Scary

Skied mellow north facing trees today but we witnessed a spectacle of avalanche activity and signs of instability.

• Around 1:15 pm, a R4D3 persistent slab ran off of a NE aspect at 6500’. The crown was 2.5’ thick; it wrapped across a rib that might otherwise seem safe and pulled in slabs on slopes as low as 31 degrees on its way down. It failed on the 3/24 faceted sun crust and near surface facets. We were worried that a group traveling in the area was caught so we conducted a beacon search with no signals. The debris snapped numerous trees.   Edit: We found out later this was remotely triggered by a group on the ridgeline.  
• On southerly aspects, we saw about ten D1.5 to D2 loose wet slides run today.
• We had good views of about 5 other persistent slabs that ran off of high elevation, northeasterly aspects sometime earlier in the week. One looked like it might have ran today. These were D2 to D3.
• We observed several small collapses throughout the tour around 6000’, but got one large rumbling collapse with shooting cracks that ran at least a hundred yards. This was while skinning a ridgeline where I was at least the 6th person on the skin track today. Surprisingly, the adjacent steep slope didn’t slide, just cracked.
• Pit results between 5800’ and 6200’ gave mix of hard non-propagating and hard propagating results on facets below the 3/24 crust. Unnerving point that highlights spatial variability: neither pit produced results on the actual weak layer that slid during today’s avalanche.
• We kept our slope angles mellow above 5500'. Lower down, we skied some steeper, north facing pitches with minor sluffing.