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 26, 2011:


December 26, 2011 at 8:03 am

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


Forecast Discussion:


Expect another warm and mostly sunny day over the forecast area. Some clouds should start to develop and the southwest winds should increase as a small low pressure passes north of the region. By tonight the forecast calls for mostly cloudy skies and winds reaching into the 40 mph range along the Sierra Crest. This system should move out of the area by tomorrow, and the winds should subside. Some cloud cover could linger over the region. Warmer than normal temperatures should also remain over the forecast area for the next several days. Daytime highs for today and tomorrow should reach into the low to mid 40's above 7000 ft.

Observations:

Observations on Mt. Judah yesterday still indicated that all of the layers in the snowpack continue to weaken and facet despite the recent warmer weather (snowpit). The warmer weather combined with scouring by almost a month of N-NE-E winds has caused even more snow to disappear from the already meager snowpack. Across the forecast area on the NW-N-NE-E aspects, the snowpack remains shallow and weak where ever snow exists (photo). In most of these areas, the snowpack consists only of weak snow with no slab on top of it. In most of the isolated areas where a slab does remain on top of the snowpack, observations have shown that either enough anchors extend through the snowpack to hold everything in place or the the slabs remain strong enough to support themselves. The SE-S-SW-W aspects remain dry and rocky except for a few patches of snow in shaded areas (photo).

Avalanche Concerns: Persistent slabs

Avalanche activity remains unlikely because the weak snowpack still has almost no slabs sitting on top of it. The slabs that do still exist usually have enough anchors protruding through the snowpack to hold them in place. In most places a stable snowpack exists and signs of instability remain hard to locate. A few isolated areas on steep northerly slopes that do not have very many anchors could still hold small pockets of possible instability. Snowpit tests can indicate the slopes where these rare patches of instability may remain. Any observations that point towards an unstable snowpack should trump all signs of stability. Continue to travel with caution in the backcountry and evaluate slopes on an individual basis.  


The bottom line:

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


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: 32-36 deg. F.
Max. temperature in the last 24 hours: 37-45 deg. F.
Average wind direction during the last 24 hours: West southwest
Average wind speed during the last 24 hours: 20-30 mph
Maximum wind gust in the last 24 hours: 37 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 4-20 inches

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

For 7000-8000 ft:

  Monday: Monday Night: Tuesday:
Weather: Partly cloudy Mostly cloudy Mostly cloudy
Temperatures: 38-45 deg. F. 18-25 deg. F. 37-44 deg. F.
Wind direction: Southwest Southwest Southwest
Wind speed: 10-15 mph with gusts to 35 mph in the afternoon 10-15 mph with gusts to 40 mph around 15 mph with gusts to 30 mph
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Monday: Monday Night: Tuesday:
Weather: Partly cloudy Mostly cloudy Mostly cloudy
Temperatures: 39-45 deg. F. 19-26 deg. F. 37-43 deg. F.
Wind direction: Southwest Southwest West
Wind speed: 20-30 mph with gusts to 50 mph 30-40 mph decreasing to 20-35 mph with gusts to 55 mph after midnight 15-20 mph with gusts to 35 mph
Expected snowfall: O in. O in. O in.