Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Monday will be a notch warmer, which will set the stage for wet avalanches on steep slopes that receive sun. Move to colder slopes once you notice signs of warming, like rollerballs and pinwheels, or if you're sinking past your ankles in wet, sloppy snow. 

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Sun and rising temperatures will keep the threat of wet avalanches in the forecast. You can anticipate this problem by considering your aspect vs. timing of when you might be on any given slope. Look for signs of instability, like small rollers falling out of trees or small fan shaped slides. Feel for moistening snow surfaces on slopes in the sun. You can use test slopes to see how any area might react. These slides should remain small, but may be able to entrain more than you'd think, especially in larger terrain features. Wet loose avalanches could be precursors to larger wet avalanches, so move to less steep terrain out of the sun if you notice these point releases. 

    Large cornices exist across many ridgelines and alpine features across the zone. They often fail much farther back than expected. During these warm sunny periods, they can become weaker and easier to trigger. Give these some space, especially with the warming trend

    (3/31/2024)

    Rollerballs and wet loose avalanches off steep rocky terrain in the Chiwakum Mountains. 

    Photo: Katie Warren

Avalanche Discussion

Preliminary Report: NWAC is saddened to report an avalanche fatality as a result of a cornice fall on Mount St. Helens. On Friday, March 29, 2024, a snowboarder summited the peak. While standing near the top, hetriggered a cornice and fell into the crater triggering a large slab avalanche on the slope below. NWAC is working with Skamania Co Sheriff’s office and SAR to compile a report. Our deepest condolences to the family, friends, and community.

Discussion:

Monday will be warmer than previous days. By the afternoon, look for freezing levels to climb over 11,000 ft. Despite the warm temperatures, you may still be able to find dry snow along northerly aspects and some wind-loaded pockets in these areas. Use caution around wind-drifted terrain and assess for instability before committing to bigger terrain. 

Observers have taken advantage of the nice weather to push to higher elevations across the zone. One observer in the Stuart Range found good skiing at upper elevations but also reported wet surfaces as the day progressed and triggered a small wet loose avalanche on a solar slope. 

On both Friday and Saturday, backcountry skiers triggered small D1 avalanches in the Mission Peak area. These avalanches broke 9-12 inches and occurred on east aspects at approximately 5800 ft. You can check out their observations here and here. Around the same area on Friday, an NWAC forecaster found a layer of buried surface hoar within the recent snow. We're still figuring out how widespread surface hoar is - but it's worth noting if you travel in the Blewett Pass and Mission Ridge backcountry. 

Even though we aren't forecasting persistent slabs, the weak layer is still there. It's been a few weeks since we've seen an avalanche on the facets over the Early February Crust. While not impossible, it is very unlikely you'd see an avalanche on this deeper layer. It would likely take a bigger trigger in higher elevation shaded terrain to result in a slide. If you're traveling in these areas, factor that into your uncertainty when discussing terrain. 

At lower elevations, the snowpack is thin and even sometimes discontinuous. Even though these snow down low is wet and weak, this helps all but eliminate the avalanche risk.

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

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