Out of Advisory Area

good day with kiddo

Skiers observed natural avalanche activity just outside the Cooke City advisory area in Yellowstone National Park on Monday. Photo: S Gill

Skiers observed natural avalanche activity just outside the Cooke City advisory area in Yellowstone National Park on Monday. Photo: S Gill

From obs (2/5/22): "Attempted to ski the SE Couloir on Emigrant Peak today. As we approached, we noticed recent avalanche debris in the runout zone of the line. We approached carefully and it looked to be somewhat recent in the last few days. Not buried by much recent snow but also did not look fresh as of that day. I am guessing it was triggered by a collapsed cornice but with poor visibility it was challenging to see any sort of crown or broken cornice above us. We did not ski the couloir. I dug a pit in the open east facing bowl below at 9200 ft. The snowpack was between 55-75cm deep.

Debris pile from a recent avalanche on the SE Couloir of Emigrant Peak. The avalanche appears to have occurred within the last few days and was likely triggered by a cornice fall. Photo: H. Darby

Ski for scale next to debris from a recent avalanche on the SE Couloir of Emigrant Peak. The avalanche appears to have occurred within the last few days and was likely triggered by a cornice fall. Photo: H. Darby
 

Attempted to ski the SE Couloir on Emigrant Peak today. As we approached, we noticed recent avalanche debris in the runout zone of the line. We approached carefully and it looked to be somewhat recent in the last few days. Not buried by much recent snow but also did not look fresh as of that day. I am guessing it was triggered by a collapsed cornice but with poor visibility it was challenging to see any sort of crown or broken cornice above us. We did not ski the couloir. I dug a pit in the open east facing bowl below at 9200 ft. The snowpack was between 55-75cm deep. In this location, the bottom 30cm of the snowpack were very large, well-developed facets with some depth hoar. I got ECTN 14 about 45cm up and ECTX on the facet/midpack interface (30cm up). 

We turned around about 300’ up the Pitchfork in Mission Creek this morning. There was 10-20 cm thick wind slabs on the margins of the path that I think would have disappeared had we continued higher into what I’ve found in the past to be the more sheltered aspect of the couloir. But we didn’t make it that far after finding a thin graupel layer 60 cm down that was reactive in stability tests. HS was 200 cm where we dug. Hopefully the graupel problem won’t last very long and it’s obviously specific to those sorts of features but I’d imagine it’s present in similar terrain inside the advisory area as well. 

From obs (2/4/22): "Touchy surface hoar layer buried under slabs on top of old surface facets in wind protected north and east facing aspects. The layer was observed between 8400 and 9400 feet in the southern Absaroka Range, in Yellowstone National Park. Intentionally skier triggered D1 and D2 slabs 10-30cm thick." Photo: S. Rathbun