Rain-on-Snow Event Hydrology and Climate Impacts

Rain-on-snow events occur when liquid precipitation falls onto an existing snowpack, triggering rapid melt and often leading to accelerated runoff and flood hazards downstream. These events are governed by the interplay of atmospheric drivers, snowpack thermal and hydrological properties, and catchment characteristics. Key factors include the intensity and duration of rainfall, snowpack density and stratigraphy, antecedent snow water equivalent and ground conditions, and topography. Under warmer climates, the frequency and magnitude of rain-on-snow events are projected to increase, reflecting shifts in precipitation phase and enhanced moisture transport. As a result, river basins in mid-latitude and high-elevation regions face heightened flood risk, with implications for water resource management, infrastructure resilience and ecosystem health. Advances in observation, process modelling and causal inference have improved understanding of how large-scale climate variability and local snowpack dynamics interact to modulate event occurrence and impacts. Practical applications range from improved forecasting systems and early warning to adaptive reservoir operations and landscape planning that anticipate changes in seasonal water availability and extreme runoff.

Research from Nature Portfolio

Recent studies have developed refined methods to identify rain-on-snow events and explore their climatic drivers across North America. By integrating hydrometeorological observations with advanced causal inference techniques, researchers have demonstrated a strong causal linkage between variations in North Pacific sea-level pressure and regional rain-on-snow frequency. This work has revealed how shifts in large-scale circulation patterns influence both rainfall occurrence over snowpacks and subsequent snowmelt dynamics. The insights offer a pathway to improve predictive models of flood-generating events by incorporating sea-level pressure indices alongside conventional meteorological indicators.

Rain-on-Snow Event Hydrology and Climate Impacts publication trend

The graph below shows the total number of articles in rain-on-snow event hydrology and climate impacts across all publications each year (not limited to Nature Index journals).

Technical terms

Rain-on-Snow event: Occurrence of rainfall falling on an existing snowpack, often triggering rapid melt and potential flooding.

Snow Water Equivalent (SWE): Depth of water contained within a snowpack if fully melted, a key measure of snowpack water storage.

North Pacific Index: Climate index based on sea-level pressure variations over the Northern Pacific, influencing atmospheric circulation and rain-on-snow frequency.

Atmospheric River: Narrow corridor of enhanced moisture transport in the atmosphere that can deliver intense precipitation to coastal and mountainous regions.

References

1. Northern Pacific sea-level pressure controls rain-on-snow in North America. Communications Earth & Environment (2024).
2. Rain-on-snow events over North America based on two Canadian regional climate models. Climate Dynamics (2017).
3. Large-scale analysis of changing frequencies of rain-on-snow events with flood-generation potential. Hydrology and Earth System Sciences (2014).
4. Human influence on the 2021 British Columbia floods. Weather and Climate Extremes (2022).