Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 6 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avalanche danger is rising. Backcountry travelers could easily trigger large avalanches today, especially once 6+ inches of new snowfall is surpassed. Consider avoiding avalanche terrain in areas where clues to unstable snow are present, such as slopes filling in with drifting snow, snow surface cracking, or snowpack collapses.

HIGH avalanche danger is expected tonight and tomorrow.

Avalanche problems

  • Storm Slabs

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

    Areas of unstable snow are expected to form first on slopes that are filling in with wind loaded snow, spreading to include wind protected areas below treeline as the day progresses. Identify areas where visible drifting snow is depositing and filling in on slopes of concern. Signs of unstable snow include cracking, collapsing, or recent avalanches. These clues to unstable snow are expected to spread to wind protected slopes below treeline as the day progresses. Identify slopes that hold potentially unstable snow and consider avoiding them.  Tighten up your travel practices today. Focus on very clear communication within your group and do not rely on marginal islands of safety in or below avalanche terrain.

    High intensity snowfall will rapidly create new storm slabs today. Once new snow amounts surpass 6+ inches, all avalanche terrain will become suspect. Where the additional new snow load is added above the weak, faceted (sugary) Feb 10 layer across NW-N-NE aspects, avalanches could break wider than expected or trigger from lower on the slope than expected. Any collapses or whumpfing noises indicate that you have found a slab on top of the Feb 10 layer. The same advice applies here: Identify slopes that qualify as avalanche terrain and consider avoiding them.

    Snow surface cracking like this indicates that you have found unstable snow. Where this is the case, consider opting for slopes with a slope angle under 30 degrees until you have navigated away from avalanche terrain.

    This photo was taken earlier this year near Blue Lakes, CA.

    Photo: Jason Bilek

Avalanche Discussion

Weak snow (near-surface facets) formed on many NW-N-NE aspects during the recent, extended dry spell. This weak layer was buried by new snow on Feb 10. Most areas have a thin rain crust along the top of the facet layer up to 8,600 to 8,800 ft. This weak layer is expected to begin to fail either today or tomorrow. Weak layers, similar to the Feb 10 facet layer, have contributed to large avalanches and avalanche fatalities within our forecast area in the past.

Lower elevation areas and sun-exposed slopes experienced significant snowmelt over the past 3 weeks, exposing areas of dirt, rock, and downed trees.  These hazards and obstacles now lie hidden, barely covered by new snow. This creates a hazard situation similar to early season coverage in some areas.  Additionally, deep open holes, open creeks, and ponded water are widespread in low-lying areas, especially below 8,000'. 

Regions covered