Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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

Warmer temperatures and strong April sunshine will make wet loose avalanches possible as rapid warming occurs today.  Large cornices along ridgelines will also weaken due to the increased warming temperatures.  The window for supportable snow conditions will be shorter than yesterday-move away from avalanche terrain as the snow surface becomes deep and unsupportable.

Avalanche problems

  • Loose Wet

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

    Warmer overnight temperatures along with clear skies and radiational cooling will provide a more superficial snow surface refreeze than what occurred yesterday.  Warmer temperatures today with full April sunshine will melt the snow surface crusts and form wet snow as rapid warming occurs later this morning.  Wet loose avalanches will become possible as these surface crusts melt away and 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.

    As the snow surface becomes wet, deep, and unsupportable, it's time to change aspects or move away from avalanche terrain.  Roller balls and pinwheels will be signs that the snow surface is losing strength and unstable conditions are present.  Factor into your plan that the window for supportable snow conditions will be shorter this morning than yesterday.

  • Cornices

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

    A warming trend into this weekend could increase the potential for cornice fall.  Large cornices exist along most ridgelines throughout the forecast region.  These cornices could weaken with the warming temperatures and marginal overnight refreeze.  These large blocks could fall downslope and could also trigger wet snow avalanches.

    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 are notoriously difficult to predict. Due to the uncertainty, consider avoiding travel on or below slopes with glide cracks.
  • Over this weekend, the surface crust formed during overnight refreeze is expected to become thinner each night and melt faster each day due to increasingly warmer daytime and nighttime 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