Dangerous conditions exist at the upper elevations and heightened avalanche hazards exist at the mid and lower elevations. The Teton area has received five feet of new snow this week and up to 13 feet of new snow in the past three weeks. Instabilities are present on steep avalanche prone slopes. Yesterday two people were caught and partially buried on a southeast aspect of Prospector Mountain and a large slab avalanche was triggered by a snowmachine on a southeast aspect northeast of Ski Lake. Avalanche fatalities occurred on Togwotee Pass yesterday and in the Salt River Range on Wednesday. At least 12 people have been caught in avalanches in Western Wyoming since Sunday. Twenty-two people have died in avalanches in the United States since January 30. Large to very large slab avalanches could be triggered by humans or release naturally today. These events could occur on a variety of aspects. In the Teton Range multiple large avalanches have recently occurred on southeast aspects. Expert terrain and snowpack assessment skills are essential for safe travel in avalanche terrain today.
Persistent slab avalanches could be human-triggered at the lower elevations and at the mid and upper elevations in areas with shallower snow depths, where layers of faceted snow persist in the snowpack. These persistent slabs are likely to range in depth from 2 to 5 feet, and could also be triggered by the release of a wind slab.
Soft wind slabs formed by southwest to northwest winds could be triggered today on steep avalanche prone slopes. These are likely to fail on density differences in the new snow or on a more deeply buried wind packed snow surface and sun crusts on solar aspects. These slabs could be one to five feet deep.
In a westerly flow, pacific disturbances are expected to bring moisture to the forecast area tonight and into tomorrow. Snowfall should increase overnight with 8 inches in the Tetons and 5 inches in the other forecast areas by the morning. Then tomorrow steady snowfall is expected to last into the afternoon. Mountain temperatures should range from 10 to 20 degrees and westerly to northwesterly ridgetop winds will be 15 to 30 miles per hour. Dangerous avalanche conditions exist in all the forecast areas. The hazard is expected to be Considerable and depending on the intensity of the storm could increase to High in some areas. In steep avalanche terrain, backcountry travelers could easily trigger slab avalanches 3 to 6 feet deep, and natural avalanches will be possible. Although the deep slab avalanches are the main concern, newly formed surface slabs will likely develop on leeward slopes and if triggered could initiate the failure of a large slide. It will be important to monitor conditions and wise to avoid avalanche terrain.
