Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 8 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

LOW avalanche danger exists at all elevations today. Triggering a deep slab has become unlikely on a regional scale. Unlikely does not mean impossible and a deep slab problem could still lurk on some isolated terrain features. Some isolated loose wet issues could occur today if the forecast area receives more sun or warmer temperatures than expected.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    Triggering a deep slab avalanche has become unlikely for the vast majority of the forecast area due to the snow above the persistent weak layer becoming much stronger and the persistent weak layer adjusting to the load above it. Unlikely does NOT mean impossible and some isolated terrain features where the weak layer remains closer to the surface may still be suspect. These isolated areas could include places where a shallower overall snowpack exists or areas where trigger points like rocks, cliffy areas, single trees, stumps, etc exist on slopes with a deeper snowpack. On these isolated slopes, several tracks could exist before a person finds the trigger point that would release the entire slope. This unlikely but not impossible problem would still have severe consequences.

    Even though deep slabs have become unlikely on a regional scale enough uncertainty exists concerning them that making travel plans to avoid those isolated areas where this problem could linger still represents a prudent choice. Lower angle sheltered northerly aspects continue to offer good recreation conditions.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    Cloud cover, winds, and slightly cooler daytime highs should keep loose wet instabilities unlikely today. Some small roller balls, pinwheels, or loose wet point releases could still become possible if the sun does come out during the day or if temperatures climb higher than expected.

Avalanche Discussion

* Yesterday on Mt. Lola, snowpit observations found the persistent weak layer about 1.5 m below the surface, but it had become much denser and more cohesive and no longer looked like facetted snow. Snowpit tests and observations from around the forecast area since Saturday have shown that the facet layer buried 1 to 1.5 m deep in the snowpack has become increasingly difficult to trigger. Some of the data also still indicated that if it does break the resulting fracture could still propagate along the persistent weak layer. Another loading event could still reactivate this layer.

* Some wind transport and wind-loading was observed on Castle Peak yesterday, but ski cuts and cornice cuts did not trigger any signs of instability.

* Wet sticky surface snow existed on all aspects up to 8000 ft. on Mt. Lola yesterday and up to 7800 ft. on Rubicon. Wet surface snow also existed on southerly aspects of Castle Peak by the afternoon. 

* Sheltered true north aspects above 7800-8000 ft. still held cold soft snow on Castle Peak, Rubicon, and Mt. Lola. In more exposed areas variable snow surface conditions ranging from firm wind affected snow to soft snow existed.

Regions covered