THIS AVALANCHE ADVISORY EXPIRED ON January 8, 2016 @ 7:02 am
Avalanche Advisory published on January 7, 2016 @ 7:02 am
Issued by Andy Anderson - Tahoe National Forest

Human triggered avalanches remain possible today due to lingering wind slabs and storm slabs. MODERATE avalanche danger exists on all elevations and aspects on slopes 35 degrees and steeper. Evaluate snow and terrain carefully before committing to any slopes. 

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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New snow and shifting winds since Jan. 5th have created wind slabs on leeward aspects. Additional wind and snow last night caused these wind slabs to continue to grow in size and extent. These wind slabs have started to bond to themselves and the snow below them, but human triggered wind slab avalanches will remain possible today. The most sensitive wind slabs will exist on wind loaded slopes in near and above treeline terrain. Due to the winds shifting between south and southwest these wind slabs could exist on wind loaded NW-N-NE-E aspects as well as cross loaded W and SE aspects. Avalanches resulting from the failure of these wind slabs would easily involve enough snow to bury a person and could be even larger in the most heavily wind loaded areas.  

Avalanche Problem 2: Storm Slab
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Like the wind slabs mentioned above storm slabs have also become more difficult to trigger since they have started bonding to the snow below them. Still the possiblity remains for a human triggered storm slab avalanche that fails on a lingering weakness in the storm snow or on the interface between the storm snow and the old snow below it. Steep northerly facing slopes in near and below treeline terrain represent the most likely places to find lingering storm slabs, but they could still exist on any aspect in near and below treeline terrain. Storm slabs that have the ability to propagate far distances or be remotely triggered have become more unlikely, but that potential may still exist in a few isolated areas. 

recent observations

Yesterday, observations on Andesite Peak showed that the storm slabs from Jan. 5th had started to bond to the snowpack below them. Snowpit tests and ski cuts on test slopes in near and below treeline terrain did not produce signs of instabilities on the interface between the recent snow and the old snow. On Rubicon Peak some snowpit and hand pit tests showed signs of instability concerning the storm slabs in near and below treeline terrain and other tests did not. Yesterday morning in more exposed near and above treeline terrain on Andesite Peak and Rubicon Peak, some shooting cracks did occur on wind loaded test slopes. On Andesite cornice pieces dropped onto these wind slabs triggered the cracking. On Rubicon ski kicks/cuts triggered it. The wind slabs measured 2-3 ft. in depth. A few hours later during the afternoon on Rubicon, ski cuts on similar wind loaded test slopes failed to trigger additional shooting cracks.

Weather and CURRENT CONDITIONS
weather summary

4 to 8 inches of new snow has fallen in the last 24 hours. Snow showers may continue this morning, but they should become scattered and provide little additional accumulation. The low pressure responsible for this storm will continue to progress eastward today leaving unsettled but calmer weather over the region this afternoon and tomorrow. The forecast calls for light winds, continued cloud cover, and some isolated snow showers for the next 36 hours.  

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 19 to 23 deg. F.
Max. temperature in the last 24 hours: 24 to 28 deg. F.
Average wind direction during the last 24 hours: South to southwest
Average wind speed during the last 24 hours: 20 to 30 mph
Maximum wind gust in the last 24 hours: 71 mph
New snowfall in the last 24 hours: 4 to 8 inches
Total snow depth: 56 to 67 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Cloudy with scattered snow showers Cloudy with scattered snow showers Mostly cloudy with a slight chance of scattered snow showers
Temperatures: 21 to 28 deg. F. 12 to 18 deg. F. 22 to 29 deg. F.
Wind Direction: Variable West Variable
Wind Speed: Light 10 to 15 mph in the evening decreasing overnight Light
Expected snowfall: up to 1 in. trace to 0 in. 0 in.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Cloudy with scattered snow showers Cloudy with scattered snow showers Mostly cloudy with a slight chance of scattered snow showers
Temperatures: 17 to 24 deg. F. 7 to 14 deg. F. 19 to 26 deg. F.
Wind Direction: West West West
Wind Speed: 10 to 15 mph with gusts to 25 mph 10 to 20 mph with gusts to 30 mph 10 to 15 mph in the morning becoming light in the afternoon
Expected snowfall: up to 1 in. trace to 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.