Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

An uncertain snowpack combined with significant warming is a good reason to increase your safety margins. Wet surface snow and the possibility of triggering a large avalanche mean you should be cautious around steep terrain with variable snow depth and buried weak layers. As the warming trend continues, avoid spending time in the runouts of large avalanche paths at upper elevations.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Persistent slab avalanches can be triggered from a distance on flatter terrain adjacent to, or below steep slopes. They often propagate long distances, connecting terrain features that typically contain surface instabilities such as storm or wind slabs. If triggered, the resulting avalanche could break with little warning, involving the full depth of the snowpack.  Where weak layers are buried more than three feet below the snow surface signs of instability may be less obvious, but the possibility of human-triggered avalanches still exists. Cautious route selection remains the most important strategy to manage this problem. Choosing travel routes with lower slope angles and no overhead hazard is a good way to limit your exposure to these types of avalanches.

    (1/25/2024)

    Crown lines in the upper start zones of Bloody Couloir. Released mid-day on 1/24/24. (North aspect, 12,400' to 12,000')

    Photo: Everett Phillips

  • Loose Wet

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

    Warm air temperatures and cloud cover caused melting at the snow surface below 10,000' on most aspects yesterday. A poor refreeze at all elevations last night and rising temperatures mean that wet snow instability is a concern today. Rollerballs and wet surface snow on steep slopes are indications that wet loose avalanches are becoming a hazard in nearby terrain. Rocky chutes, vegetated slopes, and areas with shallow snow cover will be the most concerning.  If the snow gets wet at higher elevations, that's a sign that the likelihood of wet loose avalanches is greater than expected. The best strategy is to avoid traveling in terrain traps under steep warming snow slopes and to make your own localized assessments to determine the extent of hazard in your area.

Avalanche Discussion

Recent avalanche activity: On Wednesday 1/24/24 a few inches of snowfall combined with blowing snow brought on a round avalanche activity involving persistent weak layers. Multiple large to very large avalanches released naturally in north and northeast-facing alpine terrain on Bloody Mountain, Mammoth Crest, Mt. Gibbs, Mt. Wood, and in the Mount Dana area. No natural or human-triggered avalanches have been reported in the past two days.

Snowpack discussion: On most aspects and at all elevations, a layer of depth hoar and basal facets that formed in late Nov. and early Dec. is buried between 2 and 3.5 feet below the snow surface under a strong mid-pack slab. Signs of instability have become less obvious where basal weak layers are buried more than 3 feet deep. However, variations in snow depth between drainages and within slopes continue to make the likelihood of persistent slab avalanches difficult to assess. 

Warming trend: Freezing levels have climbed into the highest elevation band and are expected to increase over the next 48 hours. Warming will change the snowpack structure at all elevations in the coming days. Below 9500' the basal weak layers have been exposed to a warm-up earlier this season. Above 10,000' persistent weak layers have not previously adjusted to above-freezing temperatures and will be exposed to warming for the first time. The timing and severity of the rising danger associated with the warming trend are a significant source of uncertainty in today's forecast and the outlook for tomorrow. 

Forecasting persistent slab avalanche activity is inherently uncertain. This problem exists in most areas where there is enough snow for riding. The most effective risk management strategy for this hazard is to be patient and avoid steep terrain.

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