Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Morning update 0800:   Increased danger rating to Considerable for below treeline due to higher precipitation amounts than originally expected. 

You can trigger a slab avalanche on any slope greater than 35 degrees at mid and upper elevations. Use small test slopes and hand pits to check the bond of the old/new snow and see if it fails. Many early season obstacles are still lingering across the east-south, so even a small avalanche can still have high consequences. 

Problèmes avalancheux

  • Storm Slabs

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

    Significant new snow will create reactive slabs at all elevations. Top-heavy slabs of new snow may be primed for a human trigger on slopes greater than 35 degrees.  Expect these slabs to be most reactive in the early morning hours corresponding with the heaviest precipitation.  Larger slabs will develop at higher elevations where winds will deposit new snow into fresh drifts.  Use hand pits or test slopes to evaluate how the new snow bonds to the old surface. Steer around slopes if you observe test slopes sliding easily, cracking within the new snow, or hard over soft layering.

Avalanche Discussion

 

Leading up to this storm, the east-south zone had some cold and clear nights that may have developed weak surface snow ( surface hoar and near-surface facets).  Adjacent zones to the north, south, and west have observed this weak surface snow. So it's possible that its distribution extends into the east-south.  A thin gray line will often indicate a layer of buried surface hoar. So if you see this thin gray line, avoid slopes on similar aspects and elevations 

Higher elevation areas such as Mt. Aix and Darland Mtn have a deeper and more layered snowpack.  In these locations look for weak, sugary snow that sits adjacent to a crust buried in late November.  There have been limited observations of recent avalanche activity on this layer in this zone.  However, our neighbors to the north in the east-central zone have observed avalanche activity on this 11/22 layer and are still receiving propagating results in test pits.  Similarly, Crystal Mt Ski Patrol (near the border with the East South), triggered several avalanches with explosives on these older snow layers.  The combination of limited observations and knowing adjacent zones are dealing with a poor snowpack structure, should make you take a step back and closely evaluate shaded slopes that may harbor this weak snow. 

The snowpack around the East South zone is still relatively thin.  Expect open creeks, holes around rocks, and shallowly buried brush to make travel much trickier and more dangerous. Give yourself a little extra time to navigate around these obstacles.  

If you get out into the East-South Zone tell us what you see by submitting an observation on our public observation platform!  These observations play an integral role in producing a quality avalanche forecast, but also help the greater backcountry community.

Régions couvertes