THIS AVALANCHE ADVISORY EXPIRED ON December 6, 2016 @ 6:45 am
Avalanche Advisory published on December 5, 2016 @ 6:45 am
Issued by Andy Anderson - Tahoe National Forest

LOW avalanche danger exists on all aspects and elevations. LOW danger does not mean "no danger" and small unlikely but not impossible avalanches could still occur in isolated areas or extreme terrain. Practice safe backcountry travel habits like moving one at a time from safe zone to safe zone while traveling through avalanche terrain. Early season conditions exist with numerous exposed and shallowly buried obstacles in most areas.

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
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Triggering an avalanche remains unlikely today; however, some unstable snow could still exist on isolated terrain features especially in complex or extreme terrain. Even though the avalanche danger remains LOW continue to practice safe back-country travel habits. Make a travel plan, discuss it with your group, and share it with someone who will not be on your trip. Continue to evaluate the snowpack and terrain and watch out for those isolated terrain features where unstable snow may remain. When moving into or through potential avalanche terrain, only expose one member of your group at a time. Identify safe zones out of avalanche terrain and re-group in those areas. Practicing these techniques now will make them habits that will serve you well when increased avalanche danger exists.

While LOW avalanche danger means less avalanche hazard, the shallow snowpack means more exposed or barely covered rocks, logs, stumps, trees, and other hard immovable objects to hit. Collisions with these obstacles can break equipment and people. Enjoy the snow, but be careful so that the enjoyment will last all season long.

advisory discussion

The Sierra Crest north of Tahoe City and the Mt. Rose backcountry harbor the deepest and most usable snowpack within the forecast area. Even in these more snow covered areas early season conditions still persist and many obstacles remain. Along the Sierra Crest south of Tahoe City, the snowpack becomes more shallow with many more exposed and barely covered obstacles even at the upper elevations.

recent observations

Yesterday observations from Becker Ridge, Castle Peak, and Relay Peak showed a mix of snow surface conditions ranging from wind crusts to sun crusts to wind scoured slopes to warm sticky snow to soft cold snow. The near and above treeline N-NE-E aspects held wind scoured slopes with firm icy surfaces while the sheltered N facing slopes in near and below treeline terrain still held areas soft unconsolidated snow. At the upper elevations on Castle Peak and Relay Peak this soft snow remained cold, but at the lower elevations on Becker Ridge, it became wet and sticky as the day warmed up.

Snowpit data from all three of these areas found layers of weak sugary snow in the bottom third of the snowpack. On Becker Peak below 8000 ft. this weak layer exhibited signs of slowly consolidating; however, at the higher elevations where the snowpack remained colder on Castle Peak and Relay Peak it showed signs weakening. Tests on these persistent weak layers indicated that triggering them remains unlikely at this time, but that they have the potential to re-activate under future loading on the colder upper elevation N facing slopes. These layers could become the foundation for the next persistent slab problem when more snow arrives in the region. So far these persistent weak layers exist and remain weak on N aspects along the Sierra Crest above 8300' and in the Mt. Rose area above 9300'. There have been no avalanches associated with these layers.

Weather and CURRENT CONDITIONS
weather summary

The forecast calls for cooler temperatures, increased SW winds, and partly cloudy skies today as a weak cold front approaches the region. Temperatures should continue to fall and winds should continue to increase as this front arrives over the area tonight. Overnight lows could fall into the teens above 7000 ft. Cold air will remain over the region tomorrow with daytime highs in the 20's above 7000 ft. This small system also brings a slight chance of snow showers to the area tomorrow; however, the forecast calls for accumulation to remain limited to less than an inch if the snow showers do materialize. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 25 to 31 deg. F.
Max. temperature in the last 24 hours: 35 to 45 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 20 to 30 mph
Maximum wind gust in the last 24 hours: 58 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 8 to 21 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy Partly cloudy Partly cloudy with a slight chance of snow showers
Temperatures: 36 to 42 deg. F. 17 to 22 deg. F. 25 to 31 deg. F.
Wind Direction: Southwest Southwest West
Wind Speed: 10 to 15 mph with gusts to 45 mph 10 to 15 mph with gusts to 50 mph 15 to 25 mph with gusts to 60 mph
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy Partly cloudy Partly cloudy with a slight chance of snow showers
Temperatures: 32 to 40 deg. F. 16 to 21 deg. F. 20 to 28 deg. F.
Wind Direction: West West West
Wind Speed: 20 to 35 mph with gusts to 75 mph 20 to 30 mph with gusts to 75 mph increasing to 30 to 45 mph with gusts to 95 mph after midnight 30 to 50 mph with gusts to 100 mph decreasing to 85 mph in the afternoon
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258