Assuming a uniform snowpack, SWE can be thought of as the depth of water that would result if the snowpack was melted completely. The precipitation storage gauge measures precipitation in any form - rain, snow, sleet, etc. The precipitation is prevented from evaporating by a thin layer of oil on the surface of the stored liquid. As with the snow pillow measurement, a transducer in the shelter converts fluid pressure in a tube connected to the bottom of the precipitation gauge to an electrical signal. A shielded temperature sensor measures current air temperature, and the data acquisition system determines the minimum, maximum, and average temperature values on a daily basis.
Many sites also have an ultrasonic snow depth sensor .
The configuration of each site is tailored to the physical conditions, the climate, and the specific requirements of the data users. The sites are designed to operate unattended for 1 year in severe climates. Each site receives preventative maintenance and sensor adjustment annually. These readings are compared with telemetered data to check that values are consistent and compatible. Any values found to be beyond specified limits are carefully examined and edited to ensure a continuous, high-quality record.