Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Heavy wet snow piled up around the East South zone Monday forming an upside-down snowpack. Even though the storm ended, you may still trigger avalanches in the new snow especially on steep convex rolls or in rocky terrain. 

Problèmes avalancheux

  • Storm Slabs

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

    New snow piled up on top of this weekend’s light fluffy powder Monday forming storm slabs in many areas. At nearby Crystal Mt, an avalanche professional reported triggering several shallow slabs failing at the base of this upside-down storm snow. Even though it may be harder to trigger these slides Tuesday, you could still cause avalanches especially on convex slopes and in rocky terrain. Use small slopes and hand pits to investigate and test the new snow. If slopes or tests fail easily, steer around any open areas greater than 35 degrees. While in most locations, these slabs are only 4-6” deep, some spots near the Cascade Crest like Bumping Lake and Hwy 410 may have received 8-10” of snow. In these areas, expect larger and more dangerous avalanches.

    (12/19/2021)

    Using simple hand pits while you travel is a quick way to gain some information about slab potential and the depth of potential weak layers in the upper snowpack. 

    Photo: Dallas Glass

  • Loose Wet

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

    At lower elevations, wet snow and rain fell Monday afternoon and evening. As temperatures continue to warm and very light rain falls, you may encounter a wet and sticky snow surface. This is most likely near the Cascade crest where more rain is expected. Don’t be surprised if you see or trigger small loose wet avalanches. Wet heavy snow and new rollerballs can clue you into the potential for these loose wet slides. Even though they should remain small, don’t let them push you into a creek or over exposed rocks.

    (12/20/2021) Example: Rollerballs near Mt Hood Monday,  along Hwy 35 on a SE aspect 4500ft. Photo: Andrew Kiefer

Avalanche Discussion

Tuesday’s reprieve from recent storms should allow the snowpack to slowly settle and gain strength. As a result, the avalanche danger will decrease slightly. However, a lack of recent observations combined with a relatively shallow and variable early season snowpack still has our attention. Before you step out into larger and more consequential terrain, consider using smaller slopes to gather information. See if what you find lines up with what you expected. If not, dial it back and enjoy lower angle and lower consequence terrain. 

Several storm snow layers exist in the upper snowpack. Rain on Saturday fell to around 4000 ft forming a thin crust in many locations. Even at upper elevations, this storm created a layer of firmer snow. Above this crust/firm snow (12/18), several inches of light dry powder accumulated. Now, this weaker snow is capped by the 4-8” of heavy snow from Monday. The differences between each of these storms are stark and should provide easy to identify snowpack layers.

While some areas of the East South zone still lack enough snow to produce avalanches, other areas have a significant and layered snowpack. We have little information and a lot of uncertainty about snowpack conditions near and above treeline. There is a lot of variability from north to south and east to west throughout the zone, and a more substantial snowpack exists in the northern and western portions. Expect that avalanche danger will vary, throughout the zone. If you head out, let us know what you find by submitting an observation. 

Régions couvertes