Environment Canada has developed an algorithm, designated S3-1, to automate the derivation of 'snowfall' measurements. The algorithm was developed using data collected over two winter seasons from several test sites equipped with three SR50 Sonic Ranging Sensors (Campbell Scientific), and a Geonor Total Precipitation Gauge with a single alter-shield. The test sites were situated in different regions in order to develop an algorithm suitable over a range of snowfall climatologies.

The algorithm calculated a 'snowfall' statistic when the ensemble of three SR50 sensors showed an increase in 'snow-on-ground', and the Geonor indicated precipitation had occurred.

A review of the S3-1 algorithm is presented with verification statistics and case studies demonstrating the algorithm's performance in light, moderate, and heavy snowfalls, mixed precipitation, and drifting and blowing snow events.