Dangerous avalanche conditions exist. Over the past two days, numerous skier triggered slides have been reported along with some natural activity. At the mid and upper elevations, skiers and riders are likely to trigger small to large wind slabs in steep, wind loaded terrain. Large persistent slab avalanches remain a concern. These slabs could be triggered directly by backcountry travelers or indirectly after stepping down from the release of a wind slab. Natural activity may remain possible. At the lower elevations, skiers and riders could trigger slab avalanches one to two feet in depth. Don’t let powder fever lure you into compromising terrain; expert snowpack evaluation and route selection skills will be essential for safe travel in avalanche terrain.
Since Wednesday, 12 to 16 inches of new snow has fallen in the Tetons. Southerly to northwesterly ridgetop winds accompanied this snowfall, and wind slabs with depths of one to two feet have formed in leeward terrain. These reactive wind slabs reside just above firm sun crusts, surface hoar and near surface facets. Today, these slabs will continue to be easily triggered on steep, wind loaded slopes.
Over the past two days, an inch to an inch and a half of snow water equivalent has been added to persistent weak layers of faceted snow that reside within the snowpack. Above 7,500 feet, this load has increased the likelihood of triggering dangerous slab avalanches with depths of two to four feet. The snowpack is comprised of mostly faceted snow below 7,500 feet. There, skiers and riders could trigger persistent slabs with depths of one to two feet.
The next in a series of Pacific weather systems will begin to move through the region Saturday night. This system is forecasted to favor the Tetons with up to a foot of new snow by midday on Sunday. During this time period, Togwotee Pass could see four to six inches, and only a few inches are expected in the Southwest Trails area. Ridgetop winds will back to the southwest at 20 to 30 miles per hour.On Sunday, dangerous avalanche conditions will continue, and the general avalanche hazard is expected to remain Considerable. New snow and wind will add depth and volume to the recently formed wind slabs. In steep, wind loaded terrain above 7,500 feet, skiers and riders could easily trigger these slabs with depths of 12 to 30 inches. The new snowfall will continue to load persistent weak layers of faceted snow deeper in the snowpack. These slabs, with depths of two to four feet, could be triggered directly by backcountry travelers or indirectly after stepping down from the release of a wind slab. Natural activity will be possible. Below 7,500 feet, skiers and riders could trigger slab avalanches one to two feet in depth. Don’t let the excitement of new snow impair your judgement; expert snowpack evaluation and route selection skills will be essential for safe travel in avalanche terrain.
