6.1.2 Snow courses
Onsite measurements, known as snow courses, are an essential part of determining avalanche conditions—both current and past as well as those that may occur in the future. Onsite measurements are taken at fixed sites on both flat and sloped surfaces at regular intervals throughout the cold season. They are also taken at particular sites to address specific needs, such as the likelihood of avalanche formation. In these cases, a partial or full profile of the snowpack is assessed.
In the United States, there are two types of onsite measurements: manual techniques and routine, automated, in-situ measurements called SNOTELs. SNOTEL stands for snowpack telemetry. As of 2009, there were more than 1,200 manually-measured snow courses and over 750 SNOTEL sites in the western U.S. states, including Alaska.
Before starting the discussion of onsite measurements, it is strongly recommended that you review two chapters of the American Avalanche Association's "Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States" guide.
- "Snowpack Observations” at http://www.avalanche.org/~research/guidelines/pdf/Chapter2.pdf. Please refer to it as you read through the module's descriptions of snowpack assessment techniques since it provides more detailed information than can be included here. The chapter can also be downloaded and used as a guide in the field.
- "Manual Snow and Weather Observations,” provides background information on snow and weather observations. http://www.avalanche.org/~research/guidelines/pdf/Chapter1.pdf