Two types of avalanche problems await backcountry travelers today. Soft wind slabs formed by recent snow and strong winds lie at the mid and high elevations. The possibility also exists to trigger very large and dangerous avalanches involving deeply buried weak layers on certain aspects at the high elevations. Evaluate the snowpack and terrain carefully to avoid these avalanche concerns. At low elevations, avalanches are unlikely except for in isolated pockets of shallow soft slab. Yesterday, searchers using rescue dogs at Grand Targhee located the body of the person who went missing on December 23rd. It is believed that he was buried after being swept over a significant cliff when a cornice failed and triggered a surface slab.
Recent snowfall and strong south-southwest to west winds have formed soft slabs in steep leeward slopes near ridgelines and under cliff areas where drifting snow accumulates. These slabs could be triggered in very steep terrain with depths of one to three feet.
Above 9000 feet, deep hard slabs with depths to six or possible eight feet continue to be a concern on west through north to east aspects. Although the likelihood of triggering one of these instabilities has lessened, make no mistake that the weakness remains present and failure is still possible to larger triggers such as snow machines or if a weak trigger point is crossed. If triggered, surviving one of these very large hard slab events is unlikely.
The stream of Pacific moisture will bring a few inches of new snow overnight before tapering off by morning. Cloud cover will then decrease during the day. Overnight lows in the mountains will drop into the single digits before rising into the mid teens in the afternoon. Westerly to northwesterly ridgetop winds will range from 15 to 25 miles per hour.The general avalanche hazard is expected to be MODERATE in the Tetons and Greys River forecast zones on Saturday. There, backcountry travelers might still be able to trigger a deep persistent slab in terrain that held snow from early October. Large triggers, such as snowmobiles, are more likely impact this basal weak layer. Skiers and riders could also trigger wind slabs to depths of three feet in steep, wind-loaded avalanche terrain above 7,500 feet.In the Togwotee Pass area, where the snow depths are shallower, the general avalanche hazard is expected to remain CONSIDERABLE due to the increased likelihood of triggering a deep persistent slab. Wind slabs, similar to those in the other forecast zones, will also be a problem of concern.
