09-10

A snowmobiler triggered this avalanche in the Bridger Range north of Ross Peak on Wednesday 1-28.  A shallow snowpack and buried facets a foot off the ground continue to make avalanches possible in the Bridger Range.  Photo by GNFAC  

From an email, "...It occurered in Sunlight Basin toward the west end of the bowl. This one released as soon as I made my turnout at the top, so I rode down in the motion of the slide.  As seen in the photo, this is a north facing slope, ~40 degrees, 12" crown, ran for 100' downhill, and was 100' wide. The crown showed that basically all of the new snow we have recieved this past week let loose from the hill.

This avalanche was triggered on Jan 28 as a snowmobiler approached a small slope and shows the sensitivity of buried facets near Big Sky.  Photo: S. Reznicek

This layer of buried surface hoar is a problem in the southern Madison Range. Its not widespread and seems to be absent on south facing slopes and high alpine slopes, but I found it on many others.  As I skinned on the flats my partner and I got a huge "whumph" and I could see a crack 200 feet away on a small hill.  It fractured on this layer and answered the question, "Can this layer propagate a fracture?" with a resounding YES.  Photo: Doug Chabot