Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Assess conditions carefully as you ascend in elevation. You could stumble into a dangerous combination of wind slab over facets and crust in higher alpine terrain near the crest. Whumphing collapses and long shooting cracks are signs of instability you might find, and should be heeded.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    You could trigger surprising avalanches on leeward slopes at upper elevations where very strong winds have formed slabs on open, exposed slopes. Leeward terrain for the recent winds will be mainly on N-E-SE facing terrain, but you could find pockets of slab on all aspects. Look for signs such as wind stiffened snow, blowing snow, shooting cracks, and deeper drifts on leeward slopes. Steer around recent drifts and slabs on slopes steeper than 35 degrees. Use extra caution because these slabs may be resting on weak facets over a crust.

    If you see shooting cracks or get whumphing collapses, stick to slopes 30 degrees or less and put a large buffer of terrain between you and avalanche prone slopes. Monitor the bond between the recent storm snow and older crust layers. If you find weaker faceted grains on a crust or crumbly sugary snow over a crust, then all you need is a cohesive slab on a steep slope and it could avalanche.

     

    (2/1/2022)

    Shooting crack on a wind-loaded feature at 5,800ft in the upper Salmon la Sac drainage.

    Photo: Ryan Minton

Avalanche Discussion

Recent storm totals are greatest near the crest. One observer reported around 16" of new snow at 5,000ft in the upper Salmon la Sac drainage on Tuesday. Katie Warren found 12" above Lake Wenatchee. Both observers found the storm snow was fairly well-bonded to older crust layers, but these observations were not from the most suspicious slopes to hold persistent weak layers- NW-NE aspects above 6,000ft or so. Drew found this crust/facet combo out at Holden, but there wasn't enough snow on it to be problematic, yet. 

In the eastern portion of the zone new snow amounts are minimal and avalanche danger is isolated to shallow windslabs near leeward sides of ridges. Closer to the Cascade Crest in the upper drainages above Cle Elum, Leavenworth, Lake Wenatchee and Entiat you may find different conditions. Prior to the storm, observers found near-surface facets on a variety of shaded, northerly slopes and surface hoar on similar aspects below 4,700ft. Approach steep slopes with an assessment mindset and be ready to move to lower-angled terrain if you find reactive avalanche conditions. 

Regioni coperte