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 January 26, 2013:


January 26, 2013 at 7:37 am

Pockets of MODERATE avalanche danger exist below treeline on N-NE aspects on slopes 37 degrees and steeper. For all other areas, avalanche danger remains LOW. Small loose wet snow avalanches remain possible in a variety of areas today due to recent rain on snow.


Forecast Discussion:


Once again snow levels were higher and rain amounts were greater than forecast over the past 24 hours. Through most of the day yesterday snow level ranged from 9,200' to above 9,600' with rainfall amounts of 0.2 to 0.8 inches. Ridgetop winds have remained light to moderate in speed out of the southwest. Some partial clearing is possible today between weather systems. The next weather system is expected to bring a cold front through the forecast area tonight, dropping air temperatures well below freezing for all elevations. Southwest ridgetop winds are forecast to increase to moderate to strong in speed this afternoon ahead of the approaching cold front.

Recent Observations:

Observations made yesterday on Elephant's Back (Carson Pass area), Tamarack Peak (Mount Rose area), and on Hidden Peak (West Shore Tahoe area) all revealed conditions indicative of the recent high snow levels and rainfall. Above 8,600' recent new snow amounts of 0.5 to 3 inches of snow were noted on trees. This new snow was then rained upon in most areas yesterday. Fog conditions with mist and light rain existed below snow level with freezing fog above snow level (photos, video, pit profiles, more info).

Wet surface snow 2 to 6 inches deep existed in all areas with the least supportable snow observed on Hidden Peak on N to NE aspects below 7,800'. In all areas roller balls and small wet loose snow avalanches were easily triggered on slopes steeper then 40 degrees. For the most part the well developed layer of near surface faceted snow crystals that existed at the snow surface below treeline on N-NE aspects below 8,000' has become moist with rain water. This is still a significantly lower density snow layer than the wet snow above it, allowing for the wet snow instability to occur up to 8 to 10 inches deep in areas where this snowpack structure exists. None of the observed or triggered loose wet snow avalanches were anywhere close to large enough to bury a person (photos, video, pit profiles, more info).

Air temperatures overnight have fallen below freezing at the upper elevations and in some mid elevation areas as well. Newly formed rain crust that ranges from breakable to supportable in expected today in areas above 7,800' to 8,500'. As the cold front moves through tonight, rain crust will form on all aspects at nearly all elevations.

Avalanche Problem #1: Loose wet avalanches

Human trigger small loose wet avalanches remain a concern for today on a variety of aspects. Steep N-NE aspects in below treeline terrain that are below 8,000' will hold the greatest hazard and size potential. Over the past two days, none of the observed loose wet snow avalanches have been large enough to bury a person, but areas with terrain traps present a greater hazard and could make burial possible.


The bottom line:

Pockets of MODERATE avalanche danger exist below treeline on N-NE aspects on slopes 37 degrees and steeper. For all other areas, avalanche danger remains LOW. Small loose wet snow avalanches remain possible in a variety of areas today due to recent rain on snow.


Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: 29 to 34 deg. F.
Max. temperature in the last 24 hours: 33 to 39 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: 30 mph
New snowfall in the last 24 hours: Snow 0 inches | Rain 0.2 to 0.8 inches
Total snow depth: 56 to 81 inches

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

For 7000-8000 ft:

  Saturday: Saturday Night: Sunday:
Weather: Partly to mostly cloudy skies with a slight chance of very light snowfall. Cloudy skies with a chance of snow. Cloudy skies with snow showers likely.
Temperatures: 34 to 39 deg. F. 16 to 21 deg. F. 21 to 26 deg. F.
Wind direction: SW SW SW
Wind speed: 10 to 20 mph increasing to 15 to 25 mph with gusts to 40 mph in the afternoon. 20 to 30 mph with gusts to 50 mph. 10 to 20 mph with gusts to 30 mph.
Expected snowfall: 0 to trace in. Up to 1 in. 1 to 3 in.

For 8000-9000 ft:

  Saturday: Saturday Night: Sunday:
Weather: Partly to mostly cloudy skies with a slight chance of very light snowfall. Cloudy skies with a chance of snow. Cloudy skies with snow showers likely.
Temperatures: 29 to 34 deg. F. 10 to 16 deg. F. 17 to 22 deg. F.
Wind direction: SW SW SW shifting to W
Wind speed: 20 to 30 mph with gusts to 50 mph, increasing to 30 to 40 mph with gusts to 70 mph in the afternoon. 35 to 45 mph with gusts 65 to 85 mph. 25 to 35 mph with gusts to 45 mph, decreasing to 15 to 25 mph with gusts to 35 mph in the afternoon.
Expected snowfall: 0 to trace in. Up to 1 in. 1 to 3 in.