The areas with the greatest snow depths will have been subject to previous wind loading. These same areas will also have the greatest potential of an unstable wind slab type avalanche problem. Keep in mind that wind loading can increase snow deposition rates by 2 to 10 times the rate that snow is falling from the sky. Similar deposition rates can occur during periods of blowing snow under sunny skies. Either way, this rapid loading can create enough snowpack instability for an avalanche to occur, despite only a few inches of snow on the ground in wind protected areas. Basically, any areas with enough snow for over snow travel will also have avalanche concerns. Make constant observations as you travel, looking for indications of current or recent snowpack instability. The best indicator is recent avalanche activity. Other signs of snowpack instability including blowing or drifting snow, collapse, audible whumpfing sounds, shooting cracks, and/or test slope failure. These are all indications that the snowpack in the immediate area is unstable. When signs of an unstable snowpack exist, the only additional factors needed for avalanche to occur are a slope steeper than 30 degrees and a trigger (basically you).
The shallow snowpack this time of year does not eliminate the risk of avalanches. It does increase the likelihood of impact with rocks and subsequent injury either while caught in a small avalanche or while attempting over snow travel in general.
The high elevation snow that is starting to accumulate is building the basal snowpack layers in upper elevation avalanche terrain. Much of what is now accumulating will likely remain on shaded slopes. Aspects with more sun exposure may remain subject to melt. It will all depend on how the weather progresses this fall.
Current remote weather station data as well as a general weather forecast for the area provided by the NWS can be found by clicking here.
There is no time like to present to refreshing and expand your avalanche knowledge. At the awareness end of the spectrum, the Know Before You Go video is a great primer or reminder of how a few simple ideas can greatly expand the margin of safety for travel in avalanche terrain. Avalanche Canada's micro site on the "Rescue at Cherry Bowl" launches Nov 5 and will likely be trend setting in modern avalanche education. For something snowmobile specific, check out the Throttle Decisions video series. For more technical skills specific info, the Forest Service National Avalanche Center's webpage is a well put together online tutorial, direct and to the point, especially helpful if you are short on time but want something meaningful. To delve even deeper, Avalanche Canada's Online Avalanche Course is very well put together, offering excellent text, photos, videos, and even some interactive exercises. There is something of interest for every level and type of winter backcountry traveler. One could spend anywhere from 30 minutes to several hours on this course if you worked through all of the sub lessons and sub topics. The sections under "Reducing Risk in the Field" including the "Good Travel Habits" sub lesson on "Managing risk associated with different avalanche problems" are especially valuable for those who took a level one avalanche course more than 5 or so years ago.
When you are done with the online courses, check the Education link at the top of this page for a listing of providers for field based avalanche classes. There is no substitute for field based education and the opportunity to make real world, real time decisions with the guidance and feedback of a professional avalanche educator.
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.
For a recorded version of the Avalanche Advisory call (530) 587-3558 x258