Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

The storm is ongoing and dangerous avalanche conditions will continue in and around the alpine areas.  You can trigger avalanches big enough to injure or kill you in areas where the wind deposits snow into deep drifts, especially in areas close to the Cascade Crest. Early season conditions exist, and obstacles may be buried just beneath the surface.

Preliminary Report: On Saturday morning, December 11th, 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

    Moderate to strong winds will continue to build slabs on lee aspects overnight and throughout the day. Precipitation will taper off at some point on Sunday, but the winds will continue.  The winds may build slabs lower on slopes than you expect and it will take time for newly formed slabs to stabilize. Avoid steep slopes near ridges that have evidence of wind loading. You are most likely to trigger wind slabs near alpine areas, but small wind slabs are also possible at lower elevations. Travel slowly and observe how the snow feels beneath you. Stiff hollow snow is a good indication that you should avoid steep slopes.  Today is a good day to stick to low-angle or wind-sheltered slopes.

    (12/8/2021)Example: Long shooting cracks in freshly wind drifted snow Photo: Matt Primomo

Avalanche Discussion

Avalanche season is here. We’ve received several reports of human-triggered avalanches throughout the cascades, including an accident and related fatality near Crystal Mountain. (See preliminary report below) Overnight snow totals ranged from 5 inches in the eastern parts of the zone to 18 inches closer to the Cascade Crest. With this east-west trend, expect slightly elevated avalanche danger closer to the crest and slightly lower danger moving east. 

This storm brought significant snowfall and strong winds from the west and southwest. We have minimal observations and a lot of uncertainty about snowpack conditions near and above treeline. We do know that the new snow fell on various surfaces, including rain crusts, soft snow, or firmer recently wind deposited snow. This could cause the snowpack to act differently from one slope to the next. Pay attention to signs of instability such as recent avalanches, shooting cracks, and collapsing within the new snow. Quick hand pits and small test slopes can help you identify how well the new snow is bonding to the underlying crust, but remember that there is a lot of variability and the snow on one slope may react differently than a similar slope around the corner. 

At lower elevations, you are unlikely to trigger avalanches in areas with vegetation, tree cover, and talus. There isn’t quite enough snow. However, isolated areas with smooth grassy slopes may produce small avalanches. With the early season snowpack, even small avalanches can have high consequences if you impact rocks, trees, or 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. 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 emergencies.

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