Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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

MODERATE avalanche danger will develop at all elevations as a loose wet avalanche problem forms in response to daytime warming. Timing for travel in avalanche terrain is critical. In wet snow conditions, slopes can switch from stable to unstable in as little as 20 minutes.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    As daytime warming progresses, loose wet avalanches will become possible at all elevations on E-SE-S-SW-W aspects. Further into the daytime hours, this loose wet avalanche problem will spread to NW-N-NE aspects as well. Avalanche size up to D2 is possible (large enough to bury or injure a person). Identify and avoid avalanche terrain in areas where natural or human triggered roller balls are occurring and/or marginally supportable to unsupportable wet snow exists.

    Cloud cover was patchy around the forecast area last night. In locations with above freezing air temperatures overnight, areas of thicker cloud cover will have limited the thickness of snow surface refreeze that formed from radiational cooling. Compare the strength of snow surface refreeze in open areas vs under dense forest canopy. The more discrepancy between the two, the weaker the overall snow surface refreeze in the area of travel. A weaker, thinner snow surface refreeze will give way to unstable wet snow earlier in the day than a stronger, thicker refreeze. Pay close attention to the remaining thickness of surface crust as the day progresses. Once it becomes marginally supportable to unsupportable, the snowpack can quickly become unstable.

Avalanche Discussion

* Recent observations from around the forecast area have shown increasingly well established melt-freeze conditions on E-SE-S-SW-W aspects. The upper snowpack remains transitional on many NW-N-NE aspects, especially at the upper elevations.

* Snowpit tests performed yesterday on Silver Peak (Pole Creek area) in the crown of one of the numerous deep slab avalanches from March 22 indicated that the associated weak layer continues to retain characteristics that allow for propagation. No signs of current deep slab instability were observed.

Regions covered