Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Ongoing dangerous conditions will continue. You can trigger very large and destructive avalanches at upper elevations where the wind drifts thick slabs of snow. Stick to low-angle slopes and stay well out from under steep overhead terrain.

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.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    You can easily trigger deadly avalanches near and above treeline, and natural avalanches may still be possible. Avoid leeward slopes 35 degrees and steeper, especially where the wind forms thick drifts and pillows. Stay out from under steep, unsupported overhead terrain where natural avalanches could come from above. Consider avoiding any slope where the snow slides easily (or you get sudden test results) on a stout crust 3-4 feet below the surface.

    Avalanches will be largest and easiest to trigger above treeline. You may even find drifts in open areas below treeline. 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.

    (12/8/2021) Long shooting cracks in freshly wind drifted snow. E at 5200ft Photo: Matt Primomo

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    You may be able to trigger avalanches on slopes steeper than 35 degrees where you find enough continuous snow cover to produce avalanches. Look for a hard over soft layering that was formed during Saturday's storm. Quick snowpack tests can be useful to assess if the snow could slide before you commit to steeper terrain.

    (12/9/2021)

    Quick, hand pits are a good way to look for instabilities in the upper snowpack or to check if the recent snow could slide.

    Photo: Adam Butterfield

Avalanche Discussion

Saturday was an active day on Washington Pass. Observers reported natural avalanches up to size D2.5 running throughout the day as temperatures warmed and snow accumulated. Multiple natural avalanches were reported in the Hairpin Valley at the head of Early Winters Creek. These occurred on northeast aspects, likely above treeline, and originated from unsupported, steep slopes. Observers also reported natural avalanches on east northeast aspects that hit Highway 20 between Cutthroat Creek and the hairpin turn.

On Saturday, observers reported that 2.5 feet of snow accumulated since Friday at the Cutthroat Trailhead. Expect another foot of snow to accumulate by the end of Sunday. About 3-4 feet of settled snow has accumulated over the most recent crust (buried in early December).  Observers have reported varied test results and triggered avalanches on this early December crust. The crust seems especially problematic where it's smooth and slick and less so where it has more texture. 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 at low elevation, 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.

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