Persistent Slab in Grave Creek

We visited the site of Sunday's snowmobile triggered avalanche in Grave Creek in the northern Whitefish Range. 

• The slide occurred while a single snowmobiler was side hilling a steep (40 degree) road cut at 4800' elevation. Members of this group had side hilled numerous road cuts similar in steepness prior to triggering this slide. 
• This was a Persistent Slab avalanche that failed in a thin layer of facets on top of the 2/2 (Groundhog Day) crust.
• The crown varied in depth between 14-18", was 40' wide and ran 50' vertical piling 3-4' of debris onto the shoulder of the road.
• We found out, after the fact, that there were 2 snowmobile triggered avalanches on Sunday in the Graves Creek area. The reporting party mentioned that the one that was off trail was larger than the one we visited. This same individual mentioned that there was a lot of snow sliding on Sunday.