Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Another storm bringing snow and wind to the eastern slopes of the Cascades will create dangerous avalanche conditions in alpine terrain. You can easily trigger avalanches in wind-drifted snow at upper elevations. Consider wind-sheltered slopes and avoid steep ridgeline terrain where you find pillow-like drifts of snow.

Problèmes avalancheux

  • Wind Slabs

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

    Snow accumulations of 8-10 inches may be possible overnight as a storm favoring the eastern slopes of the Cascades moves into the region. Moderate winds will easily drift new snow to lee slopes near ridgelines and form fresh, sensitive wind slabs. With minimal direct observations, there is significant uncertainty about what types of surfaces these wind slabs will form over. After a cold, clear night on Tuesday, there is potential for slabs to form over weaker surfaces or slick melt-freeze crusts. Visual clues such as textured surfaces, cornices, and pillow-like drifts of snow can help you identify and avoid fresh wind slabs. Avoid steep terrain near ridges in alpine terrain, and consider sticking to wind-sheltered areas or low-angle routes at lower elevations. If you see signs of instability such as shooting cracks or feel the snowpack collapse beneath you, move to more conservative terrain with slopes less than 35 degrees.With the potential for new snow to accumulate on weak snow surfaces or crusts, you may find small storm slabs even in wind-sheltered locations. If you find more than 6 inches of new snow, use hand pits and test slopes to observe how the snow reacts before committing to steep terrain. 

    (12/16/2021)

    Blowing snow and fresh wind drifts in the East Central Zone.

    Photo: Kyle Hornor

Avalanche Discussion

April seems to be dishing out storms favoring the eastern slopes of the Cascades, and another round of snow is likely in store for the East Central zone. A stormy evening and night, moderate snowfall will eventually give way to lighter showers and the potential for sun breaks in the afternoon. The intense spring sun can quickly make wet loose avalanches possible, even with short sun breaks, and fresh, dry snow is particularly susceptible to warming. So if you find yourself on slopes in direct sun with snow surfaces becoming moist or rollerballs forming, it will be best to move to lower angle or shady terrain. Even a small wet loose avalanche could be consequential if it knocks you off your feet and carries you into trees, rocks, over cliffs, or buries you in confined terrain.

Forecasting these tricky spring weather patterns can be difficult, creating uncertainty in both the weather and avalanche forecasts. However, it is not unusual for spring weather to be challenging, and you should plan for some of this uncertainty when you head out into the mountains. Keep your senses tuned into the snow and look for signs of deteriorating snow stability such as recent avalanches, wet snow surfaces, actively blowing snow, and heavy snowfall.

Over the last week and a half, 2-4 feet of snow has accumulated in the East Central. Sunny weather on Sunday formed melt-freeze crusts on southern aspects that now have 3-10inches of snow over them. Rain at elevations below 4000ft has created a stout crust that may make travel challenging. The crust buried on 4/8 is now under 3-5 feet of snow. There is uncertainty around these interfaces with limited observations and challenging access, so it will be worth digging down to investigate before committing to steep terrain. If you are out enjoying the long days in the mountains, please help us finish the season strong and submit an observation to the platform. 

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