Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Dangerous avalanche conditions will continue near and above treeline. You can easily trigger avalanches big enough to bury or kill you where the wind drifts thick slabs of snow. Use caution on any slope steeper than 35 degrees with enough snow cover to produce avalanches

Preliminary Report: On Saturday morning, December 12th, an avalanche fatality occurred in Silver Basin area of Crystal Mountain Ski Resort. See the forecast discussion below for additional details.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Consider avoiding leeward slopes 35 degrees and steeper. Steer around areas where the wind forms thick drifts and pillows. Avalanches will be the largest and easiest to trigger above treeline. You may even find drifts in open areas below treeline. Watch for tricky slopes where the wind has created subtly stiffer and more cohesive snow, like on leeward sides of mid-elevation ridges. Use a probe or pole to feel for deeper drifts. Indicators of the danger are recent avalanches, cracks shooting through the snow, and wind transported snow.

    (12/11/2021) A crack in a wind drift. Cracks broke to interfaces ~20cm and ~40cm below the surface within storm snow layers. E, 5180ft, SPMR Photo: Josh Hirshberg

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    You may be able to trigger avalanches on slopes steeper than 35 degrees where you find hard over soft layering within the top 2 feet of the snowpack. Other signs of instability are recent avalanches, cracks in the snow, and test slopes that slide easily. Quick snowpack tests can be useful to assess if the snow could slide before you commit to steeper terrain.

    (12/11/2021)

    Investigating the crown of a skier triggered avalanche. This slide ran within the new snow 40cm below the surface and broke about 75 feet wide. SS-AS-R1-D1-S. 5100ft, SE, Big Chief Mtn

    Photo: Josh Hirshberg

Avalanche Discussion

Saturday was a busy and active day in the backcountry. Observers near the top of Stevens Pass reported natural and triggered avalanches. Small natural avalanches within the new snow occurred at 5500ft, NE on Big Chief mountain and on Cowboy Ridge at Stevens Pass Resort. Nearby, another observer reported triggering a size D1 avalanche in the new snow (41cm below the surface). This slide was 75 feet wide, ran about 250ft, and was triggered on a SE aspect at 5,180ft. On Saturday, observers reported about 2 feet of new snow in the past 24 hours.

Expect another 8-10 inches by the end of Sunday. Since December 4th, 3 feet of snow has accumulated over a stout crust. Observers have reported varied test results (some planar and sudden) just above the early-December crust. As the snowpack gets stressed from heavy snowfall, keep an eye on this interface. You may be able to trigger avalanches that break wider than expected on the crust. 

It's early season, and snow cover is still shallow. If you're sliding on snow, watch for hitting rocks, logs, or open creeks. 

Preliminary Report: On Saturday morning, December 11, a party of six backcountry tourers were traveling uphill in a closed section of the Crystal Mountain Ski Area known as Silver Basin. The party triggered a large avalanche on a N to E facing slope at approximately 6500’. While all members of the party were initially caught, four were partially or fully buried. A nearby party of two witnessed the event and immediately assisted in the rescue. Crystal Mountain Ski Patrol was also notified and responded to the scene. Unfortunately, one of the fully buried victims did not survive. NWAC and Crystal Mountain Ski Patrol will collaborate to conduct an investigation. Our deepest condolences to the family, friends, and community.

Uphill travel reminder: Check in with your local ski area this weekend regarding terrain access and parking updates. For the SPMR uphill hotline call 206-812-7847. Closed ski areas often share a similar snowpack and avalanche hazard as the surrounding backcountry. You may also encounter other hazards like active avalanche mitigation, unmarked obstacles, snowmobiles, groomers, and other heavy equipment as ski areas prepare to open. Be prepared to make your own assessments and handle emergency situations.

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