Trends and variability in rain-on-snow events

We analyzed rain-on-snow (ROS) events in two reanalysis products. ROS events are a relatively rare phenomenon outside of a few regional maxima including western Eurasia, the higher elevations of western North America, the northeastern United States, and southeastern Canada. ROS events occur at the high latitudes, especially away from the continental interior, and no robust trends were found in the frequency of ROS events. We also explored the variability of ROS events with dominant large climate modes. The most robust relationship was found with the Arctic Oscillation or North Atlantic Oscillation (AO/NAO). The most notable variability associated with the AO/NAO was a northeast/southwest dipole feature across western Eurasia. More ROS events were found for northeastern Europe for the positive phase of the AO/NAO due to the increased frequency of rainfall. However, more ROS events were found for Central Europe for the negative phase of the AO/NAO due to the increased frequency of snow cover.