forecasts, field observations and education for Flathead National Forest, Kootenai National Forest, and Glacier National Park.