Likelihood ?CertainVery LikelyLikelyPossible
Size ?HistoricVery LargeLarge
The abundant snow that fell on December 18th-19th has created a cohesive slab 2-3' thick across the area. This slab overlies multiple buried weak layers. Stability tests show that both this slab layer and buried weaknesses are gaining strength; however, if triggered they will create very large avalanches with the potential to pull in snow from lower angle slopes that are adjacent should this slab move.
Today we travelled into the Eastern Cabinets where we again heard multiple collapses on weak layers below 5,000'. These sounds are a sure sign of instability and we noticed that they were most prevalant in terrain with a thinner snowpack and anchored terrain. They also proved to be surprisingly stubborn in stability tests. Conclusion-some very weak snow exists below 5,000'; however, it is unlikely to pose a threat in most areas due to vegetative anchoring. Strong caution is advise at or below this elevation if you are in areas that are naturally open and void of vegetation. As we travelled into higher terrain the snowpack thickened and stability tests showed that the snow that fell last weak has gained significant strength. We had consistant results with failures occurring 32" below the surface, again failing on weak facets that are resting on the Thanksgiving rain crust.
Avalanche conditions change for better or worse continually. Backcountry travelers should be prepared to assess current conditions for themselves, plan their routes of travel accordingly, and never travel alone. Backcountry travelers can reduce their exposure to avalanche hazards by utilizing timbered trails and ridge routes and by avoiding open and exposed terrain with slope angles of 30 degrees or more. Backcountry travelers should carry the necessary avalanche rescue equipment such as a shovel, avalanche probe or probe ski poles, a rescue beacon and a well-equipped first aid kit. For a recorded version of the Avalanche Advisory call (208)765-7323.
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