60cm of storm snow over the past week has formed a dangerous and unpredictable windslab. Crowns up to 2m deep and a km long have been seen. Several of these stepped to ground and ran into the valley.
Large cornices on lee features with some visibly detached. Those that may release would likely trigger a large avalanche. Give them a wide berth.
The widespread observations and explosive work creating large and deep avalanches indicates that many went on this deep layer particularly where the snowpack is shallow and in rocky start zones. Involvement in one would be fatal consequences.
Deep persistent slabs are best managed by:
Cornices are best managed by:
Thursday will be -3 to -6, light to moderate SW winds, clouds with some sun, and flurries. Friday will be much the same except for maybe more sun than cloud in the afternoon and -6 to -12 temperatures. Expect afternoon warming if sun comes out.
Wind slabs up to 1.5m deep found at and above treeline. Large cornices are present. The mid-pack has several crusts and persistent instabilities of facets and surface hoar. Closer to the ground is a weak base around the November rain crust and depth hoar. Time is required for the snowpack to strengthen after Saturday's storm loading.
No patrol Wednesday. Saturday and Sunday was a widespread cycle with crowns a kilometer long and 2m deep. Some were size 3.5 and ran full path stepping to basal layers near the ground. Less activity at treeline with size 2-2.5. Monday's control produced numerous size 3 avalanches from the alpine.