Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

While not likely, you can trigger avalanches involving very dense, 2-4+ foot thick slabs on a variety of slopes today. The first sign of instability may be the large avalanche you trigger.  Smaller avalanches can be triggered on wind-affected or steep, sheltered, shady slopes. Choose simple terrain free of terrain traps to reduce your risk. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    What is it? A very dense, 2-4+ foot thick slab stands over buried weak layers of facets or crust + facet combinations. Triggering an avalanche on these layers is not likely, but the outcome of doing so would be catastrophic. Watch the video to the right/above to understand this problem better.

    Where is it? Most slopes harbor these layers. You'll find crust + facet combinations on sunny slopes and small facets on shaded slopes. We are still tallying up the historical amount of slides produced by these weak layers (map, list). 

    How can you recognize it? The first sign of instability may be the large, destructive avalanche you trigger. Tracks on a slope don't indicate it is good to go. These slides may break much wider and further above you on the slope than expected. Unless you dig down to confirm the weak layer exists, you might assume the snowpack feels good under your feet or sled. And if you take the time to dig down, don't trust the results of your stability tests. They serve little help when dealing with such a dense slab overlying this weak layer. 

    How can you manage it? The only way to eliminate your risk of encountering one of these devastating slides is to avoid avalanche terrain and terrain exposed to hazard from above. I know that's not satisfying to hear. You can reduce your risk by avoiding slopes steeper than about 35 degrees—especially large avalanche paths and those with ugly consequences if caught in a slide. Remember that even small slopes can have high consequences when dealing with very dense slabs. These slides can be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes.

    ADDITIONAL DISCUSSION: Small slabs of wind-drifted snow may also be reactive to your weight today. Small loose snow avalanches can occur on very steep, sheltered, and shady slopes. These slides can knock you off your feet and carry you through cliffs, trees, gullies, or other terrain traps. These smaller avalanches can be effective triggers for the large persistent slabs described above. 

Avalanche Discussion

You can still go out and trigger the same catastrophic avalanches as in previous days. The underlying persistent slab problem continues to drive my terrain selection to be in simple terrain free of terrain traps and large features. It should only take a visit to one of the massive debris piles (refer to the Avalanche Database) that took out trees and barreled down through large avalanche paths to remind you of the consequences of triggering one of these sleeping giants. 

Be on the lookout for different generations of wind-loaded slopes in the alpine. These slabs are more problematic on the shady slopes after the sun likely cooked down any fresh snow yesterday. Moderate southerly winds will make easy work of moving new snow into thin, small slabs today.  If the snow pounds down faster and more than expected, be aware of growing slabs. Triggering these small slabs can add more weight to the snowpack as they move downslope. They can serve as fresh triggers to wake up the weak layers buried deeper in the snowpack. Move away from wind-affected slopes in avalanche terrain, where the snow is becoming deeper and denser.

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