Colorado Wildfires Explained in One Chart

On Wednesday, more than a dozen wildfires were burning in Colorado, including massive conflagrations that are threatening two of the state's largest cities — Colorado Springs and Boulder. The fires are the result of a rare mix of ingredients: drought, unprecedented heat, lightning strikes from dry thunderstorms, as well as changing forestry practices and exurban sprawl that have helped prime forests for large fires. 

This one chart, more than any other graphic that I've yet come across, explains one of the main reasons why Colorado is so combustible right now. It shows snowpack data from a network of monitoring sites called SNOTEL, as measured in snow water equivalent. In other words, it shows how much water is (or was) present in the Colorado snowpack.

Chart of the Colorado snowpack during the past four years, showing the thin snowpack and early melt in 2011-12. Click on the image for a larger version. Credit: Natural Resources Conservation Service. 

The lines trace the buildup and melt of the Rocky Mountain State's snowpack during the past four years, and they clearly show that the 2012 winter season delivered anemic snow cover to Colorado. Not only that, but the snow that did fall melted extremely early, allowing soils to dry. Studies have shown that years with early snowmelt tend to have more severe wildfire seasons. This contrasts with the 2010-2011 winter season, which featured plentiful snowfall that lasted into early July. 


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According to the chart, produced by the Natural Resources Conservation Service, the 2011-12 winter snowpack peaked on March 6, 2012, more than a month earlier than average, and the meltout date of June 4 came well before the median meltout date, which is June 25. And at its peak, the snow cover contained much less water than normal.

The back-to-back combination of the deep snowpack in 2010-11, which encouraged spring plant growth, and the lack of snow this past winter has led to abundant brush that has dried and ready to burn.

As the snowpack began melting in March, veteran environmental journalist Tom Yulsman wrote : “Like a spring avalanche, snowpack in Colorado has plunged off a precipice.” Yulsman, quoting officials, warned of severe drought conditions to come, along with a potentially fierce wildfire season.

Unfortunately, that is now playing out.