Quick report
- Cracking
- Observed
- Collapsing
- Observed
We experienced many very large collapses. Associated cracking traveled out thousands of feet from the point of collapse, sometimes propagating through improbably pieces of terrain/snow.
Weather
Started in tour in late morning, there was a brief break in precip between storms. Then snowing S1-S3 throughout the rest of the tour. Steady moderate winds with strong gusts on exposed ridgelines, blowing out of the S/SE. We returned to the truck after dark, it felt like it may have rained a touch down lower (below 6,000') during the day, but was dumping fat flakes on our drive out.
Snowpack
Snow since 2/1 has settled into a 50-60cm thick slab. We observed and triggered some small wind slabs and small dry loose sluffs within the new snow. We did not observe direct signs of instability at the 2/1 interface.
A snowpit dug at 8,600' on NW face where HS=120-130cm we found 2/1 down 55cm and 1/6 down 90cm. 1/6 returned CPST 30/150 END with the cut started on 1/6 and 70/140 END with the cut started on 11/30. PST returned 30/110 END. Much of the January snow has settled into a 1F+ to P- slab here.
Our weak layer exists on most slopes, and is impressive for the avalanches it has already created. The very dense slab on top of it is somewhat unusual for this area. The combination of these two infrequently occurring phenomena has and is sure to continue to create unusual avalanche conditions.
Avalanche
We observed a handful of natural avalanches that failed since my previous trip in this area on 2/2. All of these were at least D2, and 2 were D3s. We also may have remotely triggered a set of avalanches that summed to a D3 from two bowls away: we triggered one very large collapse, followed by the echo of what sounded like an avalanche bouncing off the hills behind us. Later in the day, we observed this set of avalanches. If we did not trigger it then it occurred naturally that day.