Bulletin d’avalanche

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche danger is moderating after the big loading events of last week, however possibility of triggering an avalanche remains. Watch for stubborn to touchy wind slabs below ridges around the compass rose. Triggering an avalanche on persistent weak layers is a low probability, high consequence, possibility today. Assess the conditions where you are before jumping into consequential terrain.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Strong winds, 15-20mph with gusts into the 30mph range, from the south and southwest accompanied the storm on Wednesday. Thursday the winds shifted around the compass rose to the north and east with enough power to transport snow. Today light to moderate winds will come out of the southeast to southwest.

    Watch out for lingering stubborn wind slabs particularly on north and east aspects from earlier in the week, and small touchy wind slabs from the past 24hrs in unusual places today.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1.5–3

    The peak period of instability on these layers has passed since the big loading events of last week and the more modest loading this week. However, the snowpack beneath January’s accumulation remains complicated with several weak layers and crusts. Triggering an avalanche on these layers is a low likelihood, high consequence possibility. An avalanche on these layers would most likely be initiated from trigger points around protruding rocks or trees where the snowpack is shallower and weaker, or from a smaller avalanche stepping down, and could propagate above and wider than expected.

Avalanche Discussion

Big thanks to Lookout ski area for allowing us access to the ridge south of Eagle Peak yesterday.

We found a generally stable, right side up, snowpack with lots of wind effected snow on either side of the ridge. The upper snowpack, built up over the past two weeks, shows good structure with a small protentional for a 4-6” soft slab from the most recent snow on top. Things get a little more complicated deeper in the snowpack where January snow sits on top of December rain crusts and a rotten base. Yesterday we did not find information that suggests these layers are likely to fail, but due to the size of the potential slab a failure on these layers would be seriously dangerous. It’s a low probability, high consequence scenario. In addition to wind slabs, today I would watch out for sluffing of the recent storm snow on steep sheltered slopes and be aware of the potential for heavy wet snow or rain to add weight to the upper snowpack as the day goes on.

I’d like to take a moment to acknowledge the tragic avalanche accident that took place near Stevens and West Willow Peaks last week. IPAC is still working on completing a report on the incident, which will be published on IPAC’s website and the national data base soon. There’s little I can say to sum up the enormity of this loss. I guess all I can say is don’t take anything for granted, everything can change in an instant. Be mindful and take care of each other. We mourn the loss of a member of our backcountry community and our deepest condolences go out to the victim’s family and close friends.

Régions couvertes