Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 10 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

LOW avalanche danger exists this morning. Some slopes steeper than 35 degrees on the E-SE-S-SW-W aspects may see enough sunshine and warming for the avalanche danger to increase to MODERATE due to the possibility of loose wet avalanches. Loose wet activity may also become possible on some NW-N-NE aspects in near and below treeline terrain if the sun hits those slopes. If more cloud cover persists today, loose wet snow will remain more isolated since less melting will occur.

 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Periods of clearer skies during the night and colder overnight low temperatures should have allowed more snow to refreeze last night than in previous nights. Increased winds, slightly cooler daytime highs, and some scattered cloud cover during the day today should slow down the melting of this overnight refreeze. Still, some areas may see enough sunshine and warmth to melt through last night's refreeze. If this happens the loose wet snow formed by this melting and the loose wet snow lurking below last night's melt-freeze crust will combine to form areas of deep wet loose unsupportable snow on the thawed slopes. Loose wet avalanches could become possible again today. Slopes steeper than 35 degrees on sun-exposed E-SE-S-SW-W aspects in near and below treeline terrain will hold the best potential for loose wet avalanches since they should experience the most warming, but some of the NW-N-NE aspects could also see enough sun for wet snow instabilities to form. Loose wet snow could also form on some isolated above treeline slopes that receive significant sunshine as well. Most of the loose wet snow issues should remain small, but some could still entrain enough snow to cause problems for backcountry travelers especially in areas where they occur near terrain traps like gullies, creeks, and cliffs. If more cloud cover persists over the region, loose wet snow will remain more isolated since less melting will occur.

    Once last night's melt-freeze crust starts to become unsupportable and the wet snow starts to deepen, it becomes unstable very quickly. Some signs that enough loose wet snow has formed for larger wet snow instabilities to occur include sinking into wet snow up to your boot tops and small surface instabilities like roller balls, pinwheels, or point releases. It is best to move to more frozen aspects, onto lower angle slopes away from anything steep, or to switch to an activity that does not involve snow before these clues become widespread and before the snowpack starts becoming unsupportable.

Avalanche Discussion

Yesterday observations on Tamarack Peak showed a mix of supportable and breakable crusts and sticky wet snow on all aspects up to 9800 ft. By mid morning the E aspects had started to soften and by noon they could barely support a skier's weight. The northerly aspects still held mostly supportable crusts at that time. Ski cuts on steep east facing test slopes started to trigger small roller balls and pinwheels around this time as well. Below the surface crusts 10 to 15 inches of wet snow sandwiched between thin crusts existed. 

Regions covered