Very strong south winds and significant accumulations of heavy snow overnight created HIGH avalanche danger on drifted upper elevation slopes in the backcountry.
Very dangerous avalanche conditions exist, and avalanches of wind drifted snow are likely in exposed terrain. People are likely to trigger soft slab avalanches of storm snow, even in more sheltered terrain, and natural avalanches are most likely during periods of particularly heavy snowfall and/or wind loading. The danger will continue to rise and become more widespread as the powerful winter storm continues.
People are likely to trigger slab avalanches of wind drifted storm snow if they venture onto exposed upper elevation slopes. Triggered avalanches will also be possible on drifted mid and lower elevation slopes, especially as the storm progresses and more snow falls down low.
The danger of loose and soft slab avalanches of storm snow will increase as heavy snow stacks up on steep slopes. Natural avalanches will become possible on upper elevation slopes during periods of intense precipitation. Avalanches of storm snow are possible in sheltered terrain and on smooth mid elevation slopes with significant accumulations.
No avalanches were yet reported but several parties triggered collapses (or whumps) in lower angle terrain over the weekend. Audible collapses are a red flag signals indicating unstable snow.
It's game on! Looks like 19 inches of new snow accumulated last night up at the 8400' Tony Grove Snotel, with 2.8" of SWE and 39" of total snow. The National Weather Service has continued a Winter Storm Warning through 11:00 Thursday morning. Significant heavy snowfall and drifting will continue to cause dangerous avalanche conditions in the backcountry. Temperatures are expected to cool and the rain-snow line is expected to gradually drop to the valley floors.
Shallow early season snow conditions exist, with about a foot-and-a-half of total snow covering the rocks on most upper elevation slopes before last night's snow. Extreme caution is required to avoid hitting shallowly buried rocks, stumps, or down trees.
The Tony Grove Road is not maintained for wheeled vehicles in the winter, and you are likely to encounter unimproved winter driving conditions as snow piles up with this storm.
Please submit your observations from the backcountry HERE.
For information on where you can ride your sled or snowbike, check out this map of the winter travel plan for the Tony Grove and Franklin Basin Areas HERE.
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.
