Community Snow Observations

The CSO project models snow distribution on a daily time step and at spatial resolutions of 25-100 m. We assimilate in snow depth measurements from snow recreationists and snow professionals. And, we do this every single day, serving up daily grids of snow information right here. Scroll down to learn about our modeling process and how your measurements help! Finally, learn how to get involved...

Choose Your Domain

Building a model starts with picking your domain. How much area do you want to model? What resolution (think checkerboard square size) do you want? You need basic information (elevation and land cover) about your area to get started.

How's the Weather?

Our daily modeling process starts with acquiring gridded information on wind, precipitation, relative humidity, and other variables. We presently use the Climate Forecast System Version 2 which is available through 'three days ago.' In order to provide snow information all the way up to today, we use Global Forecast System data for the last three days of simulation. 

Run the Model Once

We use SnowModel to evolve the snowpack over the water year. SnowModel is a 'process-based' or 'energy-balance' model that charts the response of snow to solar radiation, wind, and other factors.

Get Community Snow Observations!

We next go fetch recent CSO submissions in our domain. We do some 'quality control' by comparing submissions from our participants to other sources of snow information. Unsual or 'outlier' points (orange) are removed from the modeling process.

Run the Model Again

The final step is that we run the model again, and we compare the modeled snow to the CSO observations. When we detect an error, we use that error (data assimilation) in order to help steer the model back on track. In this way, CSO participants directly improve our ability to model the snowpack.


We hope that you enjoy the ability to explore (zoom, pan, and so on) the distribution of snow in many of our high mountain areas. See what you can learn about how snow changes from one location to another, and also how it changes from one month to another. As we head into a new snow season, come back often to get the latest information on where it's white.