Lawinenlagebericht

Eastside Region

Eastern Sierra Avalanche Center
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Lawinengefahr

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

Kernpunkte

New snow and strong winds have created hazardous conditions. Recent avalanches, cracks, and collapsing are signs you should make careful terrain choices and keep a wide safety margin. Weak layers in the snowpack suggest avalanches may be unpredictable and take longer to stabilize than you'd expect.

Lawinenprobleme

  • Wind Slabs

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

    New snow and strong southwest winds over the past 24 hours have built wind slabs in exposed terrain. Drifting should continue, with new slabs forming and recent slabs growing throughout the day. Watch for snow blowing across ridgelines and gullies and loading leeward slopes. Wind slabs can look rounded and textured, or sound hollow under your feet. Recent avalanches, shooting cracks, and collapsing in drifted snow are clear warning signs to dial back your terrain choices and stick to wind-sheltered terrain.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–3

    Large natural and remotely triggered avalanches failed on buried weak layers in the past 48 hours. Field observers in the Virginia Lakes area yesterday reported slope-wide, rumbling collapses below treeline. This matches reports from 9,500-11,000 feet across the forecast area of poor structure and signs of instability, such as shooting cracks and audible collapsing over the past week. New snow has made slabs thicker and potential avalanches larger. Loading from the storm has exacerbated the problem, which will take longer to improve than you might expect.

    Managing persistent slabs is difficult. They may be triggered remotely—from flatter terrain adjacent to steep slopes. Persistent slabs often propagate widely and in unpredictable ways. Shooting cracks and collapses are clear warning signs of the problem. However, feedback is often irregular. The best option is to minimize your exposure to steep terrain on the aspects and elevations with sugary facets buried under stiffer slabs. Be especially cautious of steep start zones overhead.

    (2/5/2025)

    Large remotely triggered persistent slab avalanche near Virginia Lakes on 2/5/25.

  • Storm Slabs

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

    Heavy snowfall rates, extreme winds, and fluctuating temperatures during the storm have created the possibility for instability in the new snow–even in sheltered areas below treeline. You could trigger soft slabs and sluffs of unconsolidated snow. Convex rollovers and confined terrain features like chutes are most concerning. Be cautious on or under steep terrain over 30° today, especially slopes with terrain traps below. Road cuts, gullies, and cliff bands can increase the consequences of even a small avalanche. Snowfall will taper off this morning, and the recent snow will become less sensitive throughout the day.

    (11/25/2024) standing at the base of the test slope which was remote triggered from where i was standing in this photo. West aspect.

Avalanche Discussion

As of this morning, our region has received the lower end of the forecasted precip–except for the Mammoth area, which picked up over 2 inches of new snow water equivalent in less than 24 hours. Snow showers and strong south-southwest winds should continue throughout the morning. Webcams show blowing snow at all elevations. Temperatures rose as snowfall intensified yesterday before dropping after midnight. Showers and winds are forecast to decrease into this afternoon, allowing the storm snow to gradually stabilize. 

Layers of sugary facets and facet-crust combos are buried a foot or more deep in areas north and south of Mammoth. They can be found more than 3 feet deep where winds have drifted the most snow onto shady aspects under cliff bands near the Sierra Crest and on leeward slopes near treeline above about 9,000 feet. Feedback from these persistent weak layers can be inconsistent and a dangerous source of uncertainty. However, I’d bet on 2 facts: new loading has added stress to buried weak layers, and the avalanche hazard will be slower to fall after the storm stops. 

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