Blowing snow and wind slab avalanche on Anderson Peak

I spent the night at Anderson Peak on March 10 and experienced stronger than forecast NE winds overnight. After sunrise on March 11, moderate to intense blowing snow was noted as NE winds continued. Just before 10 am I noticed another party on the ridgetop on the SE side of Anderson Peak. This party intentionally collapsed a cornice and triggered a size D1 wind slab avalanche on a NE aspect in above treeline terrain at about 8,550'. I then watched a snowboarder descend the bed surface without further event.

I then followed the drifting snow to a newly formed wind pillow on the top of a WNW aspect and performed a few ECTs. I observed repeatable ECTP results in the 18 to 24 tap range failing 40 cm (16 inches) down at the bottom of the newly formed wind slab. The slab was P hard with an old snow weak layer that was 4F- in hardness.

With signs of unstable wind slabs on both sides of the ridge, we scrapped plans to tour south and exited the area to the north where we could avoid areas of wind slab. While touring out of the area to the north, we encountered 1 cm thick melt freeze crust that had formed on solar aspects during sun breaks on March 10 up to about 8,000'.

Cloud cover cleared quickly from this area today, giving way to full sun most of the time. Our low point of travel today was 7,200' and we saw no signs of loose wet instability above that elevation, only minor amounts of snow surface warming.