Two types of avalanche problems await backcountry travelers today. Soft wind slabs formed by recent snow and strong winds lie at all elevations. The possibility also exists to trigger very large and dangerous avalanches involving deeply buried weak layers on certain aspects above 9000 feet. Evaluate the snowpack and terrain carefully to avoid these avalanche concerns. 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.
Above 9000 feet, deep hard slabs continue to be a concern on northwest to northeast aspects. A single skier or rider could impact this persistent weak layer and trigger a very large, hard slab avalanche with depths to five feet. Large triggers, such as snowmobiles, are more likely to cause failure of this weak layer.
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 up to three feet.
( Discussion is generated from the previous day's afternoon forecast. )Inversion conditions and patchy fog are expected Friday morning. Mountain temperatures should be near ten degrees in the morning, with valley temperatures below zero. By noon temperatures should reach the upper teens to low twenties under mostly clear skies. At that point an upper lever trough moving from the west to southeast, combined with arctic air, should bring snowfall to the area by evening. This snowfall should continue through most of Friday night. The general avalanche hazard in the Tetons will be Moderate at the mid and high elevations, and Low at the low elevations. In the Togwotee Pass and Southwest Trails areas, the rating will be Considerable above 9000 feet, and Moderate below that elevation. Although the ratings vary, the avalanche problems are generally the same in all areas. Weak snow near the base of the snowpack persists on west, north and east aspects above 9000 feet. A single rider or skier could still trigger large and dangerous avalanches involving this layer in all forecast areas, although they are less likely to be triggered in the Teton area, mainly due to greater snow depths. Additionally, wind slabs to two feet could be triggered in steep, wind-loaded terrain.
