Dangerous avalanche conditions exist. Large human triggered avalanches are possible at the mid and upper elevations and could run long distances into lower elevation run-out zones. Smaller pockets of wind slab could also be triggered by humans in very steep terrain at the lower elevations. Expert terrain evaluation and snowpack stability assessment skills are essential for safe travel in avalanche terrain.
New surface slabs formed by west to southwest winds could be human triggered in steep avalanche starting zones. At the mid and upper elevations these slabs could be one to three feet deep and have potential to steep down to deeper layers of faceted snow. At the lower elevations pockets of surface slab could be human triggered in very steep terrain with depths to 18 inches.
Weak layers of faceted snow near the base of the snowpack have been loaded by snow and wind during the past several weeks. Todays snow and wind will continue to increase that load. At the mid and upper elevations dense slabs with depths of three to five feet could be triggered by the weight of a single person in steep avalanche terrain on a variety of aspects.
Although snowfall is to continue through Thursday, the intensity should decrease tonight as temperatures lower and winds decrease. Temperatures in the single digits are expected in the early morning and highs should reach the teens in the mountains. Winds are to be southwesterly with twenty to thirty mile per hour averages in the morning, decreasing in the afternoon. If significant snowfall occurs overnight, the avalanche hazard will be High in all the forecast areas. Avalanches could occur as surface wind slabs or they could involve deep persistent weak snow. These older weaknesses could result in large hard slab avalanches with depths to two feet in the Togwotee Pass and the Southwest Trails areas, and depths to five feet in the Tetons.
