Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Mon
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

Wet avalanches should still be your main focus, with another warm, sunny day in store for Sunday. Chunks of snow falling from ridges or cliffs and triggering avalanches in unsupportable wet snow are all possible. Give overhead cornices and cliffs holding snow some extra space, and consider moving to lower angle terrain if you're sinking deeply into wet snow.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1

    It seems appropriate to have a wet avalanche problem for the end of our forecasting season. Most avalanches will likely involve old snow shedding from steep rocky terrain and entraining additional snow as they move downhill. However, as the prolonged warm temperatures weaken the snow deeper into the snowpack, you could also trigger wet loose avalanches. While these avalanches are typically predictable, they can still grab your feet or slide from above, catching you off guard. Another common spring hazard is cornice falls. These large, heavy, overhanging chunks of snow are a hazard on their own, but they could also start a wet loose avalanche on the slopes below. Stay aware of these overhead hazards and if you begin to sink into wet snow deeper than your calf, it might be time to move to lower angle or shadier slopes. 

    (3/31/2021) 

    An example of a wet loose avalanche that started from a small cornice fall.

    Photo: Matt Primomo

Avalanche Discussion

While a clear night might help surfaces refreeze overnight, ambient temperatures will remain well above 32 degrees. Monitor the surface conditions when you start your day. A solid refreeze of surfaces is a good sign for snow stability, but a thin or non-existent crust could mean wet avalanches could be possible much sooner in the day. 

Springtime mountain travel requires carefully monitoring snow surface conditions and planning routes that are more likely to put you on shady slopes in the late afternoon. While it can be a straightforward problem to understand and manage, conditions can change rapidly and catch you in the wrong spot at the wrong time. Ensure you have alternate route plans or safe exits if you plan to be out late into the afternoon. 

Lower elevations and southerly aspects are melting out quickly this year. On Saturday, NWAC forecasters near White Pass saw thin coverage on most aspects in the East South. Southern slopes have inconsistent snow coverage until about 6000ft. While northern aspects are fairing a bit better, there still isn't consistent snow until between 4500 and 5000ft. Be prepared for long and challenging approaches on roads and summer trails. Open creeks, exposed rocks, and slide-for-life conditions can easily exacerbate the consequence of a small avalanche. There are still plenty of options for winter recreation at upper elevations; you just have to get there!

This is the last avalanche forecast for the 23/24 season. NWAC will continue issuing mountain weather forecasts each afternoon at 2:30 pm through April 28. We'd like to thank each of you for reading and using these forecasts to make informed, safe decisions and for contributing to your community by submitting observations. Please continue to help support your backcountry friends by letting others know what you find in the mountains. Have a wonderful spring and summer!

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