New avalanches and old avalanches

New avalanches and old avalanches

Date
Activity
Snowmobiling

Ian and I rode north of Cooke City, had good visibility, and saw terrain from Daisy Pass to Mt. Abundance back to Lulu Pass, around the south side of Scotch Bonnet, then back around the north side of Sheep Mtn. to Round Lake.

We saw many avalanches of various types and ages. Some occurred today and within the last 24 hours and some were up to a week old. Avalanche types ranged from 3-6' deep and broke on weak layers near the bottom of the snowpack to shallow soft, fresh wind slabs, and we saw one 3-4' deep slide that looked like it broke within recent new and wind-drifted snow (photo attached, north end of Henderson). 

The most notable avalanches were 2-3 slides that happened today:

1) When we rode away from our snowpit on Mt. Abundance we saw a fresh 3'deep x 10' wide slide that we might have remote triggered from the flat ridge above (photo attached). 2) About 45 minutes later, from a couple miles away, we saw a 4-6' deep avalanche that happened since we had been there, about 1000' up the ridge from our snowpit (photo). This slide was either natural or remote triggered by riders about 1000' away who were there after we were. 3) An avalanche on the south end of Henderson Bench that looked fresh and someone else thought happened today. This one was 6' deep and broke at the bottom of the snowpack.

There was also a very large avalanche on the north side of Fisher Mtn. that happened at some time in the last week (could have been 48 hours to a week old), regardless of timing, this slide further shows the deeper weak layers are a real problem as snowfall continues to adds weight to the snowpack.

Out snowpit produced an ECTX and had 4' of snow above a layer of surface hoar buried one foot off the ground with facets below.

Region
Cooke City
Location (from list)
Mount Abundance
Observer Name
Alex Marienthal