Very dangerous avalanche conditions exist and human triggered avalanches are likely today above 7500'. Snow has fallen for fifteen days on snowpack with weak snow at its base. Avalanches could be triggered today on these deep weaknesses and smaller avalanches are also possible involving newer snow that has recently fallen. This recent snow could release as wind slabs or as loose snow, particularly in areas that received over twenty inches of snow yesterday. Below 7500', the old weaknesses are not present and avalanche activity could be triggered as shallow surface slabs in very steep terrain.
New snow and wind continue to load a snowpack with poor structure that is unstable. Large human triggered slab avalanches with depths from two to four feet are likely to be triggered in steep terrain above an elevation of 7,500 feet. These dangerous slabs will fail on buried layers of faceted snow and could propagate long distances across terrain barriers.
New surface slabs up to two feet in depth could be human triggered on steep avalanche prone slopes. These slabs were formed by west to southwest winds and at the mid and upper elevations could step down into weak old snow layers.
( Discussion is generated from the previous day's afternoon forecast. )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.
