Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Warming temperatures should invigorate a round of  wet avalanches across many sunny slopes. Bigger avalanches can still be triggered in wind drifted terrain or on open slopes that harbor a sensitive weak layer 1-2 ft below the snow surface. Give steep, open terrain some space until we get through this warm-up. 

Problemi valanghivi

  • Loose Wet

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

    Warming temperatures will likely create wet snow instability along solar slopes and potentially more shady aspects if cloud cover increases and promotes ‘greenhousing’. Look for these wet snow avalanches on sunny slopes, especially near steep rocky terrain. While most wet avalanches will likely stay on the small, don’t underestimate wet snow in bigger terrain. These wet avalanches can often grow large as it collects more wet snow as it slides. Rollerballs, pinwheels, snow falling off trees, and deep boot penetrations in wet snow are signs that the surface snow is warming and weakening. 

    (12/9/2024)

    Cliffy south-facing terrain is a common place to see signs of warming or wet avalanche activity. 

    Photo: Toby Swimmer

  • Persistent Slabs

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

    You could trigger 1-2’ thick slabs failing on buried surface hoar, especially where the wind has formed drifts or stiffened the snow surface below ridges. This concerning layer was found around Ahtanum Meadows on Friday, but we suspect this set-up may also exist in other areas around the zone.

    These persistent slabs can release in surprising ways, break wider than expected, and release above or from a distance aways. Snowpack cracking and collapsing or whumpfing are clear signs of unstable conditions. However, a lack of these obvious warning signs doesn't mean you're in the clear either. 

    Approach the mountains with the assumption that this weak layer may exist on many open slopes. The best way to manage this problem is to simply avoid travel on and under slopes open slopes greater than 30 degrees.

    (1/6/2025)

    Dial it back if you notice shooting cracks in wind-drifted snow or in more sheltered terrain. 

    Photo: Joe Dellaporta

Avalanche Discussion

The sun and warmer temperatures might feel nice, but remember, we’re still dealing with a complex, layered upper snowpack and I'm still traveling conservatively because of this. 

The main weak layer we are most concerned about is the buried surface hoar that we found around Ahtanum Meadows this past Friday. This notorious weak layer was responsible for 2 separate rider-triggered avalanches, propagating test results, and long shooting cracks on Friday, January 3rd. While most of the activity was reported around Ahtanum Meadows above 6000 ft, don’t write it off elsewhere. Another skier-triggered avalanche failing at similar depths was also reported around the White Pass area on the same day ( Jan 3rd). 

 

If you get out into the mountains, let us know what you see by submitting a public observation.

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