Approximately two feet of snow has fallen in the Southwest Trails area during the last three days. Dangerous avalanche conditions exist in the backcountry. Human triggered avalanches are likely and natural avalanches are possible at all elevations today. The chance exists for skiers and riders to trigger both recently formed wind slabs or larger slabs involving old buried weak layers. Caution is advised and riders and skiers are urged to consider not only their own safety but also that of the rescuers and loved ones at home. Conservative decision making and avoiding steep avalanche terrain altogether is recommended, especially if not properly equipped with proper rescue gear and training. Several slides occurred in the Teton area yesterday, one involved an injured skier who was rescued from very dangerous terrain.
Southwest winds have created new wind slabs up to three feet in depth at the higher elevations and to eighteen inches in depth at the lower elevations. Natural avalanche activity is possible and human triggered avalanches are likely on a variety of aspects at all elevations.
Buried layers of faceted snow exist in the snowpack. Large persistent slab avalanches could fail on these layers with depths from 2 to 4 feet at the higher elevations and 2 feet at the lower elevations. These dangerous slab could fail naturally or be triggered by the weight of a single person or the release of a surface slab.
( Discussion is generated from the previous day's afternoon forecast. )Cold air will move in tonight and bring temperatures to the low single digits by sunrise at all elevations. Daytime highs are forecast to the near ten in the mountains and the upper teens in the valleys. Winds are to veer to the northwest with five to fifteen mile per hour averages. Given the forecast temperatures and moderate to light winds the avalanche danger is expected to be Considerable at all elevations and in all forecast areas. The likelihood of slabs releasing naturally is expected to decrease however DANGEROUS conditions will continue as it will remain likely for a skier or rider to trigger potentially large slides in steep avalanche terrain on any aspect. Slab depths could reach as much as four feet and are most likely to fail on the interface between the recent snow the layer that was buried on Saturday although other weaknesses deeper in the snowpack exist and could also fail or simply be entrained in a moving slide. Check the morning forecast and monitor conditions in the field as the hazard could increase to High if sunshine allows temperatures to spike higher than currently forecast or if the winds are stronger than anticipated. The light snow that fell during generally consistent southwest winds will be very susceptible to transport by northwest winds and could quickly load steep slopes in different areas, causing natural releases.
