Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 10 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Areas of MODERATE avalanche danger linger near and above treeline due to old wind slabs. Below treeline, LOW avalanche danger exists. Avalanche activity has been reported in isolated areas each of the past two days.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Old wind slabs may remain unstable in isolated areas on all aspects above treeline and on NW-N-NE-E-SE aspects near treeline. Evidence of instability gathered through informal observations and snowpit data has been limited at best, yet isolated avalanche activity continues to occur. The failure layer has not been confirmed in any of the avalanches that occurred over the past two days. Weak faceted snow that formed in the upper snowpack since Dec 15 has been noted in some areas and may be playing a role in the ongoing instability.

    Take home point: Avalanches continue to occur in isolated areas. Don't expect signs of instability to present readily, but rather remain elusive. Any additional avalanches that occur will likely take backcountry travelers by surprise. For this reason, don't allow travel partners to get sloppy by grouping up in runout zones, too close to the slopes above or by relying on marginal islands of safety for protection.

Avalanche Discussion

An avalanche was reported the have occurred yesterday during the late morning hours on Mount Houghton (Mount Rose area) in a SE aspect gully known for cross loading by both SW and NE winds. This avalanche overran previous tracks, much like the avalanche reported on Sunday.

Observations made and received yesterday from Castle Peak (Donner Summit area), Steven's Peak (Carson Pass area), and on Relay and Tamarack Peaks (Mount Rose area), showed that signs of instability were very limited. Occasionally but not always, snowpit tests have pointed to some potential instability in the upper portion of the snowpack. Data is limited, but newly formed facets have been observed on top of the Dec 15 rain crust in some but not all areas. In the highest elevation areas (above ~9,700') where the Dec 15 rain crust is absent, newly formed facets have been observed within the lower portion of the recent storm snow.

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