Riders and skiers have the potential to trigger slab avalanches today. Soft slabs formed during snowfall in January could slide in very steep, wind loaded terrain at all elevations. Above 7500 a slight chance may remain for failure of weak snow layers deep in the snowpack. Careful snowpack and terrain evaluation followed by thoughtful decision making is essential today.
Recent snow and strong winds have formed soft slabs in the backcountry. These slabs lie on a variety of snow surfaces that developed during a dry period between Christmas and January 5th. Slab depths range from one foot at lower elevations to three feet at the higher elevations. These slabs could fail from the presence of a single person in very steep terrain that is prone to wind loading.
Above 7,500 feet, hard slabs with depths to six feet lie upon persistent weak layers. Approximately 5 inches of moisture was recently added to the snowpack. During this loading, the only activity on this layer was on paths that had released before Christmas and slides above our forecast elevations in the Tetons. The last deep slab in the forecast zone was on January 2nd. Although activity on this layer is unlikely, if triggered, these slabs would carry severe consequences.
Steady snowfall will continue through midnight before becoming intermittent during the day on Sunday. Overnight lows in the mountains will be in the upper teens before rising back into the low 20s in the afternoon. Southwesterly ridgetop winds will veer to the northwest at 20 to 30 miles per hour.The general avalanche hazard is expected to be Moderate on Sunday. Skiers and riders venturing into steep, wind loaded avalanche terrain could trigger newly developed soft slabs six to twelve inches deep. Some chance persists to trigger deeper slabs that formed during the last storm cycle. These slides could be up to three feet deep. Faceted snow near the base of the snowpack remains a concern in the Togwotee Pass area. In the Tetons and the Greys River area, a very slight chance persists for avalanche activity on these basal facets.
