Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Warm and sunny conditions today will create widespread areas of unstable wet snow. Natural avalanches are expected in steeper terrain. Once rollerballs and pinwheels are occurring, it is time to exit avalanche terrain.

Avalanche problems

  • Loose Wet

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

    We received more sunshine than forecast yesterday and it gave a preview of what is in store for today. The high sun angle of late April and strong incoming solar radiation will combine with warming air temperatures today to create unstable wet snow. Natural and human triggered wet loose avalanches are expected today on all aspects at all elevations as the 1.5 to 2.5 feet of recent storm snow undergoes warming and melt.

    Air temperatures are well below freezing at sunrise this morning so there will be a short window early this morning before widespread instability occurs. Once rollerballs and pinwheels are present, it is time to exit avalanche terrain. The sun angle is so high this time of year that changing aspects may not provide an escape from wet snow. Avalanches large enough to bury or injure a person are expected on longer slopes with sustained steepness of around 35 degrees or more.

    (4/22/2022)

    Natural loose wet avalanche on Flagpole Peak, Echo Summit, CA.

    Photo: David Reichel

  • Cornices

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

    Cornices that formed during this last storm cycle will weaken with daytime warming and may collapse. Identify and avoid areas of overhung cornice. Stay well back from the edge and don't linger on slopes below overhung cornices.

Avalanche Discussion

  • The non-persistent weak layer that contributed to wide propagating avalanches on April 21 appears to have bonded into the recent storm snow and become unreactive.
  • Some areas of sun crust and melt-freeze crust will have formed on the snow surface following yesterday's periods of sunshine and last night's refreeze.
  • Snow coverage has improved greatly since April 10th, especially along the Sierra Crest in the northern half of the forecast area. Many NW-N-NE-E aspects have good snow coverage. Snow cover on most SE-S-SW-W aspects is much thinner, mostly limited to the snow that accumulated since April 10.

Regions covered