The transition from manual to automated systems for acquiring snow data

Manually observed snow course data have been used extensively in streamflow forecasting in the Western United States for decades. Telemetry of snowpack data from unattended sensors began in the late 1960's. In 1977, the SCS began operation of its SNOTEL telemetry system. There are currently nearly 500 active sites in the system, each of which telemeters snow water equivalent, precipitation, and air temperature to a central computer. As a history of automated data accumulates, the transition from use of manually collected to automated data becomes possible. The SCS is currently in this transition period and plans to rely primarily on its SNOWTEL data in the future. The paper discusses the reasons for this transition and presents the criteria used to judge the adequacy of automated data sites as replacements for their manual equivalents. Expected results and impacts of the transition are also discussed.