Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

New snow is beginning to settle, and avalanches are less likely. However, you may still be able to trigger avalanches on steep terrain features at most elevations, especially on northern aspects and where the wind has drifted snow into deeper drifts. Avalanches could run on weak snow near the ground; this is more likely in areas around Mission Ridge and Blewett Pass. Assessing conditions before stepping out into bigger, steeper terrain will be essential. Be particularly suspect of steep open terrain near ridges or steep rolls in sheltered terrain. 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    Multiple avalanches running on weak snow near the ground occurred near Mission Ridge. These avalanches were triggered during control work and by skiers in backcountry terrain and were up to 3 feet deep in places. These weak snow layers take time to adjust to significant changes like the 12-24inches of snow that fell over the weekend. While the likelihood of triggering these large avalanches is decreasing, assessing the snowpack is essential before committing to steep slopes. Steep, northerly aspects are the most suspect location for these deeply buried weak layers to exist. Be particularly suspect of steep open terrain below ridges, steep rolls in the middle of slopes, and near rocks or cliffs where you are more likely to trigger these avalanches.Dig down and identify sugary, faceted layers or feathery surface hoar layers buried in the snowpack. Stay on lower angle slopes if you find the overlaying snow slides easily on these layers, experience whumping collapses, or observe cracks shooting out from your equipment. 

    (12/10/2022)

    3ft deep persistent slab avalanche in a heavily wind loaded area at Mission Ridge

    Photo: Drew Carlton

Avalanche Discussion

We are on the tail end of a stormy period and transitioning into a sunny and dry weather pattern. A significant upslope storm affected the East Central Zone Friday night into Saturday. Storm totals fell into a fairly wide range, from 0.5" of SWE to 1.4" of SWE. Measured snowfall amounts ranged from 10" (Sasse Ridge) to 20" (Leavenworth). Sunday saw clearing skies and tapering precipitation, with observations of new snow becoming heavy and roller balls on sunny slopes. 

On Saturday, three large avalanches were reported from Mission Ridge, with ~3ft deep crowns. Most avalanches on this deeply buried weak layer have occurred near and around Mission Ridge and Blewett Pass. However, a similar snowpack structure exists in many places throughout the East Central Zone. Therefore, we are uncertain if there are other areas within East Central where these layers are more susceptible to producing avalanches. 

Last week, a clear, sunny day with a cold clear night produced surface hoar. This surface hoar may now be buried and preserved on open, wind-sheltered slopes. 

With a sunny day in the forecast tomorrow, you may see roller balls or wet snow sliding off steep terrain near rocks or cliffs.

If you are out and about in the mountains, you can help us by submitting an observation. 

Régions couvertes