Spent 4 days at Challenge Cabin, Thurs-Sunday, so we saw the whole evolution of the storm. Thursday, 1-2'' of low density snow fell on top of wide-spread crusts, mostly on southern exposures all the way up to 6,500'. We found well-preserved, buried surface hoar on mid-elevation, protected slopes from 5,000-6,000' feet. We dug a pit at 6,500' NE aspect and were pleased to see a strengthening snowpack with no propogation, no surface hoar, and no custs. Total snow depth was 180 cm and the faceted grains at the bottom of the snowpack have gained some strength since our last time here late December. The storm rolled in Friday but did not drop as much as expected. 6'' of low-density snow fell on Friday and was not cohesive enough to form a slab. We skied N facing slopes for better snow and better stability and had minor sloughing to manage. Saturday, things warmed and 2" of higher desity snow fell atop the cold smoke. Then, consistent graupel showers dropped 1-2'' of roller balls on top of the already concerning layers. We saw a D1 slab avalanche on a south-facing slope in mixed, rocky terrain at 6,500'. The crown was estimated at 6-12'' and was likely started from a tree bomb. This was our cue that south slopes with a preserved crust were waking up to the load. We kept skiing north slopes to 40 degrees and saw no signs of instability. Winds were lighter than forecasted on Patrol Ridge. With clearing skies today, we only saw a distant rock fall in some cliffy terrain that started a point release, but no other avalanches were seen on any aspect. As tonight's storm continues, I would be extremely weary of more load on top of the layer cake of crusts, hoar, light snow, heavy snow, and graupel. As we left Maria's Pass, snow was picking up to S2.
We saw a D1 slab avalanche on a south-facing slope in mixed, rocky terrain at 6,500'. The crown was estimated at 6-12'' and was likely started from a tree bomb.
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