Quick report
- Cracking
- specific
- Collapsing
- specific
Today's experience has been humbling. We had thought that we were in sufficiently low angle terrain and far enough away from the gully to stay out of trouble. Instead, we got lucky. Thankfully, the skier that was caught was pushed from behind by the debris as it slowed and fanned out in the flatter terrain, and the faster moving debris from the second larger avalanche missed him to his left. He was not injured and only partially buried, and was able to stay on his feet throughout. We were both surprised at how far the debris ran, given the relatively smaller size of this gully. This is a reminder to give the current snow conditions a wide safety margin, and to avoid both avalanche terrain and being below avalanche terrain. As demonstrated today, at least in the South Fork area, remotely triggering an avalanche from far away and from below is a distinct possibility in the current conditions. Observed multiple signs of instability (shooting cracks, many large collapses) in any area where the wind has created slabs out of this past week's snow. This was especially true on NW-N-NE facing micro terrain feature that had been wind loaded (small gullies). This week's new snow and today's wind is creating cohesive wind slabs that are loading up a weak snowpack and not bonding to the weak sugary old snow.
Weather
- Air Temp
- 20
- Cloud Cover
- overcast
- Wind Loading
- moderate
- Recent Snowfall
- 3-6
- Snow Avail For Transport
- moderate amounts
Broken to overcast skies; elevations above 3600' mostly obscured in clouds. Light to Moderate SE winds. Snow flurries (S-1).
Snowpack
Bottom of snow pack is very weak, and very faceted. We also observed a thin crust in various places with 1-2mm facets underneath. New snow from this past week is forming stout, almost hard, wind slabs, that are sitting on the extremely weak faceted old snow. Snowpack structure is poor (upside down), propagation potential is high, and the old snowpack is faceted and weak. Any place where the old snow has been loaded, is likely able to propagate a collapse to surrounding slopes.
Avalanche
- Size
- D2.5 R3
- Type
- SS
- Aspect
- NW
- Trigger
- AS
- Elevation
- 3300 ft
Skiied up to about the red pin to look at gully, staying on the NW side, which was mostly wind scoured to the ground. Began descending just off the wind scour in marginally better snow in ~15-20 degree terrain, heading back towards the summer trail. While skiing across the lower angle terrain, we caused a collapse that propagated across approximately 200-400 ft of ~15 degree terrain and then up the NW face of the gully and remotely triggered the NW facing, ~25 degree side of the gully at about 3200. We believe that avalanche then triggered the entire upper gully, or the collapse propagated the entire length of the gully ridge up to ~3800ft. The debris came down in two distinct waves, with the initial debris moving slower and to skiers right, and the larger and faster moving second wave of debris to skiers left and directly in front of the gully as it transitions from a distinct gully into a broad slope. One skier was caught as the debris fanned out in the lower angle terrain and carried ~50-100 ft downhill, and ended up at the skier's right terminus of the debris but partially buried (to mid thigh). No injuries, and party self rescued. Debris was very chunky and blocky, indicating a thick and hard wind slab.