Avalanche conditions continue to be dangerous at the mid and upper elevations. Although a slight chance remains to trigger wind slabs formed during the last storm, the primary concern lies with the deeper persistent slab problem that involves weak snow that was buried on December 11th. Cautious route finding is essential today as the deep problem is widespread and it is becoming increasingly difficult to predict which slopes may or may not fail. The best course of action is to avoid steep avalanche prone terrain. Below 7500 feet, avalanches are unlikely today except in steep isolated terrain features.
Avalanches involving weak faceted snow and crusts that formed in early December could be human triggered today. These slabs are likely to be hard and could have depths to four feet. In some areas, these slabs have become less sensitive to triggers which can be misleading as a slope can still fail to the weight of a single person, even after it has been tracked.
Winds that were from the southwest to west during Saturday's storm and from varying directions since have formed slabs on the surface of the snowpack in terrain above 8500 that is prone to wind loading. These soft slabs could be triggered on steep loaded terrain features with depths to eighteen inches.
As pacific moisture moves into the region, light snowfall will develop overnight and continue into tomorrow. The snowfall is expected to favor the Tetons with three to six inches of accumulation and only one to three inches across the rest of the forecast area. Mountain temperatures will start in the single digits and then rise into the teens. Southwesterly winds will be light and veer to the west and then north by the evening. Above 7,500 feet in the Grey’s River/Southwest Trails and Teton forecast areas, dangerous large to very large slab avalanches could be triggered by skiers and riders, and the avalanche hazard is expected to remain Considerable. These slabs could be three to four feet in depth and lie over a variety of weak faceted snow. At Togwotee Pass, where there has been less snow this season, it is possible for skiers and riders to trigger persistent slab avalanches one to two feet in depth on steep, avalanche-prone terrain. Since these problem layers lie deep in the snowpack, slopes could present as stable, and tracks should not be trusted as signs of stability. Along high ridgelines and wind loaded terrain features, backcountry travelers could encounter small wind slabs that have recently been formed. Cautious route finding is essential to travel through the mountains and monitor the new snow as it increases the load on existing weak layers. Below 7,500 feet, where avalanches are unlikely except for on isolated terrain features, the avalanche hazard is Low.
