Standard SNOTEL site with: Single snow pillow | Dual pillows
Enhanced SNOTEL site with: Enhanced climate sensors | Soil sensors
The most common type of SNOTEL site in Idaho is shown below. The site makes use of: one snow pillow to measure the snow water content of the snowpack, a storage precipitation gauge that measures total precipitation (snow, rain, hail) year round at the site. and an air temperature sensor that records hourly air temperature, as well as daily maximum, minimum and average values. Many, but not all, SNOTEL sites have a snow depth sensor to record the depth of snow on the snow pillow. SNOTEL sites are powered by the sun using solar panels. Data are collected and stored by a datalogger, located inside the shelter, and then transmitted by radio via meteor burst communication to a master station where the information is made available to the public. Ground truth poles mark the location of manual wintertime snow measurements that are used to verify snow pillow measurements.
A number of SNOTEL sites are equipped with dual snow pillows as the site shown below. The second pillow offers a level of redundancy should the primary snow pillow be damaged by tree fall, animals, or human vandalism. Sites that have dual pillows are often either difficult to access during the winter making repair unlikely and/or provide critical snow water measurements that water supply forecasts depends on.
A growing number of SNOTEL sites include a combination of enhanced climate sensors (pointed out in yellow in the photo below). These enhanced sites may include sensors to measure any or all of following: wind speed/direction, solar radiation, relative humidity, precipitation (tipping bucket rain gage - not shown), or barometric pressure (not shown). Enhanced sites generally also include the soil moisture and soil temperature sensors shown in the next section.
Use this clickable map to differentiate enhanced sites from standard sites; blue dots link to enhanced SNOTEL sites while red dots link to standard ones.
Soil moisture and soil temperature are measured at enhanced SNOTEL sites using Hydra Probe sensors, like the one shown below.
Photos below shows the standard depths for placement of soil moisture / soil temperature sensors at 2, 8, and 20 inches from the top of the mineral soil, i.e. under the organic/duff layer. Once sensors are inserted into the undisturbed soil profile the holes used during installation are backfilled. The following photo shows a completed installation where orange rebar caps mark the location of the sensor transect (dotted white line).