24-25

We got lucky in the Centennials with great snow and good visibility. There was about 20" of new snow from this weekend's storm. We covered 35 miles of backcountry riding and got eyes on a lot of avalanche terrain from lower elevation slopes, to Jefferson Bowl, the terrain in and above Hellroaring Creek, and East Hotel Creek. We didn't see any avalanche activity. However, we observed shooting cracks in drifts and triggered small wind-loaded slopes and cornices. So, human-triggered avalanches on wind-loaded slopes are likely. 

We dug three quick pits but prioritized getting eyes on terrain over in-depth snowpack analysis: 

Low-elevation slope on Sawtelle - NE @ 7600' on a slope with no wind effect: ECTX in a 160 cm deep pit

Above Hellroaring - S @ 8400' on a wind loaded slope: ECTP1 6" deep (wind slab) and ECTP21 20" deep (wind slab)

Arange - SW @ 8700' non-wind-loaded slope: ECTP21 20" deep on facets below a melt-freeze crust 

Travel Advice: 

1. Avoid wind-loaded slopes
2. While stability on non-wind-loaded slopes seemed good, it snowed a lot. So, I would either carefully assess for instability in the upper 3 feet of the snowpack with an ECT , or I would give it a few days to settle out before getting on steeper, non-wind-loaded slopes.

The danger was CONSIDERABLE on wind-loaded slopes (human-triggered avalanches likely) and MODERATE in non-wind-loaded terrain (human-triggered avalanches possible).

Cornice broke in between north and south saddle peaks.  The initial propagation width was hard to distinguish.  Maybe 50 feet.  About 18 inches deep at height of crown.  Photo: Anonymous

Cornice broke in between north and south saddle peaks.  The initial propagation width was hard to distinguish.  Maybe 50 feet.  About 18 inches deep at height of crown.  
 

Skied down Rocky Rib and then into south east facing trees that follow the path.  At the Argentina/ Shushmans traverse elevation there was a visible 2 foot wall and the slide had continued over the roll below.

From obs: "2/17 Immediately noticed signs of wind loading and wind slabs on NE-E aspects once in the basin. New cornices have formed in the last couple days along the North ridge to the summit. Cornice collapse on the summit triggered a small wind slab on an isolated slope." Photo: R. Rintala

From obs: "2/17 Immediately noticed signs of wind loading and wind slabs on NE-E aspects once in the basin. New cornices have formed in the last couple days along the North ridge to the summit. Cornice collapse on the summit triggered a small wind slab on an isolated slope." Photo: R. Rintala

From obs: "3 small storm slabs observed on steep terrain of Bridger Ridge (E aspect observed from wolverine woods) Attached is a photo of the deepest likely ~12in crown. No observed wind slab development below 8100ft. No propagating test results in pits dug Lower ramp, and wolverine woods." Photo: L. Butler