Logs of weather history (showing daily precipitation, high and low temperatures, and snowpack depth) are generally available for many back country locations. But few people know how to extrapolate from weather history to a hypothetical snowpack profile. Developing an ability to predict conditions in a snowpack based on a knowledge of weather history and concepts of snow science is fundamental to understanding avalanches.

This presentation demonstrates a classroom exercise for instructors in avalanche safety courses. This exercise helps students become aware of the forces at work on snow and how these forces produce conditions a snowpack. Participants examine an archive chart of weather history from an earlier year. Taking one a line at a time, they identify the significant weather events and determine how these events would affect the depth of the snowpack, create or obliterate a layer, or change the characteristics of a layer.

Then participants predict the layers and types of snow they would find in the snowpack, draw a profile that depicts their predictions, and check out their predictions by comparing them with actual field data (also collected the earlier year).

This exercise can be adapted for students at any level. In avalanche safety courses, it can be expanded to include a field trip to dig a snow pit and examine its characteristics.