10-11

This avalanche was triggered by a falling cornice.  It occured on a NE aspect and broke about 14 inches deep. Photo: anon.

This layer was found on all east facing slopes above Bear and Middle Basins.  It is less common on west aspects where strong westerly winds destroyed it on most, but not all slopes.  Surface hoar is notorious for catching people off guard.  Assume it is on all slopes until you definitively prove that it doesn't exist on the slope where you hope to ski or ride.  Photo: GNFAC

The northern Madison Range and mountains around Cooke City and Washburn Range:

On December 11th two skiers triggered this avalanche near the ridge line as they ascended the slope (ENE) on their skis.  It broke up to 30" deep and was all wind-loaded snow from the week before. The skiers were caught, but managed to stop before the slope steepened and flushed through a narrower gully. The avalanche ran 1000+ feet vertical and propagated around the corner.  Photo: Anonymous

On Sunday December 12th, skiers intentionally triggered these small wind-loaded slopes.  They broke 10-18" deep and are indicative of the spotty nature of instability since they did not find anything similar on the upper mountain. Photo: Josh Gage

Over the weekend a skier triggered this northeast facing slope at 9,100 feet on Yellow Mountain north of Big Sky. This 15" wind slab broke on buried surface hoar and facets.  It ran 80 yards across and ran 800 feet vertical. Photo: Anonymous

This small slide on the Miller road from the groomer broke on facets sitting on an ice crust. This combination was created December 5th.  It's called radiation recrystallization and we made a video of this layer forming.  Photo: Beau Fredlund

The mountains around Cooke City:

Small avalanches like this are indicative of buried weak layers and the danger to be found on bigger slopes. Photo: Beau Fredlund

 Touring up Republic Peak natural avalanche activity was seen on many slopes. Photo: Beau Fredlund