13-14

The avalanche under Chimney Rock (north of Cooke City) was triggered by a sledder on Saturday, March 16. He was caught, pulled his airbag and not buried. This slope had hundreds of track on it throughout the winter.  Tracks do not indicate stability, especially when we are dealing with a deep slab avalanche problem. The untracked face of Crown Butte has a similar snowpack structure and would be a dangerous choice to play on. Photo: GNFAC

The crown was 3-4 feet deep.  The avalance was triggered aproximately 50 feet below the crown on a rock band.  Facets that formed in the early season fractured and propagated across the slope. Photo: GNFAC

Two snowmobilers triggered the south face of Abundance north of Cooke City on Saturday, March 16.  It was a deep slab avalanche that broke 3-4 feet deep and injured and partially buried one rider. Photo: GNFAC

A group of seven snowmobilers was riding north of Cooke City when one was caught in an avalanche on a steep, northwest facing slope on Crown Butte. He was fully buried and located about 1.5 hours later 6 feet deep. The avalanche broke 700 feet wide and 2-5 feet deep on depth hoar crystals about 1 foot above the ground. The avalanche ran 800 feet vertical and 1600 feet slope distance. Debris ranged from 5 to 15 feet deep and covered an area 900 by 400 feet. Slope angles in the starting zone ranged from 36-38 degrees.

This human triggered slide occurred near Daisy Pass north of Cooke City. The slide was triggered by a snowmobiler climbing the slope. The slide was triggered after the snowmobiler made the turn and was on his way down. He deployed his flotation device and was shot out the toe of the debris with his sled. Photo J. Kunzman  

These sides failed on slopes with a similar aspect and elevation. Both were triggered by snowmobilers. Human triggered deep slabs are a major problem around Cooke City right now. Once triggered, deep slab avalanches often produce high consequence situations. Photo J. Kunzman  

This slide occurred on the south face of Mt. Abundance north of Cooke City. The slide was triggered by a snowmobiler climbing the slope. He was caught and buried with only his head sticking out. He suffered two broken legs and was flown by helicopter to the hospital in Bozeman. The slide failed on facets near the ground. Photo B. Fredlund