THIS AVALANCHE ADVISORY EXPIRED ON April 9, 2017 @ 6:59 am
Avalanche Advisory published on April 8, 2017 @ 6:59 am
Issued by Andy Anderson - Tahoe National Forest

CONSIDERABLE avalanche danger exists at all elevations today. Human triggered wind slab avalanches are likely on wind-loaded slopes and storm slab avalanches are possible in more sheltered locations. Dangerous avalanche conditions exist. Plan travel routes to avoid steep slopes where avalanche problems may exist. Evaluate snow and terrain carefully. If areas receive more snow and higher snowfall rates than forecasted, more avalanche danger could exist. 

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Large, deep, and fragile wind slabs will exist on wind-loaded slopes, and avalanches involving these wind slabs could have serious consequences. Continued wind and snow in the last 24 hours have formed additional wind slabs on top of the previous wind slabs. As more snow and wind impact the forecast area today, these wind slabs will continue to grow. Human triggered wind slab avalanches will be likely today and natural wind slab avalanche will be possible. The largest and most fragile wind slabs will exist on the wind loaded N-NE-E aspects and on cross-loaded NW and SE aspects in near and above treeline terrain, but wind slabs could also exist in some below treeline areas due to the strength of the winds. 

Identify where wind slabs might exist by using clues like blowing snow, wind drifts, cornices above slopes, wind-created ripples, and other wind created features. Use this information to avoid the wind slabs and to find sheltered non-wind-affected snow for better and safer recreation.

Avalanche Problem 2: Storm Slab
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Changing conditions during the storm have created softer weaker layers and stronger more slab-like layers within the storm snow. Some human triggered storm slab avalanches may be possible today in areas where the stronger slab-like layers exist above the softer weaker layers of storm snow. Storm slabs could exist on steep slopes in non-wind-affected terrain and could involve enough snow to bury or injure a person. The areas that receive the most new snow and highest snowfall rates will represent the best places to find storm slabs.

Recent avalanche activity, shooting cracks, snowpits, and probing can all help identify where storm slabs may exist. Use this information to avoid steep slopes where storm slabs may exist. 

recent observations

Yesterday observations on Powderhouse Peak, Incline Lake Peak, and Andesite Peak all found new snow sitting on top of refreezing rain crusts. New snow amounts varied from 10 to 18 inches. Strong winds and dense snow had formed stubborn wind slabs that would crack under repeated ski kicks on wind-loaded test slopes. Snowpit tests on Incline Lake Peak indicated that storm slab instability existed in some areas as well. 

Weather and CURRENT CONDITIONS
weather summary

Another 10 to 18 inches of new snow has fallen above 7000 ft. in the last 24 hours. Most of this accumulation occurred last night as another wave of heavy precipitation pushed into the region. Widespread heavy snow should start to taper off this morning. By this afternoon convective snow showers should become the primary accumulation producers. These convective showers will impact some areas and not others so snow totals could vary greatly from area to area. The forecast calls for most places to receive 6 to 12 inches of snow today, but some isolated places where the most intense snow showers occur may get more. Snow showers should come to an end overnight as the storm departs the region. The winds are predicted to follow the same pattern with strong southwest winds continuing through today then decreasing and shifting to the west and south as the storm departs. Cold air will remain over the region tonight, but some warming may start to occur tomorrow under partly cloudy skies. 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 20 to 28 deg. F.
Max. temperature in the last 24 hours: 29 to 34 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 55 to 65 mph
Maximum wind gust in the last 24 hours: 120 mph
New snowfall in the last 24 hours: 10 to 18 inches
Total snow depth: 131 to 197 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Cloudy with snow showers Cloudy with a chance of snow showers in the evening becoming partly cloudy overnight Partly cloudy
Temperatures: 25 to 30 deg. F. 13 to 21 deg. F. 33 to 39 deg. F.
Wind Direction: Southwest West Variable
Wind Speed: 20 to 35 mph with gusts to 65 mph 15 to 25 mph with gusts to 45 mph in the evening becoming light overnight Light
Expected snowfall: 6 to 12 in. up to 1 in. 0 in.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Cloudy with snow showers Cloudy with a chance of snow showers in the evening becoming partly cloudy overnight Partly cloudy
Temperatures: 21 to 27 deg. F. 12 to 18 deg. F. 29 to 35 deg. F.
Wind Direction: Southwest West South
Wind Speed: 30 to 50 mph with gusts to 85 mph decreasing to gusts to 65 mph in the afternoon 20 to 30 mph with gusts to 50 mph decreasing to 10 to 15 mph with gusts to 35 mph after midnight 10 to 15 mph with gusts to 35 mph
Expected snowfall: 6 to 12 in. up to 1 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