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

Warm sunny weather today will make short work of last night's refreeze and avalanches of loose wet snow will be possible as soon as the surface crust melts. Cornice failures also remain possible today. MODERATE avalanche danger will quickly form at all elevations.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Despite the warm overnight temperatures, a thin refrozen surface crust should have formed during the night under mostly clear skies. Strong April sun and warm weather will quickly melt through this crust and expose deep wet snow. The E-SE-S aspects should melt first followed by all other aspects as the day warms up. Loose wet avalanches will become possible on steep slopes once the surface crust melts. Some of these could entrain enough snow to bury or injure a person especially on large steep slopes or in areas where terrain traps exist. 

    Recreating on on lower angle terrain without steep slopes above once the snow becomes soft and wet represents one way to avoid loose wet avalanche problems. Starting early to try and catch the short window of supportable snow and finishing before the snow becomes deep and wet is another. 

    Photo: Loose wet avalanche on Jobs that likely occurred on 4/25 or 4/26.

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Cornices that exist along many ridgelines will continue to weaken in today's warm sunny weather. Large pieces could break off of these overhanging waves of snow as they melt. These blocks of snow could injure a person on their own and may entrain more wet snow when they impact the slopes below them.

    Cornices often break farther back from their edges than expected or at unexpected times. Staying far away from the edges of cornices and not traveling underneath cornices can help avoid this problem.

    Photo: Large cornices looming above a slope on 4/26.

Avalanche Discussion

* Spring melt-freeze conditions exist on all aspects across the forecast area.

* Observers reported a decent refreeze above 8000 ft yesterday on Jobs Peak (south of Heavenly) and in the Forestdale Divide area (near Carson Pass). In these areas, the snow remained supportable until ~11 am on sunny slopes. On Rubicon Peak (West Shore) less refreeze had occurred and the snow was barely supportable by 10:30 am on E aspects. Below 8000 ft unsupportable punchy wet snow existed in all of these areas by 11 am. 

* A snowmobile brake check on a steep slope with buried rocks in the Forestdale Divide area (near Carson Pass) resulted in a small wet loose pile that ran downhill about 100ft around noon yesterday.

* Debris from recent loose wet avalanches that likely occurred on 4/25 or 4/26 existed in the NE gully of Jobs Peak (South of Heavenly). 

Regions covered