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 February 5, 2013:

February 5, 2013 at 7:45 am

Avalanche danger remains LOW for all elevations and aspects. Normal caution is advised.

Forecast Discussion:

A weather system passing to the north of the forecast area today will bring an increase in high level cloud cover and ridgetop winds. This system will clear the region tonight. On Wednesday, clear skies will prevail in between weather systems. Maximum daytime air temperatures are forecast at 5 to 10 degrees colder for tomorrow than today. A return of snowfall is likely to occur on Thursday. Remote sensors are reporting air temperatures this morning in the upper 20s to low 30s above 8,000'. Maximum daytime air temperatures are forecast to warm into the mid 30s to mid 40s today for areas above 7,000'. Ridgetop winds out of the southwest increased to moderate in speed yesterday. Southwest winds are forecast to further increase to strong in speed as today progresses.

Recent Observations:

Observations made yesterday on Lincoln Ridge (Yuba Pass area) matched well with other recent observations from around the forecast area. Faceting processes are at work in the top 1 foot of the snowpack on many N and NE aspects above 7,200'. Near crust facets are fairly weak, but snowpit tests indicate that propagation is unlikely upon weak layer collapse. These weak layers are not an instability issue at this time, but warrant monitoring during future snow loading events (pit profile, more info).

Around the forecast area, snow surface conditions on N-NE aspects consist of 0.5 to 2 inches of dry, lightly faceted recent storm snow on top of supportable rain crust in near and below treeline areas with protection from NE winds. Areas with exposure to NE winds are scoured down to the most recent rain crust. Melt-freeze conditions are well established on SE-S-SW aspects. E and W aspects hold a mix of melt-freeze and dry snow conditions.

Avalanche Concerns:

Natural and human triggered avalanches remain unlikely today. Around an inch or so of wet surface snow formation is expected on SE-S-SW aspects in response to daytime warming. High level cloud cover and convective snow surface cooling by moderate to strong SW winds will reduce the overall amount of wet snow that forms today relative to recent days with clear skies and calm winds. Any form of wet snow instability is unlikely today. Other aspects are expected to remain frozen all day with widespread supportable crust conditions. Little to no snow is available for wind transport today, keeping slab avalanche activity unlikely.


The bottom line:

Avalanche danger remains LOW for all elevations and aspects. Normal caution is advised.


Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature: 28 to 33 deg. F.
Max. temperature in the last 24 hours: 43 to 50 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 22 mph
Maximum wind gust in the last 24 hours: 36 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 54 to 80 inches

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

For 7000-8000 ft:
  Tuesday: Tuesday Night: Wednesday:
Weather: Partly cloudy skies. Clear skies. Sunny skies.
Temperatures: 39 to 46 deg. F. 18 to 26 deg. F. 34 to 41 deg. F.
Wind direction: SW SW NW
Wind speed: 15 to 25 mph with gusts to 40 mph. 15 to 25 mph with gusts to 40 mph. Gusts decreasing to 30 mph after midnight. 10 to 15 mph.
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:
  Tuesday: Tuesday Night: Wednesday:
Weather: Partly cloudy skies. Clear skies. Sunny skies.
Temperatures: 35 to 42 deg. F. 20 to 26 deg. F. 26 to 33 deg. F.
Wind direction: SW SW shifting to W after midnight. W shifting to S in the afternoon.
Wind speed: 30 to 35 mph with gusts to 60 mph, increasing to 40 to 45 mph with gusts to 70 mph in the afternoon. 40 to 45 mph with gusts to 70 mph, decreasing to 25 to 30 mph with gusts to 50 mph after midnight. 15 to 20 mph with gusts to 35 mph.
Expected snowfall: O in. O in. O in.