Bulletin d’avalanche

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Human-triggered slab avalanches are possible. These slides have the potential to fail near the ground, dislodging the majority of the season’s snowpack. Sticking to lower angled terrain and avoiding areas where snow cover is thin are the best ways to reduce your risk.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    There are two primary persistent weak layers to keep in mind. The first exists under storm snow from early January (roughly 2-3’ deep) and the second lies near the base of the snowpack. Being involved in an avalanche failing on either of these layers would be a scary and likely unsurvivable experience. 

    Dealing with deeply buried persistent weak layers is challenging. You’re not likely to benefit from the telltale signs of instability such as recent avalanches, cracking, or collapsing. Instead, you have to assume that weak snow layers exist on most slopes and adjust your travel plans accordingly. 

    The best way to reduce your chance of triggering a slide is to keep a close eye on the slope angle of the terrain you travel on and under. Avalanches are most likely to occur on slopes between 35 and 45 degrees. Likely trigger points include locations where the snow cover is thin like rock outcrops or the margins of a bowl where wind has stripped snow.

    ADDITIONAL DISCUSSIONRecent light snowfall and moderate wind built sensitive cornices and small wind slabs near exposed ridgelines. Cracks shooting from your boards or sled are the best clue that you’ve found a sensitive slab.

Avalanche Discussion

Yesterday we dropped the danger to MODERATE. Although any drop in danger gives the appearance of a large step toward safer conditions the reality is often much more nuanced. We’re now several days out from our last significant snowfall and the most recent slab avalanches occurred over the weekend. As time passes, the chances of triggering a slide are slowly decreasing (as with the danger), but the size and consequence of an avalanche remain the same. 

The scenario we're facing is commonly referred to as “low probability, high consequence,” or LPHC for short. LPHC events are tricky to deal with, in the backcountry and in life in general. You must decide what threshold of risk is acceptable. 

In the absence of obvious signs of instability choosing what terrain you’re comfortable exposing yourself to can become a bit of a head game. You might find it helpful to decide what is “off-limits” before leaving the house. This reduces the potential for other groups to influence your level of risk. It also removes the temptation to accept more risk based on information (like tracks on a slope) that has no bearing on the stability equation. 

Slides like these (photo, photo, photo) are what we’re gambling against. Build a safety margin into your travel plan and stick with it. 

Details from Wednesday's Avalanche Accident in Baker Creek:On Wednesday, January 15th, 2020, a snowmobiler was caught and killed in an avalanche in the Baker Creek drainage, approximately a half-mile northeast of Baker Lake. This video contains preliminary information collected during a site visit last week; a full accident report will be published in the coming days.

Régions couvertes