Slower snowmelt in a warmer world

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In regions where snow is an important component of the annual water budget, it is vital for water and land managers to understand potential climate change impacts on snow water resources and reliant human and ecological systems. There is general consensus that projected warming will cause earlier snowmelt, but how snowmelt rates will respond is both poorly known and a critical determinant of future streamflow.

In a project conducted at the National Center for Atmospheric Research, historical observations and climate model simulations are used to develop and test a hypothesis that snowmelt will be slower in a warmer world. The results are reported in the journal Nature Climate Change

Seasonal and inter-annual snow accumulation and melt patterns 

Accurate seasonal runoff predictions in mountainous regions require a process-based representation of how snow accumulation (e.g. precipitation, wind redistribution) and ablation (e.g. melt, sublimation) vary in time and space over complex terrain. A project in the southern Sierra Nevada of California evaluates when and where meltwater is available to the soil and river systems and how these processes vary with seasonal meteorology, land cover, elevation, and climate conditions.

How does forest cover influence our water resources?

Using a process-level approach that relies upon observation and models, my work examines how forest cover alters the surface energy and mass balance. Ongoing research projects serve to build a holistic understanding of the net effect of forests and forest management on basin water yield and seasonal runoff timing - and how these processes are linked to climate, latitude and landscape properties. 

Research topics

Future changes in rain-on-snow flood risk

Photo by Lars Peterson

Rain-on-snow flood event, Kirkwood, California
My research interests and experiences are on the topics of terrestrial hydrology, hydrometeorology, and remote sensing in mountainous and forested seasonally snow-covered environments.

I evaluate the availability of freshwater in these environments and the physical mechanisms and pathways responsible for its evolution.

Uncertainty of windflow prediction methods in mountain hydrology 

In alpine regions, wind plays an important role in determining snow redistribution (drift and scour) patterns, which influence the duration and spatial patterns of spring and summer meltwater availability in headwater basins. An ongoing project in the Canadian Rockies evaluates the hydrological uncertainty associated with windflow representation methods commonly used in snow models.


Source: Kirkwood Ski Resort

Photo by Angus Duncan

  -  Water resources

  -  Hydrology

​  -  Forest hydrology 

  -  Hydrometeorology

  -  Snowmelt modeling

  -  Climate change

  -  Remote sensing of surface processes

  -  Ground-based measurements

  -  Forest radiation models

  -  Snow - forest interactions

  -  Micrometeorology

​  -  Data visualization


Large and costly flood events can occur when warm storm systems deposit heavy rainfall on snow-cover, especially in mountainous areas.  Flood forecasters and reservoir operators lack guidance on how this flood risk will respond to climate change at the scale of mountain river basins. In a recent study, we assessed future changes in rain-on-snow flood risk over western North America. We find the associated flood risk will shift to historically colder regions with flood volumes more than doubling in some regions of the Sierra Nevada and the Rocky Mountains. The results are reported in a new paper in the journal Nature Climate Change.   Read-only version (free):