Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Very large avalanches are unlikely, but not impossible. Expect mild and cloudy conditions for Sunday. Check snow surfaces to see how well they froze overnight.

Problèmes avalancheux

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    3

    While it's been almost 2 weeks since the last known deep slab, the consequences of these avalanches could still be serious. Avalanches at the end of February were 3-8ft deep and often covered entire terrain features. The most suspect areas are unsupported slopes, higher elevation, shaded aspects, and slopes that received significant wind-loading. Steep, sunny slopes may be of less concern due to a thick melt-freeze crust near the surface.  A large cornice fall or a major warming event could be the trigger needed for a deep slab avalanche. 

    Observers continue to find sudden and propagating test results on a layer of faceted grains above or within the mid-January crust. Be intentional about where and how you travel, and consider the low likelihood but high consequences of an avalanche. Before venturing into large avalanche paths ask yourself if you're willing to take the risk of being caught in a very large avalanche.

    (3/3/2021) This avalanche likely occurred around February 26. ENE aspect at 7,300ft west of Cashmere Mountain.

Avalanche Discussion

Many solar aspects have well-developed crusts. We're at the end of a prolonged warm period, and wet avalanches may still be possible if snow surfaces don't freeze overnight. Check snow surfaces to see how well they've frozen. Be aware of any overhead or nearby cornices, as they could fall. There have been observations from nearby zones of falling cornices in the past week. 

The last observation of a deep slab avalanche was March 1, however, the mid-January weak layer can still be found in many areas. There were reports on Thursday and Friday in the Icicle drainage that showed consistent results indicating propagation on north and southeast aspects near and below treeline. We currently have a wide range of conditions between mountains near the Cascade Crest and further east. The slab that sits over this weak layer ranges dramatically from around 8ft thick near the crest to less than 3ft in the eastern Wenatchee Mountains. 

Numerous deep and very wide avalanches (Many D3-3.5's, some size D4's)  ran between February 21st and March 1st in the mountains near the crest, and some deeper slabs were reported from the Wenatchee Range. In the northern end of the zone, near Holden, the mid-January weak layer doesn't appear to be a concern anymore.

Régions couvertes