Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Open full map
Out of date — this forecast expired 10 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Moderate avalanche danger continues due to ongoing wind slab problems on NW-N-NE-E-SE aspects near and above treeline on slopes steeper than 35 degrees.  As daytime warming occurs, avalanche danger will also increase to moderate on E-SE-S-SW-W aspects at all elevations due to the possibility of loose wet avalanches.  Human triggered avalanches continue to be possible today.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    Wind slabs from the Sunday/Monday storm continue to gain strength with snowpack tests showing good bonding in many areas.  In isolated areas throughout the forecast area, recent human triggered avalanche activity and snowpack tests show that these wind slabs still remain a problem.  Areas of greatest concern are steep unsupported terrain and complex terrain with many trigger points on NW-N-NE-E-SE aspects near and above treeline.  Large loads may be required to trigger some of these wind slabs like multiple people on a slope at a time or large cornice fall.

    Identify and avoid steep wind loaded terrain. Use clues such as recent test slope failures, cornice formations, wind pillows, snow surface scouring and snowpack tests to determine where suspect wind slabs exist.  Practice safe backcountry travel protocols:  only expose 1 person on a slope at a time, use clear communication within your group, and regroup in safe areas away from avalanche runout zones

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Warming temperatures, light winds, and full sun today will make loose wet avalanches possible on E-SE-S-SW-W aspects at all elevations and on NW-N-NE aspects below treeline.  Most of these instabilities should be in the form of roller balls and pinwheels and could be both natural and human triggered.  Larger loose wet avalanches could become possible today that could entrain enough snow to bury or injure a backcountry user. 

    Timing is critical as daytime warming occurs today.  Shallow snow areas with rocks or vegetation may become unstable first.  Roller balls or pinwheels are a sign that the snow surface is loosing strength and that larger loose wet avalanches may become possible.  Avoid slopes steeper that 35 degrees or being under steep slopes as daytime warming occurs.

Avalanche Discussion

2 snowmobilers were caught in an avalanche in Polaris Bowl near the Blue Lakes Road in the Carson Pass area on Tuesday.  The avalanche was 100' wide, 300' long, with a crown up to 3' deep and involved a cornice collapse.  1 sled was partially buried with no riders being buried.  The slide was just over 9000' in elevation, East aspect, 40 degree slope, and occurred around 3pm. 

A snowmobiler triggered avalanche from Monday was investigated yesterday that occurred on Relay Peak (Mt. Rose area).  Avalanche was 150' wide, ran downslope 300', with a crown up to 2' deep.  The avalanche was just below ridgeline in heavily wind loaded terrain with many trigger points (rocks and small trees) visible in the start zone.  Avalanche was at 10,125' in elevation, E-SE aspect, 38 degree slope.  No rider was caught in this avalanche.  Snowpack tests showed 1 ECTP result at the crown with several ECT's throughout the immediate area showing no propagation results.

Snowpack tests from the North side of Carson Pass showed ECTP results on wind slabs.  Many large overhanging cornices were also noted throughout the area.

Many reports have come in of other avalanche activity that occurred during or just after the Sunday/Monday storm cycle-see the observation page for more details.

 

Regions covered