Lawinenlagebericht

Eastside Region

Eastern Sierra Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Signs of instability have decreased over the last few days. However, it remains possible to trigger a large avalanche on weak layers at the base of our snowpack near and above treeline. This is especially true in areas where the snowpack is thinner overall and near shallowly buried trigger points. Your best safety strategy for today is to stick to lower-angle slopes without overhead hazards. Expect a quick rise in avalanche hazard tonight as a strong storm system moves in to the region. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    The reactivity of our PWLs varies in relation to region, aspect, and elevation, making them especially hard to manage and predict. You are most likely to trigger a persistent slab avalanche at mid and upper elevations today. Steep, rocky slopes and convex rollovers are areas to approach with caution. Keep in mind that trigger points, such as rocks and trees, may be shallowly buried beneath the snow surface.  Signs of collapsing and wumpfing may clue you into the hazard. However, in areas where the snowpack is deeper, you may not observe any signs of instability until it is too late. Sticking to lower-angle slopes without overhead hazards can help you avoid this problem today. 

    (1/30/2024) Photo: Clancy Nelson

Avalanche Discussion

We expect periods of heavy snow and wind to begin around midnight tonight and continue through Thursday evening. Avalanche hazard will rise quickly. 

What to know about our snowpack before the storm begins: 

A surface melt freeze crust exists almost everywhere at lower elevations and on slopes with sunlight exposure at all elevations. This will make travel both uphill and downhill difficult and will be a cause for concern once we begin to receive new snow. It is not impossible that we may see small areas of wet loose instability today, especially on slopes receiving direct sunlight. As sunlight fades, the crust will lock up again. We are not expecting new snow to bond well to this crust initially. 

It is becoming more unlikely to trigger a large persistent avalanche at lower elevations. Much of our lower elevation terrain has experienced melting and refreezing which has helped begin to heal our PWLs. However, as elevation increases, the surface melt-freeze crust gets thinner, the snowpack gets drier, and the depth hoar gets sharper and larger. The warmth of the past couple of days hasn't had much effect on the deeper layers in our snowpack on more shaded aspects above 9,500'. Our greatest concern lies in the mid to upper elevation band (9,000' - 11,000') where coverage seems to be most consistent, and thick, hard, condensed slabs sit on top of depth hoar and facets that are still well-defined. This is where we have viewed most of our persistent slab avalanches throughout the last week, and where we are expecting the most persistent slab activity in this next storm. 

A similar weak structure is also still present at upper elevations. However, there is less consistent snow coverage at upper elevations as many slopes are scoured. Specific features that are wind-loaded or protected from winds and thus hold consistent snow coverage are where we are focusing our concern. 

 

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