This snowpit was dug near a recent natural avalanche. Facets under the new snow were obvious while snowmobiling because the track would carve into the facets and make the powder seem deeper than it was. When we stepped off the sleds, we would immediately sink to the ground. See a photo of the avalanche at: http://www.mtavalanche.com/images/12/small-natural-avalanche-cabin-creek Photo: GNFAC
This small natural avalanche was spotted near Cabin Creek under Skyline Ridge on a South facing slope at 9000 ft. Photo: GNFAC
A small cornice drop sympathetically triggered a larger slide along the ridge. Any slope that has been wind loaded will be sensitive to the weight of skier or rider. Photo: GNFAC
Weak layers near the surface and near the ground are producing unstable test results in Middle Basin. Photo: GNFAC
The Lionhead area near West Yellowstone and the mountains around Cooke City:
Near West Yellowstone and Cooke City, the story is simple. Heavy snowfall and high winds have created very dangerous avalanche conditions.
This avalanche was triggered by a skier on the adjacent low angle slope on "Town Hill" which is the terrain just above Cooke City. The gully where this avalanche occured had received a heavy load of wind blown snow. Another avalanche was observed nearby that was triggered by a falling cornice. Photo: B. Fredlund
We triggered this avalanche from a cornice drop. It propagated about 600 feet wide. It broke on the thick layer of facets underneath the wind-loaded snow. We also triggered three more along the ridge: one from a cornice drop, one from a collapes and another remotely. Photo: GNFAC
