It is still possible to trigger an avalanche on facets and surface hoar that are now buried 1-3’ deep from the past week’s snow and wind. The few inches of snow over the past two days is not adding any significant stress to the snowpack, but these persistent weak layers still need more time to heal. The most likely slopes to trigger a persistent slab avalanche will be those that have seen recent wind loading, with relatively stiff snow at the surface.
As we get further out from the last major loading event, we are going to get less direct feedback from the potentially unstable snowpack. This leads to a higher level of uncertainty while trying to assess stability, which requires maintaining wider margins of safety. For now, that means sticking to terrain that minimizes the consequences if you do trigger an avalanche. You can do this by avoiding slopes with exposure to terrain traps like cliffs, rocks, trees or gullies, and staying off big terrain for a little while longer. Just like we saw with the weak layers we dealt with for most of February, this will get better over time and we will once again be able to step out into bigger terrain. But for now we just need to be patient, and give the snowpack a little more time to gain strength.
Wind Slabs: The winds are expected to bump up slightly from what we saw yesterday, which may increase the likelihood of triggering a wind slab avalanche 6-12” deep. While these are not expected to be particularly large today, they will have the potential to step down to the weak layers discussed above, creating a larger avalanche. Be aware of active wind loading, and keep an eye open for signs that a slope has been recently loaded. This will feel like stiffer snow at the surface, and may have the appearance of a smooth, rounded pillow. If you experience any collapsing (‘whumpfing’) or cracks shooting out from you or your machine, the snowpack is giving you clear signs that it is capable of avalanching.
Sluffs: Steep slopes that have been sheltered from the wind have around a foot or more of loose snow sitting on top of firm surfaces. It will be easy to trigger dry loose avalanches today, and they can pick up enough volume and speed to carry a person. While it is unlikely they will be big enough to bury you, they can be dangerous if they drag you into terrain traps like cliffs, trees, rocks, or gullies.
This weak layer of surface hoar was buried on 3/9, and is now 1-3′ deep. Photo taken 03.06.2021.
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