Front Range

Snowpack

Spencer Logan · May 21, 2010 · Front Range

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Weather

Strong sustained SW winds. Warm below treeline out of wind

Snowpack

We can split the snowpack into two elevation bands, above and below treeline, and the above treeline snow into two compass segments, northwest-north-northeast and east-south-west. Below treeline the snowpack is large, poorly bonded round grains wiht lots of dust mixed in. The snow has little strength. Fortunately, water is draining freely through it. It will stay in a steady state of weakness. You might be able to start a loose avalanche on steep slopes, if you push enough snow downhill.

There are several layers of white snow at the top of the snowpack on northwest-north-northeast aspects above treeline. They are recent storms, each topped by a melt-freeze crust. Then comes the distinct dust layer made up of large melt-freeze polycrystals. Just below the dust is a thin layer of small rounded grains, then some densely packed white windslabs. Under that, some older little-bit-dusty dusty snow. Lower layers are very slope dependent, a whole season of loading and faceting that is slowly making the transition to summer. The weak layers of concern are the recent melt-freeze crusts and around the distinct dust layer. With a cold snowpack in the morning, I was finding smooth breaks above and below the dust layer that took lots of force (CT25+ Q2). The breaks got easier and easier (CT10 Q2)as the snow warmed and softened.

On east-south-west aspects above treeline, there was little to no difference in the shallow layer of recent snow. Below the dust layer, the snowpack was mostly rounded grains. Areas with smaller rounds were stronger than areas with larger rounds. Again, test results on top of the dust got easier and easier as the snow warmed and softened.