This natural hard slab avalanche likely released 2-3 days ago. It was 200 feet wide and 100 feet vertical and measured 37 degrees at its steepest. The slope was an east facing wind loaded hill at 9,100' located off the groomed trail. Small slides like this are indicative of further instabilities throughout the range. We saw many other avalanches in Sunlight and Carrot Basins.
A natural avalanche released on the layer of big, faceted grains. The slab was up to 2 feet thick. This snowpack stricture is similar throughout southwest Montana. Slab + Weak Layer + Steep Slope + Trigger = Avalanche.
The southern Gallatin Range, the entire Madison Range, the Lionhead Area near West Yellowstone, the mountains outside Cooke City and the Washburn Range:
Surface Hoar - Nice to look at on the surface. Not nice to look at 1-2 feet below the surface.
The southern Gallatin Range, the entire Madison Range, the Lionhead Area near West Yellowstone, the mountains outside Cooke City and the Washburn Range:
The southern Gallatin and southern Madison Ranges, the Lionhead Area near West Yellowstone, the mountains outside Cooke City and the Washburn Range:
An avalanche occurred in the Lenin ski run on Lone Mountain at the Big Sky Ski Resort in southwest Montana at approximately 1200 hrs on 12-13-09.
A pencil hardness (very dense) wind slab is sitting over weak, unstable facets. The instability was worse than we were expecting (CT4,Q1; ECTP14,Q1). Skier compaction will NOT effect this weak layer. We will be tracking it closely, but it looks like it'll last a while. Watch the Saddle Peak video (12/17/09) to learn more.
