THIS AVALANCHE ADVISORY EXPIRED ON January 13, 2016 @ 6:52 am
Avalanche Advisory published on January 12, 2016 @ 6:52 am
Issued by Steve Reynaud - Tahoe National Forest

Pockets of Moderate avalanche danger exists on N-NE-E-SE aspects near treeline and below treeline due to the Jan 5 buried surface hoar layer.  Persistant slabs are possible today in terrain where this weak layer occurs.  In areas where this weak layer is absent, Low avalanche danger exists.  Evaluate snow and terrain carefully, identify features of concern.



 

1. Low

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

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: Persistent Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

The Jan 5 buried surface hoar layer is down 1-1.5' deep in the snowpack and has been reactive since last Tuesday.  Snowpack tests continue to show that this layer has not stabilized and that propagation is possible.  The areas of concern are N-NE-E and possibly SE aspects near treeline and below treeline in open but protected terrain.

The Jan 5 buried surface hoar layer does not exist everywhere and is not a common problem for our area.  This problem will be limited to near and below treeline terrain, not the upper elevation avalanche starts zones that we normally deal with.  Use careful terrain selection to avoid steep, open slopes near and below treeline.  Use proper travel techniques to help limit the risk for you and your group.

recent observations

Observations from Deep Creek (Cabin Creek area) showed the presence of the 1/5 buried surface hoar layer.  In some places this layer was not reactive and in others it showed consistent results with snowpack tests that propagation is still possible.  Other observations from Carpenter Ridge (Independence Lake area) and Mt. Judah (Donner Summit area) did not find the 1/5 buried surface hoar layer present.  Where this layer is not found, the snowpack is well bonded and consolidated with no signs of instability.

The Jan 5 buried surface hoar layer is known to exist in various areas on Donner Summit, Deep Creek, and some areas on Carson Pass.  It has not been observed at Barker Pass (Blackwood Canyon area), Echo Peak (Echo Summit area), Jakes Peak (West Shore area), and Mt. Tallac (Desolation Wilderness area).

The last avalanche activity associated with this weak layer was last Thursday on Andesite Peak (Donner Summit area) and Thursday and Friday on Red Lake Peak (Carson Pass area).  These avalanches were human triggered, 1-1.5' deep, and occurred on NE-E aspects near treeline and below treeline.



 

Weather and CURRENT CONDITIONS
weather summary

High pressure will remain in place today with dry conditions.  The next low pressure system is approaching our area tonight and should bring increasing winds and high cirrus clouds into the area later this afternoon and into the evening.  A winter weather advisory is in effect from 4am to 10pm Wednesday with modest snow amounts and higher density snow than we've seen in the past week. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 24 to 26 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 10 to 15 mph
Maximum wind gust in the last 24 hours: 31 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 48 to 58 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Tuesday Tuesday Night Wednesday
Weather: Partly cloudy then becoming mostly cloudy. Cloudy. Slight chance of rain and snow after midnight. Cloudy. Snow.
Temperatures: 35 to 42 deg. F. 21 to 28 deg. F. 26 to 33 deg. F.
Wind Direction: SW SW SW
Wind Speed: 15 to 20mph with gusts to 30mph. 30 to 40mph with gusts to 50mph then increasing to 60mph after midnight. 30 to 40mph with gusts to 60mph.
Expected snowfall: 0 in. 0 in. 3 to 7 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Partly cloudy then becoming mostly cloudy. Cloudy. Slight chance of snow after midnight. Cloudy. Snow.
Temperatures: 33 to 40 deg. F. 20 to 27 deg. F. 24 to 31 deg. F.
Wind Direction: SW SW SW
Wind Speed: 20 to 30mph with gusts to 35mph increasing to 45mph in the afternoon. 45 to 50mph with gusts to 75mph increasing 60 to 65mph with gusts to 95mph. 50 to 60mph with gusts to 90mph.
Expected snowfall: 0 in. 0 in. 3 to 7 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.