Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

With all of the recent snow, you can trigger a number of different types of avalanches that could be big enough to bury you.  Cold temperatures and cloudy skies are keeping the snow light, dry, and easily blown by the wind. Be prepared for the coldest temperatures of the season.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Avalanches big enough to bury you are likely near and above treeline. Simply put, there's a lot of light, dry snow out there that's making it easy for you to trigger an avalanche. Use caution on slopes steeper than 35 degrees. Steer around convex rolls and steeper portions of slopes. Make sure to expose only one person at a time to avalanche terrain and regroup in safer areas, well out from under steep slopes. Quick tests (hand shears and tilt tests), and testing small inconsequential slopes with your weight are good ways to assess how easily the snow can slide. 

    Many of the avalanches that you could encounter will be classic storm slabs in wind-sheltered about 1-1.5 feet deep. These may even exist on slopes that are typically wind exposed. You may encounter slabs of freshly wind-stiffened snow, though wind slab distribution may be more isolated and less predictable than with typical wind events. Older slabs formed from northwest winds on the 23rd are buried under recent snow and are now harder to trigger.

     

    (12/25/2021)

    A skier triggered avalanche (size D1) about 1 foot deep in recently fallen snow. Arrowhead Mtn, 5800ft, W. 

    Photo: Stephen Semanski

  • Loose Dry

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

    You can trigger loose avalanches in the surface snow on slopes 40 degrees and steeper. While these avalanches are typically small and can be easy to manage with experience, they can be dangerous especially around terrain traps. Watch out for traveling in steep terrain with features like gullies, cliffs, and trees, where any avalanche could have serious consequences.

    (12/23/2021)

    Loose dry avalanches have been easy to trigger on steep slopes.

    Photo: Joe Dellaporta

Avalanche Discussion

We've been in a storm cycle since the Solstice, and the snow keeps adding up. Storm totals in that time are 3 feet and counting. Temperatures will continue to drop to rarely seen frigid lows. This may mean that you could trigger avalanches on storm interfaces for longer than normal. Be proactive around frostbite and cold weather injuries. Winds, while light could transport the light, dry snow near ridgelines. The snow is deep, and observers have reported difficult travel conditions and potential for snow immersion hazard. It's time to stay away from tree wells and keep your partners within sight and voice contact.

In the past 2 days, avalanche control teams at SPMR and WSDOT triggered numerous avalanches, both soft slab and loose dry slides in the new snow, up to size D2. On Saturday, observers on Arrowhead Mountain triggered a number of small storm slab avalanches (about 1 foot deep) on a west aspect near treeline, the biggest of which broke about 40 feet wide. They also reported a number of small, triggered loose avalanches at all elevations and isolated and thin, fresh wind slabs near treeline in unpredictable locations. 

A number of crusts may be found in the mid and lower snowpack from early to late December. They aren't expected to be problematic for avalanches at this time but are worth monitoring.

Régions couvertes