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.


This Avalanche Advisory was published on December 10, 2012:


December 10, 2012 at 8:01 am

The avalanche danger remains LOW for all elevations and aspects. Continue to use normal caution when traveling in the backcountry. Icy slopes pose the greatest hazard by making long sliding falls that are difficult to control or arrest a real possibility today.


Forecast Discussion:


An inversion exists over the forecast area this morning with remote sensors showing temperatures in the high 20's below 7000 ft. and in the mountain valleys. Above 7000 ft. temperatures have warmed up some overnight, and remote sensors indicate temps in the mid 30's. The high pressure ridge should remain over the forecast area through tomorrow, and the northeasterly winds should start to decrease today and tonight. These two things will combine to allow more warming to occur over the next 24 hours. The forecast calls for today's highs to climb about 5 degrees higher than yesterday's and for tomorrow's highs to climb another 4-8 degrees. By tomorrow afternoon the winds should shift to the southwest and increase ahead of an approaching low pressure.

Recent Observations:

Yesterday on Lincoln Ridge (near Yuba Pass) and on Relay Peak (Mt. Rose backcountry) the snow surface consisted of a frozen rain crust at all elevations (photos from Lincoln Ridge and Relay Peak). This crust remains thick and supportable below 9200 ft and becomes more variable at the upper elevations. Below and on top of this surface crust a small layer of weak sugary snow has formed in many areas (snowpit from Lincoln Ridge, snowpit from Relay Peak). Below these facets another much thicker and stronger layer of frozen snow exists.

Avalanche Concerns:

Weak December sunshine and relatively cool daytime highs should not create enough melting for significant wet snow avalanche conditions to form today. Some softening may occur on the sun-exposed southerly aspects today due to daytime warming. Even though avalanche activity remains unlikely today the icy snow surface creates another potentially serious hazard. Falls on this kind of snowpack become much more likely and much more difficult to control or arrest. The ongoing faceting taking place between the top two rain crusts in the snowpack will be something to keep an eye on as future loading occurs.


The bottom line:

The avalanche danger remains LOW for all elevations and aspects. Continue to use normal caution when traveling in the backcountry. Icy slopes pose the greatest hazard by making long sliding falls that are difficult to control or arrest a real possibility today.


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature: 33-41 deg. F.
Max. temperature in the last 24 hours: 34-41 deg. F.
Average wind direction during the last 24 hours: Northeast
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: 50 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 34-46 inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:

  Monday: Monday Night: Tuesday:
Weather: Sunny Clear Sunny
Temperatures: 43-48 deg. F. 35-40 deg. F. 44-49 deg. F.
Wind direction: Northeast East Southwest in the afternoon
Wind speed: 10-15 mph with gusts to 25 mph 10-15 mph becoming light after 10 pm 0-10 mph in the morning increasing to 20-25 mph with gusts to 35 mph in the afternoon
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Monday: Monday Night: Tuesday:
Weather: Sunny Clear Sunny
Temperatures: 37-44 deg. F. 27-37 deg. F. 41-47 deg. F.
Wind direction: Northeast Northeast shifting to the West after midnight West shifting to the Southwest
Wind speed: 15-25 mph with gusts to 40 mph 15-20 mph with gusts to 30 mph 10-15 mph with gusts to 25 mph increasing to 30-35 mph with gusts to 55 mph in the afternoon
Expected snowfall: O in. O in. O in.

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