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 10, 2012:


February 10, 2012 at 7:45 am

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


Forecast Discussion:


Transitional weather will occur today as a series of weak to moderately strong weather systems approach the forecast area. Sunny skies this morning will give way to increasing cloud cover throughout the day. Very light precipitation is possible starting late this afternoon or evening. Increasing southwest winds last night kept any air temperature inversion from forming this morning. Remote sensors are reporting air temperatures in the 8,000' to 9,700' range in the upper 20s to upper 30s this morning. Air temperatures between 6,000' and 8,000' are in the 30s and 40s this morning. Maximum daytime air temperatures are forecast to reach the mid 30s to mid 40s today for areas above 7,000'. Moderate to strong southwest winds will continue through tonight, before becoming light tomorrow afternoon. Air temperatures for Saturday will be cooler than today, with highs in the 20s and 30s expected. New snow accumulations over the next two days will likely limit to trace amounts, with up to 2 inches possible in the best case scenario.

Recent Observations:

Observations made yesterday on Mount Houghton (Mount Rose area) and on Mt. Tallac (Desolation Wilderness area) continued to show the trend of a stable snowpack (photos, pit profiles, more info). Air temperatures warmed well above freezing, creating 2 to 5 inches of wet snow on SE-S-SW aspects during the mid day and afternoon hours. Melt freeze conditions extended to most sun exposed areas and all low elevation areas, creating a new thin surface crust in areas without well established melt freeze conditions. The surface snow on shaded northerly aspects at the mid and upper elevations remained cold and dry. In general across the forecast area, NW-N-NE aspects hold stable and well anchored snow in the lower and middle portions of the snowpack. Near surface faceting to various degrees exists within the top 1 foot of the snowpack. The surface or near surface rain crust that formed after the January 26 rain event continues to become increasingly brittle on northerly aspects. Faceted snow exists below this crust, but no significant slabs exist on top of this crust/facet combo. Mostly clear skies last night are expected to have allowed for wet surface snow to refreeze last night due to radiational cooling, despite the near to above freezing air temperatures in many areas.

Today's Avalanche Concerns:

A couple of inches of wet snow are expected to form today on SE-S-SW aspects at nearly all elevations. Just how much wet surface snow forms will be highly dependent on the rate at which cloud cover builds. Areas of significant wet snow instability are not expected. On NW-N-NE aspects, no significant changes in the stability of the snowpack are expected to occur today from what has been observed over the past week. Natural and human triggered avalanche activity remains unlikely today on all aspects and at all elevations.


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: 29 to 34 deg. F.
Max. temperature in the last 24 hours: 42 to 50 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 23 mph
Maximum wind gust in the last 24 hours: 47 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 19 to 34 inches

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

For 7000-8000 ft:

  Friday: Friday Night: Saturday:
Weather: Sunny skies in the morning, becoming partly cloudy. Mostly cloudy skies with a slight chance of snow showers. Mostly cloudy skies with a chance of snow showers in the morning. Partly cloudy skies with a slight chance of snow showers in the afternoon.
Temperatures: 41 to 47 deg. F. 24 to 29 deg. F. 33 to 38 deg. F.
Wind direction: SW SW SW
Wind speed: 15 to 25 mph with gusts to 40 mph. 15 to 30 mph with gusts to 45 mph. 10 to 15 mph with gusts to 25 mph in the morning, becoming light.
Expected snowfall: O in. 0 to trace in. 0 to 1 in.

For 8000-9000 ft:

  Friday: Friday Night: Saturday:
Weather: Sunny skies in the morning, becoming partly cloudy. Mostly cloudy skies with a slight chance of snow showers. Mostly cloudy skies with a chance of snow showers.
Temperatures: 35 to 42 deg. F. 20 to 25 deg. F. 27 to 33 deg. F.
Wind direction: SW SW SW to W
Wind speed: 25 to 40 mph with gusts to 65 mph. 25 to 40 mph with gusts to 60 mph. 25 to 30 mph with gusts to 45 mph, decreasing to 10 to 20 mph in the afternoon.
Expected snowfall: O in. 0 to trace in. 0 to 2 in.