Rain-on-snow events in Switzerland: recent observations and projections for the 21st century

Abstract

We analyze the temporal and spatial patterns of rain-on-snow (ROS) events during the last 4 decades in Switzerland and project the future occurrence of ROS events based on atmospheric warming under the A1B greenhouse gas emissions scenario. The results indicate that ROS events occur mainly during winter months at low elevations, and during summer months at high elevations. The solid/liquid precipitation ratio and the duration of the snowpack explain the spatio-temporal characteristics of ROS events. Observations indicate a trend towards a slight reduction in ROS events during the study period (1972−2012) due to decreasing rainfall, and a reduction in snowpack duration due to warming temperatures. However, increased warming may increase the frequency of ROS events in future decades, especially at high elevations (>2000 m) where the snowpack will still be present during most of the year, but liquid precipitation will become more frequent.