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 October 27, 2012:


October 27, 2012 at 21:23 pm

Early season conditions update #2

We do not have enough information to issue regular avalanche advisories. We have started to collect data and will be sharing all of the information we gather on our observations page and in intermittent updates to this page. We plan to resume daily avalanche advisories in November as conditions dictate.


Forecast Discussion:


The snow from the recent storm continues to settle and melt. In some places it still provides supportable coverage; however, many barely hidden rocks, stumps, logs, and other bone-jarring, equipment-breaking obstacles lurk just under the surface. With careful route finding early season can provide fun recreation, but those obstacles and a shallow snowpack also make it more serious even when the avalanche danger decreases.

Earlier this week observations showed that the wind slabs that formed on wind loaded slopes both near treeline and above treeline did fail naturally and in response to human triggers. Observations over the last few days have shown a more stable and "right-side up"  (lighter snow on top of more dense snow) snowpack in most places. As the snowpack continues to settle, consolidate, and melt the avalanche concerns should continue to diminish.

The forecast calls for another small storm to reach the region by mid week. The additional snow and wind associated with this storm could create new instabilities including storm slabs and wind slabs. These slabs will form on top of a snowpack that has covered some of the anchors that typically hold early season snow in place. Expect to see avalanche issues increase as this next storm impacts the area.

When traveling in the backcountry continue to make constant observations and look for indications of current or recent snowpack instability. The best indicator is recent avalanche activity. Wind loading, collapse, audible whumpfing sounds, shooting cracks, and/or test slope failure also represent excellent indications that an unstable snowpack exists in the immediate area. Once an unstable snowpack has formed, the only additional ingredients to create an avalanche are a slope steeper than 30 degrees and a trigger.

If you plan to embark on some early season adventures in or near avalanche terrain, each person should travel with avalanche rescue equipment including a transceiver, probe, and shovel with which they are well practiced. Allow only one person at a time to travel on slopes that are steeper than 30 degrees. Also remember those many hazards such as rocks, down trees, and stumps that lie hidden just beneath the snow surface. An injury at this time of year can make for a very long winter. Some great ways to enjoy the early season snow include practice rescue skills and beacon searching while out touring on snow covered forest roads or making turns on a slope where you know the snow is sitting on top of a soft grassy meadow.

Check out the avalanche tutorials specifically designed for skiers and snowmobilers at the Forest Service National Avalanche Center web site.

Current remote weather station data from the NWS can be found by clicking here. A general weather forecast for the area can be found by clicking here.

Please note: If you are intending to travel within the boundaries of a ski area that is not yet open for the season, no avalanche mitigation measures exist at this time. Please treat any closed ski area as the backcountry terrain and snowpack that it currently is. Respect any closure signs that may be in place at the parking lot or base area. Carry proper backcountry equipment and avalanche rescue equipment. Expose only one person at a time to avalanche terrain (which is often widespread and complex within a ski area). Do not traverse above others. Things may look the same and seem very familiar to an operating ski area, but from a safety standpoint, right now the avalanche risk is significantly higher.


The bottom line:

Early season conditions update #2

We do not have enough information to issue regular avalanche advisories. We have started to collect data and will be sharing all of the information we gather on our observations page and in intermittent updates to this page. We plan to resume daily avalanche advisories in November as conditions dictate.


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: deg. F.
Max. temperature in the last 24 hours: deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: O inches
Total snow depth: inches

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

For 7000-8000 ft:

  Saturday: Saturday Night: Sunday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Saturday: Saturday Night: Sunday:
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind direction:
Wind speed:
Expected snowfall: O in. O in. O in.