We are having epic rain in California and that means epic snowfall in the Sierra Nevada Mountains. I wanted to make an interactive and current snowfall visualization to keep track of the amount of water being stored in the mountains. This is an average of snow water content for all of the 120 snow sensor locations in the Sierra. You can also look at specific regions (Northern, Central and Southern Sierras).

The blue/black lines on the graph (from top to bottom) represent the 100th(max), 90th, 75th, 50th (median), 25th, 10th and 0th (min) percentiles of snow water content for each date from 1970 to 2022. The red line is the current water years value.

In general, the snowpack water content to snow depth is about a 3 to 1 ratio so in the image, the average of 22" of snow water content amounts to about 66" (5ft 6inches or ~1.67 meters). It is much more (maybe 10 to 1) when the snow first falls, but over time it settles and also compacts from the overlying snow to get to this lower number.

Here is the interactive and updated daily (sometime in the west coast morning 8-10am) visualization.

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Sources and ToolsData is downloaded from the California Data Exchange Center website of the California Department of Water Resources using a python script. The data is processed in javascript and visualized here using HTML, CSS and javascript and the open source Plotly javascript graphing library.