Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

New snow and wind will make avalanches likely today on open slopes, near ridges, or in gullies where wind-blown snow has piled up. New snow may also sluff off of the frozen crust below it on steep slopes in sheltered areas. Watch out for signs of unstable snow like recent avalanches, blowing snow, cracking snow, and sluffs of snow. Move to gentler terrain if signs of unstable snow exist or if you have any doubt about the snow's stability. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Strong winds and new snow have piled wind-drifted snow onto the leeward aspects. These new wind slabs will continue to grow as the storm continues. Firm crusts exist below the wind slabs and triggering a wind slab avalanche will be likely today. Expect fragile wind slabs on open slopes, near ridges, gullies, and other wind-exposed terrain features. The largest wind slabs will exist near and above treeline, but wind slabs may also exist in below treeline areas due to the strength of the winds. Fragile cornices may also lurk above many of these slopes. Areas along the Sierra Crest where more snow accumulates will have larger wind slabs. Smaller wind slabs will exist in areas east of the crest where less snow has fallen.

    Blowing snow, cornices above a slope, snow drifts, and wind-created surface textures all indicate the presence of wind slabs. Route plans that give wind slabs a wide berth can help avoid getting caught in a wind slab avalanche. This planning will also steer your group into more sheltered terrain where less wind-affected snow will likely exist.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Decreasing temperatures during this storm should mean lighter snow sits on top of heavier snow (right-side up), but firm crusts also exist below the new snow. Poor bonding between the new snow and the crust could allow the new snow to slide off the crust as a sluff of loose snow. That being said, some soft slabs of storm snow may also be possible in areas that have the most new snow along the Sierra Crest.

    Loose snow avalanches entrain more snow on long, steep slopes. In some places, they may gather enough snow to knock a person over or push them into areas that magnify the consequences of small avalanches. Signs that the new snow could slide off the crust or on storm snow weaknesses include recent snow sluffs, spindrift, or feeling the new snow sliding off the crust as you travel. If any signs of instability exist, you can move to terrain less steep than 30° to reduce your exposure and still enjoy the snow. 

Avalanche Discussion

This storm has focused its precipitation on and west of the Sierra Crest, where the weak layers have gained strength, with significantly less snow in areas east of the crest where weak layers remain buried. It is unlikely that the limited new snow amounts east of the crest will reawaken old, weak layers of faceted, sugary snow that still lurk in the lower half of the snowpack where a shallow snowpack exists on the east side of the forecast area. Future storms that impact the east side of the forecast area may still be able to reactivate these weak layers.

Regions covered