Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Sun and warmer weather will allow sluffs of wet loose snow to become possible on steep slopes. In areas where more snow accumulated during the recent storm, large wet loose avalanches could occur. In areas with less storm snow or where the storm snow has already melted away, wet snow instabilities should remain smaller. Avalanche danger will start out LOW this morning while the snow surface remains frozen and increase to MODERATE once the refreeze melts and wet snow develops.

Avalanche problems

  • Loose Wet

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

    The strong refreeze and today's afternoon cloud cover should prevent the older more established melt/freeze snow below the recent storm snow from getting too wet. However, sun and warmer temperatures today will still cause enough warming in the recent snow for sluffs of wet loose snow to become possible on steep slopes. In the places where only a few inches of recent snow exists, these wet loose avalanches should remain small. In places like the Mt. Rose area where more snow accumulated during the storm, the wet loose avalanches could be large enough to injure or even bury backcountry travelers. Wet loose avalanches would entrain all of the recent snow. Long steep slopes can produce larger wet loose avalanchesTerrain traps like gullies, creekbeds, cliffs, etc. can also cause problems since they can make small avalanches have bigger consequences. If the afternoon cloud cover actually produces precipitation, wet snow instabilities would be more widespread in areas that receive rain or new heavy wet snow.

    Signs of wet snow instability include pinwheels, rollerballs, wet sticky snow, and sluffs of wet loose snow. As soon as any signs of wet snow instabilities exist, it is time to find an aspect where the snow remains cold or move to low angle slopes without steep slopes above.

    (4/14/2021) Snowboarder triggered wet snow sluff on the E Face of Tamarack Peak involving the storm snow.

Avalanche Discussion

* Variable amounts of new snow exist on top of old melt-freeze crusts across the region. Spring sun and warmth are melting this storm snow quickly. The Mt. Rose area has the most storm snow (10 to 12 inches initially - less each day due to settlement and melting) and will take the longest to transition. Most areas along the Sierra Crest only had a few inches of storm snow and will melt/transition faster. 

* Variable firm surfaces exist in the mornings. Many areas become soft and wet in the afternoons. Some areas also hold breakable crusts over colder snow. NE wind scoured surfaces exist near many ridgelines.

* Some drifts of wind-blown snow formed during the storm, but the drifts remained shallow and do not extend very far from the ridges. No signs of wind slab instability have been reported. 

Regions covered