THIS AVALANCHE ADVISORY EXPIRED ON March 27, 2017 @ 6:53 am
Avalanche Advisory published on March 26, 2017 @ 6:53 am
Issued by Steve Reynaud - Tahoe National Forest

Moderate avalanche danger exists due to wind slab and loose wet avalanche problems.  Wind slabs continue to exist on steep slopes in near treeline and above treeline terrain with new wind slab formation expected late this afternoon.  Loose wet avalanche activity will be possible at all elevations as rapid warming and/or rain occur today.  Human triggered avalanches remain possible. 

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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Wind slabs continue to remain possible on NW-N-NE-E-SE aspects in near treeline and above treeline terrain on slopes steeper than 35 degrees.  Rapid warming today due to solar radiation or rain could make these wind slabs more sensitive to human triggering.  As the next storm approaches this afternoon/evening, new wind slabs will form from new snow with strong to gale force SW winds.

Avoid steep wind loaded slopes and areas below cornices.  As new snow begins to accumulate this afternoon, look for blowing snow, cornice formation, and wind pillows.  Make a plan to avoid slopes that are being actively wind loaded

Avalanche Problem 2: Loose Wet
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Loose wet avalanches will be possible today due to rapid warming on E-SE-S-SW-W aspects at all elevations and on NW-N-NE aspects below treeline.  Some areas may experience rapid warming due to solar radiation, especially during the morning hours in areas away from the Sierra Crest.  Areas near the Sierra Crest up to 8000', have the possibility of light rain ahead of the next storm system.  Rain on top of the recent storm snow could cause widespread loose wet avalanche activity.

If the snow surface becomes wet, it is time to switch aspects to colder snow or leave the area.  Loose wet avalanches large enough to injure or bury a backcountry user are possible.  Terrain traps, such as gullies, can magnify the consequences of even a small loose wet avalanche.

recent observations

Observations were made and received from Mt. Tallac (Desolation Wilderness area), Negro Canyon (Donner Summit area), Talking Mountain (Echo Summit area), and Silver Peak (Pole Creek area).  A skier was caught in an avalanche on Mt. Tallac yesterday.  Information from the reporting party indicated that it was most likely a wind slab avalanche that received significant warming due to solar radiation.  The avalanche took the skier 800' downslope with minor injuries and broken gear reported.  Rapid warming and loose wet avalanches were reported from most of the forecast area although conditions ranged greatly depending on cloud cover. 

Weather and CURRENT CONDITIONS
weather summary

As the next storm approaches today, expect increasing clouds and SW winds with some light warm air advection precipitation possible.  Moderate to heavy snowfall is expected late afternoon into the early evening with 5 to 7'' of snow above 7000' forecasted.  Snow showers should decrease on Monday as a northerly flow develops behind the cold front as it exits our area.  Ridging builds into the area with drying and warming conditions until the next storm arrives late Wednesday/Thursday.

 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 22 to 29 deg. F.
Max. temperature in the last 24 hours: 39 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 30 to 50 mph
Maximum wind gust in the last 24 hours: 69 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 124 to 176 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Mostly cloudy. Slight chance of snow in the morning, then chance of snow and rain in the afternoon. Cloudy. Chance of snow in the evening then snow after midnight. Mostly cloudy. Chance of snow showers.
Temperatures: 40 to 46 deg. F. 22 to 27 deg. F. 33 to 38 deg. F.
Wind Direction: SW SW W
Wind Speed: 15 to 20mph with gusts to 35mph. 15 to 20mph with gusts to 40mph. 10 to 15mph with gusts to 35mph.
Expected snowfall: Trace to 2 in. 3 to 6 in. Up to 2 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Mostly cloudy. Slight chance of snow in the morning, then chance of snow in the afternoon. Cloudy. Chance of snow in the evening, then snow after midnight. Mostly cloudy. Chance of snow showers.
Temperatures: 37 to 43 deg. F. 19 to 24 deg. F. 28 to 34 deg. F.
Wind Direction: SW SW W
Wind Speed: 20 to 30mph. Gusts to 50mph increasing to 60mph in the afternoon. 20 to 35mph with gusts to 75mph. 15 to 25mph. Gusts up to 65mph decreasing to 40mph in the afternoon.
Expected snowfall: Trace to 2 in. 70% probability: 3 to 6 inches. 30% probability 7 to 12 in. Up to 2 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