Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a large, 1.5-2.5 foot thick slab avalanche that fails on weak snow near the ground is today's primary avalanche concern. Such slides are most likely at upper elevations and on shaded middle elevation slopes (those facing E-N-W). You aren't likely to observe obvious signs of instability before triggering such an avalanche, and slides can be triggered after many skiers and riders have crossed a slope.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Weak snow at the base of the snowpack drives the primary avalanche concern today. A 1.5-2.5 thick slab of dense snow rests uncomfortably on top of this weak snow. This combination of slab + weak layer exists on all upper elevation slopes and on shaded middle elevation slopes (those facing E-N-W). If you dig down on shaded slopes you'll find an obvious layer of very weak snow near the ground. On slopes that face the sun you'll find a less-obvious layer of small facets on top of a stout melt-freeze crust

    As the days tick by without significant loading, obvious signs of instability have decreased. Reports of large collapses have become much less frequent and the most recently observed large avalanche failed roughly 3 weeks ago. The likelihood of triggering one of these slides is decreasing, but not going away. Tracks on a slope are not an indication that the slope is stable — avalanches may be triggered after many riders have crossed a slope. 

    You can eliminate your risk of encountering one of these large slides by steering clear of avalanche terrain harboring this combination of slab + weak snow. If you are planning to enter avalanche terrain, spend a bit of time thinking about the consequences of triggering a slide. Slopes with terrain traps at the bottom and with trees and rocks that you can get dragged through amplify the consequences of triggering an avalanche.

Avalanche Discussion

UNEASY EQUILIBRIUM

The most recent large avalanche observed in our area occurred on December 9th (photo here). Less than one foot of snow has accumulated in this zone in the intervening 3 weeks. This extended period without significant loading has allowed the snowpack to reach an uneasy equilibrium. Stability has gradually improved and the likelihood of triggering avalanches has gradually decreased. Unfortunately, due to the nature of our snowpack, the chance of triggering avalanches involving the weak snow at the base of the snowpack won't go away until we see either an extended cycle of melt and freeze on all slopes or until we add a significant amount of snow to the snowpack (and let the dust settle from the resulting avalanche cycle). 

Avoiding avalanches is simple — all you've got to do is avoid avalanche terrain and terrain exposed to overhead hazard. We can choose to travel like this every day and never risk being caught in a slide. Of course, if you are hoping to ski or ride in some steeper terrain, that is a pretty unsatisfactory solution.  As stability gradually improves, the amount of terrain that we can reasonably enter increases. The word reasonably is doing a lot of work in that sentence. Entering avalanche terrain is a game of chance right now and one woman's reasonable may feel reckless to somebody else. We get to decide what is a reasonable level of risk for us on any given day. The most important piece of this puzzle is to be honest with yourself about the risks you are taking. If you head into avalanche terrain where our persistent slab problem lives, you are choosing to accept the risk of triggering a large, dangerous avalanche.

In addition to the primary persistent slab concern, it's also worth thinking about smaller loose snow avalanches today. The surface snow on shaded slopes has become so weak that it is ready to just slide down the hill in a type of dry loose avalanche known unofficially as a "facet-lanche". I triggered just such a small slide yesterday above Smiley Creek and a public observer reported a similar slide near Titus Ridge on Thursday.

Here's some suggested reading for you today from Roger Atkins: Yin, Yang, and You. This short, thoughtful paper describes the strategic mindsets that we take with us when we head into the mountains and how they can help frame our decision-making. It is written for both recreational and professional snow travelers. Give it a read and have a good conversation about it with your partner on the skin track today. 

Check out our latest Weekend Update from Brooke to get caught up on what has been happening this week with our snowpack.

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