Montana Earth Science Picture of the Week

The dots on this map mark the locations of automated stations that measure how much snow has fallen. The system, called SNOTEL (for SNOwpack TELemetry) is operated by the Natural Resource and Conservation Service. SNOTEL instruments help scientists to know how much snow sits in these remote mountainous locations, so that they don't have to visit the areas to make measurements.

Important predictions . . .
The data obtained from the sites helps determine how much spring runoff to expect as the snow begins to melt. This is especially important in the management of reservoirs along Montana's rivers. For instance in April of 1996 Canyon Ferry Reservoir was lowered by over 15 feet because SNOTEL data indicated that there were unusually high amounts of snow present in the Upper Missouri Basin. Water from the reservoir was let through the dam in order to make room for the runoff that would certainly drain into Canyon Ferry as the snow began to melt rapidly in May and June.

A pillow sensitive to pressure . . . Although SNOTEL sites have several types of weather instruments, the most interesting is the "snow pillow" (see picture below). The pillow is made of various materials including steel, rubber, and a material called hypalon. It is filled with a solution of antifreeze (50/50 mix of water and ethanol). As snow accumulates on the pillow, it increases the pressure within the pillow. A fluid line runs from the pillow to the shelter where an electronic device determines and records the snow's water equivalent. Periodically radio waves transmit this and other data to climatologists.

Unique to the West . . .
The SNOTEL system is the biggest provider of real-time snowpack and high elevation climatic data in the world. It is only used in the western part of the U.S.A. where there are about 650 sites . . . Montana has 90.

Below: This photo, taken in Colorado, shows a SNOTEL site being prepared for the upcoming winter.

Photo courtesy of Institute of Arctic & Alpine Research
University of Colorado at Boulder

Terms: telemetry, reservoir