Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I went to confirm the persistent slab problem from an area where we had reports of collapsing and shooting cracks on December 11th.

• The persistent weak layer is still collapsing and the cracks are still shooting, 4 days after the storm. These were localized and largely the result of brush under the snowpack until about 8500 feet when large areas began to whumpf around me and cracks shot up to 50 feet away from my feet.
• I dug down after getting a big collapse and got repeatable snowpack test results that confirmed the instability. The concerning structure consists of depth hoar under a consolidating slab. (See snow profile)
• I found large (2 cm) surface hoar from the trailhead at 7000 feet up to 8400 feet, where it got much smaller and spotty. The top few inches of snow under the surface are faceting.
• I saw debris from a large avalanche on McGee that probably ran on the 11th during the height of the storm.
• It was mostly clear and winds were calm. A beautiful day in the mountains. Temps stayed below freezing on shaded northerly slopes, though it was warm at lower elevations when I got back to the car around 12:30 pm.

I skied with my inclinometer in my pocket and even took it out to check the angle before crossing a few slopes. With all the red flags on Red Moutain, I think it was well worth the effort to avoid triggering an avalanche.