Department of Civil and Environmental Engineering
University of Washington

Forests and Snow

Intermittent Snow and Process Dynamics

Snow Surface Temperature and Snow Depth in the Tuolumne Watershed

Orographic Precipitation


Mapping temperature in complex terrain

Spatial patterns of snow-fed streamflow

Rain vs. Snow

How meadow ecology relates to snow and climate

Intercomparison of Meteorological Forcing Data from Empirical and Mesoscale Model Sources

Silvicliture to maximize snow retention

Remote sensing of radiation to improve snow modeling

Wildflowers and Snow

Forests and Snow Storage in the PNW

Background: How Does the Forest Affect Snow Storage in the PNW?

By utilizing field observations collected by volunteer citizen scientists and students in central Idaho and a network of collaborating snow study sites, we are assessing forest effects on snow storage across the Pacific Northwest.

Trees intercept snow leading to less snow accumulation in forests (this is one of the reasons for tree wells, which backcountry skiers know well). Once the snow is on the ground, trees also provide shading from the sun and the wind (reducing melt), but the trees are also warmer than the sky which can increase melt (this is another reason for tree wells). Thus, the net effect of the forest on snowpack duration varies with climate, topography, and forest density.

Predicting Snow Duration

Previous investigations of snow duration in forests indicate that mean winter temperature is a key predictor of whether the presence of forest cover will accelerate or delay snow disappearance. However, local effects such as topographic position (e.g., north-facing vs. south-facing slopes), weather patterns (e.g., high winds), and forest characteristics (e.g., canopy density) also have an important influence on how the presence of or type of forest affects snow duration.

The Northwest Climate Science Center is supporting our work to develop a conceptual model for considering all of these local-scale influences, in order to help guide forest management decisions now, and under different climate warming scenarios. Understanding and predicting the effect of forest cover (and density) on snow duration is critical for land and water management decisions such as where to thin forests to minimize fire risk, where to supress fires, and how to respond to insect outbreaks.

To test and refine this model we need spatially distributed observations of where snow lasts longer in the forest and where snow lasts longer in the open. We have snow data from several field sites around the region thanks to collaborators at Oregon State University, University of Idaho, and Utah State University. However, we needed observations in more locations, so we ran a 4-year campaign to utilize citizen scientists.


The observational data compiled for this project are publicly available via the USGS ScienceBase archive.

Learn More

Read more about the conceptual model or check out our related publications. You can also read about our experiences with citizen scientists.

Watch a webinar describing PNW results and the resulting conceptual model framework that Susan presented in 2016.

Watch a talk from 2013 about the inception of this project that Susan presented at the PNW Climate Science Conference.

Contact Susan or Jessica to discuss further.

Material contained here and within the embedded links is based upon work supported by the Northwest Climate Science Center. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the funding agency.