Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The storm will continue to hammer the area with heavy snow, some rain, and strong winds through the weekend. Expect avalanche activity at all elevations. Travel in, near, or below avalanche terrain is not recommended.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1.5–3

    Large wind slab avalanches occurred yesterday. Expect more wind slab avalanches today as strong southwest winds and new snow pile wind-blown snow onto slopes near ridges, open faces, and gullies. These new wind slabs will form on top of yesterday's still fragile wind slabs on NW-N-NE-E-SE aspects near and above treeline. Some wind slabs may also lurk in below treeline areas or on other aspects due to the strength of the winds. The cornices looming over many slopes will keep growing and could fail far away from their edges. 

    Traveling in, near, or below avalanche terrain is not recommended today. If you do get out, give yourself an even larger buffer to avoid avalanche terrain since blowing snow and poor visibility will make it hard to see what terrain may lurk above or nearby. 

    (3/10/2023)

    One side of the crown of the avalanche triggered by cornice pieces falling on the slope on Andesite Peak.

    Photo: SAC

  • Storm Slabs

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

    As more snow accumulates today, fluctuating temperatures and changing snowfall rates will create weaknesses in the storm snow. Some layers of heavier storm snow will accumulate on top of lighter snow. Unstable storm slabs could form on any steep slope including below treeline slopes and other typically sheltered areas. Storm slab avalanches may start small, but will increase in size and distribution as new snow piles up today. In areas where storm slabs exist over wet snow, they could also entrain some of yesterday's wet snow and produce larger avalanches.  

    Areas that people typically think of as "safe" on a storm day may hold unstable storm slab conditions. Traveling on, near, or below slopes steep enough to avalanche is not recommended. 

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2.5

    With snow levels expected to mostly stay below 6500 ft. today, wet snow instabilities should be more limited in distribution. Still, expect wet loose avalanches on steep slopes in areas where rain falls on snow. Some of these could still entrain enough snow to cause problems for people. The potential for larger wet slab avalanches should decrease as yesterday's wet snow starts to refreeze, but one may still occur in areas where deep rain-soaked snow that has not begun to refreeze exists.

    (3/10/2023)

    Looking up at an avalanche that likely happened Thursday night on Andesite. The debris looked like it had been wet.

    Photo: SAC

Avalanche Discussion

The storm limited observations yesterday, but we did get reports of several natural avalanches hitting Mt. Rose highway and a widespread natural avalanche cycle on Donner Summit, including wind slab and wet slab avalanches. We also saw remotely triggered wind slabs and cornice failures on Andesite Ridge. The storm continues to load the snowpack with rain and heavy snow. Some uncertainty exists about how the deep and complex snowpack will react to this large load. Large loading events can produce unexpected outcomes.

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