Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 5 years ago.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

Highlights

The possibility remains for wet loose snow avalanches on steep slopes in wind protected areas today, mainly below treeline. Some of these avalanches could entrain enough wet snow to cause problems for backcountry travelers especially on long steep slopes or in areas with terrain trapsMODERATE avalanche danger will exist today below treeline with LOW avalanche danger in wind exposed areas near treeline and above treeline.

Avalanche problems

  • Loose Wet

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

    Air temperatures were above freezing last night for most locations below about 8,500' to 9,000'.  Another decent but superficial snow surface refreeze is expected to have occurred last night on open slopes despite above freezing air temperatures due to radiational cooling of the snowpack under clear skies. The snow surface will likely not have refrozen well under areas of thick forest canopy. Substantial wind today is expected to provide convective cooling of the snow surface and slow melt rates in wind exposed areas. The majority of these slow to melt areas will exist near treeline and above treeline. Wind protected and sun exposed slopes will experience snow surface melt today. Most of these quicker to melt slopes will be found below treeline.

    Once more than a couple of inches of surface wet snow forms, wet loose avalanches that start small and then gain size with vertical run will be possible on all aspectsAvalanche size is expected at D1 to D2 depending on size of the slope. Terrain traps such as creek beds or cliffs could easily allow for burial or injury from what would otherwise be a size D1 avalanche.

    Slope angle is the easy way to manage this avalanche problem as most wet loose avalanches will occur on slopes 35 degrees and steeper. Once surface wet snow develops, roller balls and pinwheels are indications that unstable conditions are present. Move to slopes less than 30 to 35 degrees in slope angle without steeper slopes above to minimize exposure to this avalanche problem.

Avalanche Discussion

* Recent storm snow underwent melt for the first time on Saturday in many areas. The top 6 to 12 inches of the upper snowpack in locations above about 8,000' to 8,500' on E-SE-S-SW-W aspects and at most elevations on NW-N-NE aspects remains transitional (surface crust over recent storm snow) and is not well established in typical spring melt-freeze conditions. E-SE-S-SW-W aspects below about 7,500' to 8,000' have undergone more melt cycles and are getting closer to established melt-freeze conditions.

* Little to no snow is available for drifting at this time. This is expected to keep any problematic wind slabs from forming despite the windy conditions.

Regions covered