Date of Observation: 12/25/2022
Name: Zach Guy, Sierra Bishop, and Jack Caprio
Zone: Southeast Mountains
Route Description: Mount Emmons to 11,300′. We targeted southerly facing terrain in Racoon Basin and northeasterly facing terrain in Climax/Happy Chutes area.
Observed avalanche activity: Yes
Avalanches: We skier-triggered a pair of avalanches in Climax Chutes that started as facet sluffs but propagated wider as soft slabs once they started moving, entraining the entire snowpack (about 30 cm) to the ground, D1 and D2 in size. This path ran naturally around 12/6, so the old persistent slab structure was gone. We were surprised to see how wide the slabs propagated given that there was only 3″ or 4″ of soft, wind drifted snow above the faceted bed surface.
Weather: Partly cloudy skies, light winds, no precip.
Snowpack: In short, the snowpack is weak and ripe for another cycle with the forecasted storm. The snowpack is exceptionally weak on bedsurfaces of slopes that ran in early December: 2mm chained facets. We already got evidence of how touchy this layer will be from the slabs that propagated fairly wide today under only a few inches of soft, wind blown snow (4F). On southerly aspects, we got propagating results on the crust facet layer (12/20 layer) buried by a few inches of soft, windblown snow. We got a couple of collapses and shooting cracks near valley bottom on southerly aspects where recent wind drifting formed thin, hard slabs over these layers. On northerly slopes below treeline that haven’t already avalanched, slabs have faceted out and are unreactive in tests (ECTN M). Depth hoar is 4-5mm in size below a fist to 4F hard faceted midpack (1mm).
-
- Skier triggered avalanche in Climax Chutes. Started as a facet sluff but propagated wider and wider as a soft slab once it started moving. This slope ran naturally around 12/6, thus the very shallow and weak snowpack.
-
- Bed surface of a north facing NTL slope that ran in early December. Very weak facets over a crust.
-
- A closer look at the facets in the bed surface. Super weak!
-
- South facing slope below treeline, propagating results on the 12/20 crust/facet layer. Not really enough slab to be an issue here, but on a more drifted slope it would be.
-
- Snow profile from a BTL NE facing slope that didn’t avalanche in December.
-
- Photo of the previous pit. NE BTL, Happy Chutes.
