Both natural and human triggered avalanches occurred yesterday, and avalanche conditions remain dangerous. Another cold front moved through last night, and temperatures are starting out 10 to 15 degrees cooler than yesterday morning. Skiers and riders could easily trigger small to large wind slabs in steep, wind loaded terrain. Large to very large persistent slab avalanches remain a threat. One of these slabs recently released naturally in the north fork of Phillips Canyon in the Southern Tetons at an elevation of 10,000 feet. This very large avalanche involved most of the bowl with aspects ranging from the southwest to the southeast. The crown depth was reported to be six feet, and being caught in a similar slide would be unsurvivable. Don’t let abundant powder and the holiday weekend impair your judgement; conservative terrain choices will be essential for safe travel in avalanche terrain.
Abundant snowfall and southwesterly ridgetop winds have formed wind slabs in leeward terrain. At the mid and upper elevations, skiers and riders are likely to trigger these slabs with depths of one to four feet in steep, wind loaded terrain. These slabs might still release naturally.
As the recent avalanche event in Phillips Canyon illustrates, deadly persistent slab avalanches with depths of two to six feet remain a threat. These slabs could fail on buried layers of faceted snow that formed on the surface. At the lower elevations, where basal facets exist in the snowpack, these slabs could fail to the ground. These slabs could be directly triggered by backcountry travelers or step down from the release of a wind slab. Natural activity may still be possible.
Periods of light snowfall and cloud cover will continue on Sunday. The cooling trend will also carry on with overnight mountain lows near zero degrees. Afternoon highs will be near 10. Westerly to southwesterly ridgetop winds will range from 10 to 20 miles per hour.Saturday’s avalanche events are a stark reminder that dangerous avalanche conditions exist, and the general avalanche hazard is expected to remain Considerable on Sunday. While the likelihood of triggering slides is slowly decreasing, the potential for very large, unsurvivable persistent slab avalanches will continue. Recently developed winds slabs, with depths of one to three feet, should also not be taken lightly. Skiers and riders will continue to be able to trigger both of these types of avalanches. Persistent slab avalanches could also step down from the release of a smaller wind slab. While the abundant recent snowfall is very enticing, it is not worth dying for. Great skiing and riding can easily be found in conservative terrain.
