Very dangerous avalanche conditions exist and human triggered avalanches are likely today at the mid and upper elevations. 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. At low elevations, the old weaknesses are not present and avalanche activity could be triggered as shallow surface slabs in very steep terrain.
Strong winds from the southwest to west occurred yesterday afternoon during heavy snowfall and during snowfall over the past week. Above 7500 feet, 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. These weaknesses will be further stressed as additional snow falls today. These slabs could release by the weight of a single person. If triggered, these will be hard slabs and could have depths to five feet.
Some snow is expected overnight before tapering off on Christmas. Highs are to be in the low teens and southwest to west winds are to be light.The avalanche hazard is expected to be Considerable. Surface slabs to two foot depths could be triggered in steep terrain. Larger, dangerous slabs that could occur due to failure deeper in the snowpack remain possible to likely depending on location. These slabs could have depths to five feet in the Tetons and to two feet in the Togwotee Pass and Southwest trails areas.
