We skinned and climbed to the summit of Lake Peak. We ascended on the North side, along the minor, rocky ridge that faces North. At the summit, visibility was very low.

We ski cut the slope at the very top of the NNE chute of Boulder Basin. The surface layer quickly began to slide, with some minor, lateral propagation. Due to the low visibility, we could not see how far it went, but we thought we heard a sliding sound continue for longer than expected.

The surface layer slid on top of a strong, hard, and somewhat icy crust. I assume that crust was a wind crust from wind events in recent weeks.

We skied down one at a time on the crust, stopping in safe zones that were protected by rock and terrain contours. The hard crust supported us, and it did not break. It also supported the surface avalanche, which grew considerably from the short, ten foot wide ski cut. It grew to a maximum width of 150 feet, or so, and slid several hundred vertical feet down to where the terrain levels off.

We were surprised by how far it ran and how wide it got. The depth of the slide was fairly shallow, with a maximum debris depth of 12-24 inches at the bottom.

We were also surprised by how far down the hard crust extended. While it is not uncommon to see wind crusts near the top of ridge lines and summit, this crust was still quite hard all the way down to 10,000 feet (que1,000 feet down from the summit). Apparently, the winds really whip around in that White Pine Cirque, which is a fairly wide open cirque with a lot of wind exposure.

Neither of us were caught in the slide. We remained safely above it all. The skiing down the avalanche path was not very good. Between the hard crust and the debris field, it was a rough descent.

During a brief stop at about 10,500; we checked the snow layers with a quick ski pole punch. Below the hard wind crust was a good 6-12 inches of soft snow. A weak layer.

Thankfully, the wind crust was strong. It did not break under our weight, or the weight of the surface avalanche that we deliberately triggered. If that wind crust ever breaks, a much deeper avalanche event could occur on that slope.