Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Loose wet avalanches will become possible today due to daytime warming. MODERATE avalanche danger will form on slopes steeper than 35 degrees on E-SE-S-SW-W aspects at all elevations and may form on some  below treeline NW-N-NE aspects. Clues like sinking into wet snow above your boot tops or small point releases, roller balls, or pinwheels can help determine when to move to more frozen aspects, onto lower angle slopes, or to switch to a different afternoon activity.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Since the recent snowfall, today will be the first day of clear skies, all day strong spring sunshine, and daytime highs in the 40's above 7000 ft. These warming factors will all combine to cause rapid warming in the recent snow. This warming will turn the recent snow into unconsolidated wet snow. Below this wet snow, old frozen crusts that make good bed surfaces exist on all aspects. Loose wet snow sitting on top of an efficient bed surface means that loose wet avalanches will be possible today. Some of the loose wet avalanches that occur today could entrain enough snow to cause problems for backcountry travelers especially in areas where the loose wet avalanches involve terrain traps. Slopes steeper than 35 degrees on sun-exposed E-SE-S-SW-W aspects at all elevations will hold the best potential for loose wet avalanches since they should experience the most warming, but some of the below treeline NW-N-NE aspects could also see enough sun for some wet snow instabilities to form.

    Sinking into wet snow above your boot tops and small surface instabilities like roller balls, pinwheels, or point releases can provide clues that enough wet snow has formed for larger loose wet avalanches to become an issue. Moving to more frozen slopes or onto lower angle slopes off and away from slopes 35 degrees or steeper before deep wet snow exists on a slope represents a wise choice for today. Terrain traps like gullies, creeks, and cliffs can greatly increase the risk of any size loose wet avalanches.

Avalanche Discussion

Observations on Relay Peak in the Mt. Rose backcountry showed wind scoured surfaces and exposed frozen crusts on the above treeline exposed NE-N-E aspects. Some minor wind slabs had formed on the W-SW-S aspects but they remained small, did not extend more than 10 ft. down slope, and tests on them did not produce any signs of instabilities. The snow on Relay Peak remained cold and had not experienced any melt-freeze cycles. 

Across the Lake on Donner Peak near Donner Summit, March sunshine had allowed wet surface snow to form on E-SE-S-SW aspects up to at least 8000 ft. and on some N-NE-ENE aspects below about 7800 ft. Many natural loose wet point releases occurred on the east face of Donner Peak near exposed rocks on 3/29 and 3/30. Most of these were relatively small and but some did entrain enough snow to interfere with backcountry travel. Ski cuts on NE-ENE-E-SE facing test slopes also produced loose wet point releases, pinwheels up to 2 ft. in diameter, and ski width wide wet snow sluffs yesterday. 

Regions covered