Bulletin d’avalanche

East Slopes North

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

You may be able to trigger small avalanches at upper elevations where the wind drifts new and recent snow.  Look out for pillow-like slabs of snow below ridges. On Monday, just enough new snow and wind will maintain heightened conditions on the highest elevation slopes.

Problèmes avalancheux

  • Wind Slabs

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

    Another shot of light snow and southeasterly wind will maintain wind slab avalanche conditions at the highest elevations. Strong southwest winds built older slabs on Friday in the classic places along exposed ridges, at the tops of chutes, and near the base of cliffs. If you find signs of instability, like cracks shooting through the snow or wind drifts that break easily with a person's weight, stay off of leeward slopes over 35 degrees. Look for visual clues like sharp wind drifts and stiffer snow surfaces. Steer around fresh drifts and stick to lower-angle or wind-sheltered slopes. 

    (12/22/2023)

    Cracks in recently wind transported snow near Harts Pass.

    Photo: Willie Webster

Avalanche Discussion

While new snow accumulations are forecasted to be light, snow and avalanche danger will increase Monday afternoon and overnight. A storm on Friday brought about 4-5" of new snow and stronger winds to the zone. Observers in the Harts Pass and Willow Creek areas noted significant blowing snow, fresh wind features (6-8" deep), and cracks in the new snow.

This new snow fell on a variety of old surfaces, but two seem more prominent. Surface hoar was seen particularly on shaded aspects. On Wednesday, observers on Rainy Pass found it on the surface as well as buried in the top 8" of the snowpack. In steeper, more southerly terrain, a surface crust likely formed. As you travel, take note of where they survived by using small hand pits.

Similarly, older layers of buried surface hoar and the 12/10 crust (below ~6000ft) may be found slightly deeper in the snowpack. The prominent 12/7 atmospheric rain crust continues to be an excellent snowpack marker for tracking variations in the upper snowpack across the terrain.

Régions couvertes