THIS AVALANCHE ADVISORY EXPIRED ON March 16, 2016 @ 6:55 am
Avalanche Advisory published on March 15, 2016 @ 6:55 am
Issued by Steve Reynaud - Tahoe National Forest

Moderate avalanche danger exists on NW-N-NE-E-SE aspects near and above treeline on slopes steeper than 35 degrees due to ongoing wind slab problems.  As daytime warming occurs, moderate avalanche danger will also become possible on E-SE-S-SW-W aspects at all elevations due to loose wet avalanches.  Evaluate snow and terrain carefully, identify features of concern. 

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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Natural and human triggered wind slab avalanches have occurred over the last couple days throughout the forecast area.  Gale force SW winds have built up large wind slabs that are slowly gaining strength.  Most windward slopes are scoured down to firm crusts with little additional snow available for winds to transport.  No additional wind slab development is expected although current wind slabs could still be reactive and human triggering remains possible.

Identify and avoid steep wind loaded terrain. Use clues such as recent avalanche activity, test slope failures, blowing snow, cornice formations, wind pillows, snow surface scouring and shooting cracks to determine where wind slabs exist.

Avalanche Problem 2: Loose Wet
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As daytime warming occurs, loose wet avalanches will become possible on E-SE-S-SW-W aspects on slopes steeper than 35 degrees.  Most of these instabilities should be in the form of roller balls and pinwheels and could be both natural and human triggered.  Depending on how much solar radiation and warming we receive today, some larger loose wet avalanches could become possible that could entrain enough snow to bury or injure a backcountry user.  Wet snow instabilities could also form on NW-N-NE aspects that are in the sun or at lower elevations.

 

 

recent observations

A boarder triggered wind slab avalanche was reported in the East Gully on Waterhouse Peak yesterday.  The avalanche occurred at 9200' on an East aspect and was 50' wide, ran 200' downslope and was 1' deep.  A cornice collapse was also reported from the Donner Summit area and was skier triggered on a small wind feature.

Observations from Jakes Peak (West Shore area) and Powderhouse Peak (Luther Pass area) showed unstable snowpack test results but very little instability from test slopes and informal observations.  Gale force winds were moving large amounts of snow and scouring windward areas down to firm crusts.  Snow surface conditions were wind affected at all elevations with heavy and grabby snow reported.  Rain crusts were observed up to at least 7000'.

 

Weather and CURRENT CONDITIONS
weather summary

High pressure begins to build into our area today with dry weather and lighter winds into the weekend.  A warming trend will occur this week with temperatures today in the low to high 40's above 7000'.  Winds will be strong from the West and could gust up to 50mph above 8000'.  High thin clouds are expected today with periods of sun.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 17 to 27 deg. F.
Max. temperature in the last 24 hours: 32 to 38 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 30 to 40 mph
Maximum wind gust in the last 24 hours: 87 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 89 to 125 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Tuesday Tuesday Night Wednesday
Weather: Mostly cloudy then becoming partly cloudy. Partly cloudy then becoming clear. Sunny
Temperatures: 43 to 49 deg. F. 18 to 25 deg. F. 44 to 51 deg. F.
Wind Direction: W NW
Wind Speed: 15 to 25mph with gusts to 35mph. Northwest 15 to 20mph shifting to the East after midnight. Gusts to 30mph. Light winds.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Tuesday Tuesday Night Wednesday
Weather: Partly cloudy. Partly cloudy then becoming clear. Sunny
Temperatures: 40 to 46 deg. F. 18 to 25 deg. F. 40 to 47 deg. F.
Wind Direction: W NW becoming E SE
Wind Speed: 25 to 35mph with gusts to 50mph. Northwest 25 to 30mph with gusts to 45mph becoming East 15 to 20mph with gusts to 30mph after midnight. 10 to 15mph with gusts to 25mph.
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