THIS AVALANCHE FORECAST EXPIRED ON January 28, 2016 @ 6:40 am
Avalanche Forecast published on January 27, 2016 @ 6:40 am
Issued by Steve Reynaud - Tahoe National Forest

Avalanche danger remains low on all aspects and elevations.  Isolated areas of instability may exist.  Normal caution is advised.

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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  • Aspect/Elevation ?

Winds shifted back to the SW yesterday afternoon and will be in the moderate to high range above 8000' today.  This may cause some blowing snow and small wind slab development near and above treeline on exposed ridges and peaks.  These should remain small and isolated and not pose a risk for backcountry users today.  Look for visible blowing snow, cornice formation, wind pillows, and snow surface scouring as clues to identify suspect slopes.

Normal caution means exercising basic travel techniques.  Travel one at a time in avalanche terrain, regroup in safe spots out of the avalanche path, avoid travel near terrain traps, and practice good communication within your group.

Forecast discussion

What happened to the deep persistent weak layer?

In early to mid January, up to 3 separate surface hoar layers formed and were buried by subsequent storms on N-NE-E aspects near treeline and below treeline.  These buried surface hoar layers are currently buried 1.5 to 4.5 feet deep in the snowpack.  A widespread persistent slab avalanche cycle occurred Jan 5 through Jan 19 on these weak layers.  Many slopes have been "cleaned out" by already avalanching, or the surface hoar has been collapsed or compressed and has gained strength.  Targeted observations and snowpack tests have shown that these layers, in the majority of locations, are no longer reactive and have assimilated into the snowpack.  No avalanche activity has been associated with these buried surface hoar layers since Jan. 19.

This deep persistent avalanche problem has become unlikely and has been removed as an avalanche problem.

recent observations

A small wind slab avalanche was skier triggered off of the top of Deep Creek Peak yesterday.  This occurred on a NE aspect, at 8400', directly off ridge top, with a crown height of 2 to 6'' deep. 

Other observations from Deep Creek showed a uniform and consolidated snowpack.  2 buried surface hoar layers were observed (1/9 and 1/13 layers) and both were found to be rounding and not reactive to snowpack tests.  4 to 6'' of unconsolidated snow existed on northerly aspects.

Observations from Stanford Rocks (Ward Canyon area) showed similar conditions.  Snowpack tests targeting the 1/9 buried surface hoar layer showed this layer to be gaining strength and not reactive.  The recent 1/23 rain crust is present below 8000' and only covered by 3-4'' of snow at lower elevations.  This crust is mostly supportive but on southerly aspects it is more variable and breakable in locations.  No signs of instabilities existed in this area.

Weather and CURRENT CONDITIONS
weather summary

High pressure will continue through today with warm and dry conditions.  Highs will be in the mid 40's for areas around 7000'.  SW winds will be in the moderate to strong range above 8000'.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 28 to 35 deg. F.
Max. temperature in the last 24 hours: 34 to 45 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 15 to 20 mph
Maximum wind gust in the last 24 hours: 31 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 74 to 82 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy. Partly cloudy. Partly cloudy then becoming mostly cloudy. Slight chance of rain in the afternoon.
Temperatures: 37 to 47 deg. F. 26 to 32 deg. F. 40 to 47 deg. F.
Winds: SW SW SW
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy. Partly cloudy. Partly cloudy then becoming mostly cloudy. Slight chance of rain and snow in the afternoon.
Temperatures: 35 to 45 deg. F. 25 to 35 deg. F. 34 to 44 deg. F.
Winds: SW W SW
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.