Bollettino valanghe

West Slopes Central

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 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Heavy snowfall is forecast overnight into Sunday, especially along the Highway 2 corridor. Avalanche danger will be great enough that you should plan on staying in simple, sheltered terrain for the day. Avoid all avalanche terrain if you find deep new snow, strong winds, or fresh natural avalanches.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Look for 1-2 feet of new snow by midday Sunday depending on your location within the forecast zone.  The best time to trigger an avalanche in new snow layers is during or immediately after heavy snowfall. You are more likely to trigger a fresh slab on slopes where the wind built thicker slabs. Given the quantity of new snow in the forecast, it would be wise to assess stability on all aspects instead of just focusing on wind-loaded terrain.

    Tracking new snow depths should be easy with a soft rain crust below the new snow. Use a ski pole or simply dig down with your hand as you gain elevation and change aspects. Look for instability using test slopes, hand shears, and other simple tests. Shooting cracks are a sign you could trigger an avalanche if you head onto a steep slope. When in doubt just stick to simpler, sheltered, lower-angle slopes

    Triggering a small avalanche on a test slope means you will likely find bigger ones on larger slopes

    Photo: Peter Durr

  • Glide Cracks

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2

    Heavy rainfall produced glide avalanches on Saturday in West North and similar avalanche activity is suspected in parts of West Central. Glide avalanches occur when the entire snowpack slides on the ground below. Cooling temperatures and no rain mean there should be fewer of them in the coming days, but they can still release well after it stops raining. The best plan will be to avoid traveling directly under cliffs still holding snow, glide cracks, or slopes with wrinkled snow. Periods of poor visibility could make it difficult to identify hazards in the terrain above you.

    Look for glide cracks and other unstable, sketchy-looking snow features in the terrain above you. (Photo from previous winter).

    Photo: Ben Williamson

Avalanche Discussion

Heavy rainfall was the story Saturday morning until it transitioned to snow at mid-elevations in the early afternoon. Precipitation totals were not off the charts but what was significant was how much of it fell as rain instead of snow. The White Chuck Tripod picked up 6" of new snow by Saturday evening. The Decline Creek Snotel which is a bit lower than White Chuck saw 3" of total precipitation, so count on at least 2" of that falling as rain. Other parts of West Central likely saw even more. One can expect to find a saturated upper snowpack below the new snow. Upper elevations likely have many feet of new snow in addition to what falls Saturday night. Both Snoqualmie and Stevens Pass saw freezing rain earlier in the day.

Reported avalanche activity was limited to glide avalanches in West North with no large wet slab or loose wet avalanches reported. Fresh cracks and other signs of glide were also reported. There were no observations from West Central or even many from anywhere else in the Cascades given poor weather conditions.

 

 

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