THIS AVALANCHE ADVISORY EXPIRED ON March 13, 2016 @ 8:00 am
Avalanche Advisory published on March 12, 2016 @ 7:00 am
Issued by Andy Anderson - Tahoe National Forest

MODERATE avalanche danger exists on slopes steeper than 35 degrees on near and above treeline NW-N-NE-E-SE aspects due newly formed wind slabs. Most wind slabs will exist along the Sierra Crest above 7500 ft. where more snow accumulated. Evaluate snow and terrain carefully, and identify areas where avalanche problems exist. The avalanche danger will increase quickly as more snow and wind impact the region starting this evening with wind slabs and storm slabs becoming more problematic during the storm. 

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.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    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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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Yesterday's new snow and wind created wind slabs on the wind loaded N-NE-E and cross loaded NW and SE aspects. Human triggered wind slab avalanches involving these wind slabs will remain possible today. Additional snow and wind today will mean that these wind slabs will continue to grow. The largest and most problematic wind slabs should remained confined to the Sierra Crest on wind loaded aspects above 7500 ft. where more snow instead of rain accumulated over the last 24 hours. Some smaller more isolated wind slabs may form in other areas as snowfall becomes more widespread today. Wind slabs as well as storm slabs will become much more widespread and problematic as more snow and wind impact the forecast area starting this evening. 

Identify and avoid steep wind loaded slopes.  Look for areas of blowing snow, cornice formation, wind scouring, and wind pillows to help determine where wind slabs exist.

recent observations

Yesterday observations on Incline Lake Peak in the Mt. Rose area showed a thin layer of graupel resting on top of a breakable crust on all aspects. Observations did not reveal any signs of instability in the existing snowpack in this area. Across the Lake on Scout Peak near Echo Summit new heavy wet snow accumulated above a breakable crust with wet snow below it in areas above 7800 ft. Below that elevation the snow surface remained wet and the precipitation fell as a mix of rain and snow. Some human triggered pinwheels did occur in this area. A report came in from the Blue Lakes area south of Carson Pass that snowmobilers saw several avalanches but could not gather more details due to a lack of visibility and deteriorating conditions.

Weather and CURRENT CONDITIONS
weather summary

Yesterday and into last night the Sierra Crest received 3 to 7 inches of new snow above 7800 ft. Areas below 7800 ft. received 1 to 4 inches and a mix of rain and snow with most of the precipitation falling as rain below 7000 ft. The southwest winds remained strong during the night, and they should continue today. The precipitation tapered off, and skies did clear some overnight. This short break in the weather should continue until this afternoon when cloud cover increases and a chance for more snow returns with the leading edge of a large winter storm. Up to 3 more inches could accumulate by the end of today. Snow levels should remain around 6000 ft. through tonight. Snowfall should begin in earnest this evening, and the forecast calls for 4 to 8 inches overnight. The gale force southwest winds should continue through tomorrow as well. Another stronger wave of the storm impacts the region Sunday and continues through Sunday night into Monday morning. The initial thrust of this part of the storm should bring 6 to 12 inches of new snow accompanied by gale force winds during the day tomorrow. Snow levels may rise some during the day on Sunday to around 6500 ft. before falling back down below 5000 ft. by Monday morning. For more details and snow total predictions check in with the Reno NWS.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 23 to 27 deg. F.
Max. temperature in the last 24 hours: 33 to 37 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 40 to 50 mph
Maximum wind gust in the last 24 hours: 80 mph
New snowfall in the last 24 hours: 3 to 7 inches
Total snow depth: 74 to 104 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy with cloud cover increasing throughout the day. Slight chance of snow in the morning and a chance of snow in the afternoon Snow Snow
Temperatures: 35 to 41 deg. F. 24 to 31 deg. F. 34 to 40 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 20 to 30 mph with gusts to 50 mph 30 to 40 mph with gusts to 50 mph increasing to 60 mph after midnight 30 to 35 mph with gusts to 50 mph increasing to 40 to 45 mph with gusts to 65 mph in the afternoon
Expected snowfall: up to 2 in. 4 to 8 in. 6 to 12 in.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy with cloud cover increasing throughout the day. Slight chance of snow in the morning and a chance of snow in the afternoon Snow Snow
Temperatures: 27 to 34 deg. F. 21 to 28 deg. F. 26 to 33 deg. F.
Wind Direction: Southwest Southwest Southwest
Wind Speed: 50 to 60 mph with gusts to 90 mph 50 to 60 mph with gusts to 95 mph 50 to 60 mph with gusts to 90 mph
Expected snowfall: up to 3 in. 4 to 8 in. 6 to 12 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