Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Another superficial snow surface refreeze occurred last night. Wet loose avalanches are possible once the surface crust melts away exposing the deeper wet snow that does not refreeze overnight or when rollerballs or pinwheels are occurring. Exit avalanche terrain before the snow surface becomes unsupportable.

Avalanche problems

  • Loose Wet

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

    For the second night in a row, a strong but still superficial snow surface refreeze occurred overnight at all elevations across the forecast area. As daytime warming progresses, the superficial snow surface refreeze from last night will eventually melt away and expose the deeper residual wet snow that does not refreeze overnight. Wet loose avalanches are possible once the surface crust is mostly or entirely melted away and the deeper wet snow is exposed. Some of these wet loose avalanches could be large enough to cause problems for backcountry travelers, especially on long slopes where a wet loose avalanche will entrain more snow as it travels downhill.

    Once the snow surface starts to become unsupportable it is time to think about avoiding slopes steeper than about 35 degrees. Pinwheels, rollerballs, sinking ankle-deep or more into wet snow when you step off of your equipment, and wet loose avalanches are all signs of unstable wet snow. Exit avalanche terrain before signs of deep or unstable wet snow develop.

    (4/13/2023)

    The upper snowpack structure as seen on yesterday (Apr 13) at 11 am on a SE aspect near 8,000' on Silver Peak, Pole Creek area, CA. Note the superficial crust from overnight refreeze and the deeper wet snow below that does not refreeze overnight.

    Photo: SAC

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    A daily warming trend is expected to begin increasing the likelihood of this avalanche problem today through Sunday. Large to massive blocks of snow falling off of overhung cornice sections along ridgetops could cause problems on their own or trigger wet snow avalanches on the slopes below.

    Most cornice fall accidents occur during ridgetop travel and take the party involved by surprise. Stay well back from cornice edges, keeping exposed rocks or trees between you and the cornice edge. Consider avoiding travel on slopes below cornices.

    (4/12/2023)

    A recent cornice collapse along the ridgetop west of Rose Knob Peak, NV.

    Photo: SAC

Avalanche Discussion

  • Some glide cracks have formed on steep slopes in rocky areas. Like cornice fall events, the exact timing of glide crack avalanches is notoriously difficult to predict. Due to the uncertainty, consider avoiding travel on or below slopes with glide cracks.
  • Over the next several days, the surface crust formed during overnight refreeze is expected to become thinner each night and melt faster each day due to increasingly warmer daytime air temperatures. The window of time for travel in avalanche terrain before wet snow avalanche problems become a concern will get shorter each day. For travel in avalanche terrain, plan to start early and end early.

Regions covered