Wind slab avalanches near Cooke

Wind slab avalanches near Cooke

Date
Activity
Snowmobiling

We rode over Daisy Pass out to Mt. Abundance, then behind Fisher and around Scotch Bonnet back to Lulu Road. Snowed light this morning with partly sunny skies mid-day. Wind was moderate and gusty out of the west. We were able to see most terrain north of the passes. Clouds obstructed great views of east Henderson and east Miller. 

We saw a fresh natural wind slab near Wolverine, R1-D1.5 (photo attached). We watched two snowboarders trigger separate wind slabs, while riding one at a time in avalanche terrain, on the south side of Scotch Bonnet (photos attached). They rode away safely. These looked 12" deep and 20' wide, and entrained snow to run a good distance, R1-D2.

We dug a pit on the south shoulder of Mt. Abundance and had an ECTX. There were some density changes in the recent snow that might contribute to wind slabs or storm slabs breaking easier for another day or two, but they seemed more stubborn than yesterday.

Wind slab avalanches were the primary concern today, and I expect they will continue to grow tonight and with any more wind tomorrow. They will remain likely and easy to trigger for at least another day.

We have not seen any persistent slab avalanches breaking below last week's snow or deeper over the last few days. This is a good sign, but I am not ready to write off the possibility quite yet. It is worth continuing to dig and test for buried weak layers for now. The avalanche on east Henderson last Tuesday and the avalanche on Crown Butte last Monday were deep and possibly broke on persistent weak layers, and were on heavily wind loaded slopes. These types of areas are worth avoiding and where a bigger avalanche may be possible to trigger.

 

Region
Cooke City
Location (from list)
Scotch Bonnet
Observer Name
Alex Marienthal