Front Range

Avalanche

Mike Bannister · Jan 13, 2018 · Front Range

Weather

Sunny turning to snow

Avalanche

We snow no indications of instability other than the slide and pits. No obvious collapsing or whumpfing. I was finishing my pitch and made a hard traverse behind a tree and stopped. After stopping, the snow started moving with the crown at my skis. NE aspect @ 11K feet. Slide was 40' wide, ran 20', with a 3' crown. Bed surface was the snow/depth hoar interface. Top of the depth hoar felt icy with possible surface hoar. My traversing ski track basically acted as the crown with some (7') of propagation on both sides. Slope at the crown was about 30 degrees with a convexity below. I dug a pit and isolated 3 columns in the crown. All three failed on isolation, no taps. Consensus was that other bulges in the area would likely move. We didn't test them. After the slide we traveled approx 200' east and dug another pit on a similar aspect and slope, but in a more protected location. From top down: 14" of soft (fist) snow, a 1/4" icy layer, 12" of 4 finger snow, and then 8" of depth hoar. Columns consistently failed at 7 or 8 taps from the wrist on the icy layer, and then at the depth hoar at 12 taps total (10 wrist, 2 elbow).