Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Lingering areas of unstable deposits of wind drifted snow and warming of recent new snow are the avalanche concerns for today. Move cautiously around slopes below cornice areas and on slopes where roller balls or pinwheels are occurring. Avalanche concerns for today are greatest in the northern half of the forecast area where the highest amounts of new snow accumulation occurred during the past 36 hours.

Avalanche problems

  • Wind Slabs

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

    Deposits of wind drifted snow were observed yesterday at up to 6 inches deep in the southern portion of the forecast area and up to 2 feet deep in the northern portion of the forecast area. Lingering wind slab instability remains a concern today and could be exacerbated by warming. Above treeline and near treeline terrain on NW-N-NE-E-SE aspects is the most likely location to encounter an unstable wind slab today. 

    Cornices above a slope, blowing snow, smooth drifted snow,  and wind-created snow surface textures can all help identify slopes where unstable wind slabs may exist. Recent slab avalanches and/or cracking in the wind-loaded snow are signs that wind slabs are unstable. Move cautiously around ridgetop areas, especially on slopes below or adjacent to cornice features or below pillows of wind drifted snow.

    (4/1/2023)

    An example of a shallow but problematic wind slab avalanche that carried a skier down this slope on Red Lake Peak in March of this year. 

    Photo: Public

  • Loose Wet

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

    It's late April. The midday sun angle is high and the amount of incoming solar radiation is intense. After a cold start to this morning, the warming of yesterday's new snow is expected today on all aspects. The most dramatic warming is expected below about 8,000', but will also affect higher elevation areas. Intense solar radiation will warm exposed rocks and trees triggering natural rollerballs even at higher elevations. Areas with large amounts of exposed rock such as along cliff bands and the walls of chutes and gullies will likely experience substantial warming today. This includes higher elevation areas where the actual air temperatures remain below freezing.

    Pay attention to snow surface warming if traveling in avalanche terrain today. Rollerballs and pinwheels are indications that the snow surface is becoming wet and unstable leading to the possibility of a wet loose avalanche. Long open slopes, especially in the northern half of the forecast area could experience sizable wet loose avalanches today. Consider exiting avalanche terrain once signs of unstable wet snow develop.

    (4/15/2023)

    Initially small wet loose avalanches can produce deep debris where they can run far on long open slopes.

    Photo: Public

Avalanche Discussion

  • Firm melt-freeze crusts exist below the recent new snow on all aspects.
  • Glide cracks have started to form on some steep slopes in rocky areas. The exact timing of glide crack avalanches is notoriously difficult to predict. Due to the uncertainty, consider avoiding travel on or below slopes with glide cracks.
  • Cornice fall remains an ongoing concern as air temperatures warm above freezing.
  • Large cracks have opened up behind many cornices, and falling into one of them could cause problems.

Regions covered