11-12

 The snowpack on Mt Ellis consists of a variety of faceted layers.  Some are more dense than others, but the fact is if this slope gets a load it will likely produce avalanches.  Photo: GNFAC

 Surface hoar has been found in many areas in the northern Gallatin Range.  Photo: Alex Marienthal

The Bridger, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone and mountains around Cooke City:

The Bridger, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone and mountains around Cooke City:

This natural avalanche occured near Cooke City on a NE facing slope near 9100 ft.  This avalanche shows three things: 1)Cornices near the ridgetop indicate wind loading.  2)Weak facets near the ground have no problem fracturing across tree covered slopes.  3)If avalanches are occurring naturally, then they can surely be triggered by a skier or rider.  Photo: B. Fredlund

This is the track and runout from an avalanche triggered by the Moonlight Basin Ski Patrol on a heavily wind loaded slope.  Being caught in an early season slide is serious and likely to cause serious trauma.  Photo: GNFAC

This avalanche was triggered by explosives by the Moonlight Basin Ski Patrol; however, this slope was heavily wind loaded and could have easily been triggered by a skier or rider.  The snowpack is thin and weak with very large facets sitting under a fresh wind slab.  This is a classic recipe for an avalanche.  See a snowpit from the adjacent slope at: http://bit.ly/tL6j78  Also, see a video: http://bit.ly/vyZgut  Photo: GNFAC

The Bridger, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone and mountains around Cooke City:

The snowpack is relatively simple. Generally you can find two basic situations: