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 8, 2012:


January 8, 2012 at 7:50 am

LOW avalanche danger exists for all elevations and aspects. Use normal caution in the backcountry.


Forecast Discussion:


Spring-like weather should return to the forecast area today as a high pressure ridge rebuilds over the region. The north and east winds should decrease today, and by tomorrow winds should become light at all elevations. Temperatures should also climb back into the low to mid 40's above 7000 ft today with even warmer daytime highs forecasted for tomorrow. A few high, thin clouds may linger over the forecast area during the day today, but these should disperse by this afternoon and evening leaving skies clear for tonight and tomorrow.

Observations:

A highly variable snowpack exists across the forecast area. Observations since the rain event on Dec. 28-29 area have shown a mostly stable snowpack with thick, strong melt-freeze layers and rain crusts holding everything together. In the areas where less rain fell (mostly south of Barker Pass, on the east side of the Lake, and at the higher elevations), some weaker facets still remain underneath the rain / melt freeze surface crusts. Luckily less snow exists, and more anchors protrude through the snowpack in these areas. Above 9000 ft where less rain and warming have occurred strong north and easterly winds earlier this fall and winter have scoured most of the snow away from these once worrisome starting zones. Yesterday on Round Top Peak and around Carson Pass, very little snow existed below 9000 ft. Above 9000 ft on the northerly aspects, patchy snow coverage existed mostly due a lack of snowfall and the wind scouring mentioned above. The largest snow patches consisted of very dense, icy snow left over from last year. In some of the more sheltered areas, the snowpack consisted of a thick, strong hard slab with weaker snow below it. Snowpit tests in these areas indicated that fractures can travel through this weak layer; however, starting such a fracture remains difficult.

Avalanche Concerns:

Avalanche activity remains unlikely. In most places the persistent weak layer that plagued the area for most of the season has gained strength due to the recent rain and warmer weather. In the areas it still remains, enough anchors extend through the snowpack to keep the snow that exists in place. The recent cold, clear nights and colder days have allowed some weakness to reform in the snowpack; however, these weaknesses remain isolated and dispersed in nature. If they continue to grow, they could create weak layers that may pose problems later on. Even though the avalanche danger remains low, plenty of other hazards like icy slopes with rocks and trees at the bottom exist. Continue to use caution when traveling in the backcountry.


The bottom line:

LOW avalanche danger exists for all elevations and aspects. Use normal caution in the backcountry.


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: 26-34 deg. F.
Max. temperature in the last 24 hours: 28-34 deg. F.
Average wind direction during the last 24 hours: Northeast
Average wind speed during the last 24 hours: 48 mph
Maximum wind gust in the last 24 hours: 77 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 0-18 inches

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

For 7000-8000 ft:

  Sunday: Sunday Night: Monday:
Weather: Mostly sunny Clear Sunny
Temperatures: 40-45 deg. F. 26-33 deg. F. 45-50 deg. F.
Wind direction: East Southeast South
Wind speed: 10-15 mph with gusts to 30 mph decreasing in the afternoon up to 10 mph up to 10 mph
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Sunday: Sunday Night: Monday:
Weather: Mostly sunny Clear Sunny
Temperatures: 37-44 deg. F. 28-33 deg. F. 40-46 deg. F.
Wind direction: East East Southwest
Wind speed: 15-25 mph with gusts to 50 mph in the morning decreasing to 10 -15 mph with gusts to 35 mph 10-15 mph with gusts to 30 mph around 10 mph
Expected snowfall: O in. O in. O in.