Layers of persistent weak snow lie hidden within the snowpack. Due to these persistent weak layers, dangerous avalanche conditions exist above 7,500 feet, and backcountry travelers could trigger small to very large slab avalanches on steep avalanche terrain. Below 7,500 feet, avalanches will be smaller and limited to isolated steep terrain features. Caution is advised for these dangerous conditions, and slab avalanches could occur even after a slope has been tracked when a particularly thin, weak spot on a slope is impacted. For safe backcountry travel, be thoughtful about terrain selection and take the time to evaluate the snowpack in order to determine the presence and characteristics of weak layers.
Skiers and riders have the potential to trigger slab avalanches involving faceted snow and surface hoar. Above 7500 feet, depending on the layer initiated, they could be soft or hard and have depths of two to five feet. At low elevations, where the snowpack is comprised mostly of sugary snow, slab depths of one to two feet are possible in isolated areas.
( Discussion is generated from the previous day's afternoon forecast. )As the main flow of the jet stream passes to the north in Canada, weak weather disturbances will cross the current ridge of high pressure over the region and bring light snowfall to western Wyoming by morning. Accumulation is expected to be 2 to 5 inches by Friday morning and ridgetop winds will be southwesterly to westerly at 10 to 20 miles per hour. The avalanche hazard is expected to be Moderate in the Teton and Togwotee Pass forecast areas. In the Tetons, where the snowpack has reached depths of six feet, weak layers have begun to round and will be difficult to trigger. If one of these avalanches were triggered, slab depths could be up to 5 feet and likely fatal. In the Togwotee Pass area, where the snowpack is still shallow, avalanches will be more easily triggered but smaller with depths up to four feet. Even small avalanches could have severe consequences.In the Southwest Trails/Grey’s River forecast area, the avalanche hazard is expected to be Considerable, where skiers and riders could trigger dangerous avalanches in avalanche-prone terrain with slab depths as large as four to five feet.
