Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

It's becoming more difficult for you to trigger surprising avalanches that break 2-4 ft deep, but unfortunately, the consequence remains the same. So carefully choose your travel routes to avoid large, steep open slopes and fresh wind-loaded pockets. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wind slabs are becoming more difficult to trigger as time moves on. However, we're expecting a bump in east winds, which may redistribute snow onto uncommon aspects. This loading pattern will often surprise people since slabs will build on west aspects or across terrain features. So don't let your guard down as you change aspects in the coming days. 

    The consequence of triggering a wind slab in the wrong spot could be dire if it steps down into weak snow 2-4 ft below the snow surface. You'll want to carefully assess and look for signs of recent loading as you travel. You can use visual clues like blowing snow or sharp drifts to help you identify problematic slopes. These wind slabs will often lurk beneath cornices, under rock and cliff bands, and on rollovers in exposed areas. Shooting cracks or audible whumphs are obvious signs that you found an unstable slab. The best strategy will be to seek out more sheltered slopes and avoid steep, open areas that harbor a weak snowpack. 

    Use visual clues like blowing snow to help you identify wind-loaded aspects. 

    Photo: Joe Dellaporta

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    You can trigger large avalanches on various weak layers that now sit 2-4 ft below the snow surface. This structure is widespread throughout the zone and in many parts of the region. A layer of buried surface hoar from January 2nd sits an inch or two above a crust from December 30. These avalanches can act in surprising ways, and be triggered from adjacent slopes. Since these avalanches can really pack a punch, you’ll want to increase your margins and seek out more sheltered slopes less than 30 degrees.

    (1/10/2024)

    Backcountry travelers near Lake Wenatchee remotely triggered this avalanche from a low angle adjacent slope. This avalanche ran on weak, facted snow over the Solstice Crust.

    Photo: Pat Riffie

Avalanche Discussion

Sunday was a cold day across the eastern mountains, but observers still reported a few notable observations. First off, backcountry travelers in the Blewett Pass area reported multiple whumphing collapses while skinning. Another observer on Mt Cashmere reported a fresh batch of surface hoar on sheltered slopes which will be worth tracking with more active weather on the horizon. 

Over 3ft of snow has fallen in most areas of East Central this week, with around 1.5ft in the easternmost portion of the zone. NWAC forecasters went to the lower slopes of Cashmere on Saturday and found small faceted grains over a crust above 3,000ft. This is the classic weak structure that can result in a persistent slab avalanche. Another NWAC forecaster visited the Salmon La Sac area on Wednesday. At 4600ft, she found around 70cm of new snow with a thin melt-freeze crust from a brief warmup midstorm buried 45cm down. This new melt-freeze crust showed potential for propagation in a snowpack test. Weak snow beneath the Solstice Crust also showed propagation in these test results. 

If you get out, let us know what you see by submitting a public observation!

 

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