Since yesterday afternoon, 7 to 8 inches of new snow has fallen and both wind speeds and temperatures have increased. Human triggered avalanches are possible today in terrain above 8000 feet where wind slabs have formed over weak snow surfaces and hard crusts. Loose snow sloughs in steep terrain are also possible. Below 8000 feet, unstable snow can be found on steep isolated terrain features. Use caution as moving snow can quickly sweep unsuspecting travelers into rocky terrain that is barely covered by the new snowfall.
Southwest to northwest winds have moved newly and recently fallen snow into leeward terrain forming soft slabs. These slabs could be triggered today with depths to two feet or greater, particularly in the northwest part of the Tetons where the most snow has fallen.
A transitory ridge will build over the region tonight. Then by early morning tomorrow, the upper-level flow is expected to back to the southwest as a Pacific cold front approaches Western Wyoming. Snowfall will develop from the south to the north and continue through tomorrow tapering off by the afternoon. Accumulations are expected to favor the Tetons with 4 to 6 inches and 2 to 4 inches are expected in the surrounding mountains. Mountain temperatures will start in the teens and warm into the twenties. Ridgetop winds will be westerly at 10 to 20 miles per hour with higher gusts. The avalanche hazard is expected to be Moderate above 8,000 feet in the Tetons and above 9,000 feet in the Grey’s River/Southwest Trails and Togwotee Pass/ Continental Divide forecast areas. As the new snow and moderate winds continue to load slopes and form slabs, it will be possible for backcountry travelers to trigger slab avalanches 1 to 2 feet deep. In areas where the new snow lies upon stout crusts or snow that lacks cohesion, these slides could entrain snow increasing in size. Backcountry travelers should assess slopes for wind loading and buried weak layers. At the mid and lower elevations in the Tetons, loose snow sluffing could easily gain momentum on steep slopes with significant vertical relief.
