What is SNOTEL?
SNOTEL (Snow Telemetry) is an automated system of over 900 remote weather and snowpack monitoring stations managed by the Natural Resources Conservation Service (NRCS) of the United States Department of Agriculture (USDA).
Installed in high-elevation mountain basins across 13 western states and Alaska, SNOTEL stations operate autonomously year-round in harsh conditions to record precision snow data.
Key Acronyms on a SNOTEL Report
- SNWD (Snow Depth): Ultrasonic acoustic sensor pointing at the ground. It measures the height of the snow surface in inches.
- WTEQ (Snow Water Equivalent): Measured via a stainless steel or hypalon "snow pillow" filled with antifreeze fluid. As snow accumulates on the pillow, the pressure transducer converts the weight to equivalent inches of liquid water.
- PREC (Precipitation Accumulation): A storage precipitation gauge that catches both rain and melted snow over the water year starting October 1st.
- TOBS (Observed Temperature): Instantaneous air temperature reading in degrees Fahrenheit.
- TMAX / TMIN: Daily maximum and minimum temperatures recorded over the 24-hour cycle.
Recognizing Sensor Artifacts
Because SNOTEL stations operate without human attendance on remote peaks, sensors can occasionally produce false spikes:
- Ultrasonic Depth Bouncing: Heavy falling snow, blowing drift, or ice crusting can cause the acoustic depth sensor to jump 5-10 inches within an hour. Always cross-verify depth changes against WTEQ and adjacent stations.
- Pillow Bridging: In springtime freeze-thaw cycles, a rigid ice crust can bridge over the pressure pillow, causing WTEQ readings to temporarily flatline until the crust melts.