During the past two days, there have been several near-misses with skiers triggering surface slab avalanches in step, cliffy terrain. Today it is possible for backcountry travelers to continue to trigger these winds slab avalanches, especially in steep, wind loaded terrain. These slides are large enough to injure or bury a person. The deep persistent slab avalanche is unlikely to trigger but remains a concern. The general avalanche hazard below 7,500 feet in low.
Yesterday, strong northwest to north winds loaded leeward slopes at the upper elevations. Backcountry travelers triggered these wind slab avalanches on steep, rocky slopes. These slabs have been 1 to 2 feet in depth and will be more easily triggered as the day warms.
Although unlikely, a chance still exists to trigger deep hard slabs involving weak snow near the base of the snowpack. If triggered, these slabs could have crown depths of 3 to 7 feet. Areas where a thin snowpack exists or larger triggers, such as a cornice drop, a moving wind slab or a snowmachine, may be required to trigger such an event. Involvement in one of these slides would likely be fatal.
On Saturday, skies will be partly cloudy to mostly sunny as warm air advects into the region from the southwest. Mountain temperatures may warm slightly overnight before climbing into the mid-30s in the afternoon. Westerly ridgetop winds will increase to 20 to 30 miles per hour.The general avalanche hazard is expected to be Moderate above 7,500 feet on Saturday. Skiers and riders could trigger recently developed wind slabs ranging in depth from one to two feet in steep, wind loaded terrain. As the day warms, these slabs may become more susceptible to failure on sunlit aspects. Daytime warming and sunshine could also bring about the possibility of shallow wet slides. Monitor temperatures and the sun’s impact on snow surfaces, and transition to shaded terrain if snow surfaces start to become damp. The low probability/high consequence event of triggering a persistent deep slab avalanche still warrants mention. In the Teton and Southwest Trails forecast zones, these slabs could range in depth from three to seven feet. On Togwotee Pass, they could vary from two to four feet deep. Below 7,500 feet, the snowpack is mostly stable, and avalanches are unlikely.
