New snow overnight and strong winds have created dangerous avalanche conditions at the mid and upper elevations and increased the hazard at the lower elevations. Slab avalanches can be human triggered on a variety of aspects . At the mid and upper elevations very large deep persistent slab avalanches can also be triggered by humans or the release of a wind slab avalanche. A careful assessment of the snowpack and conservative terrain choices are essential for safe travel in avalanche terrain.
Strong westerly winds continue to drift snow onto leeward aspects. At the mid and upper elevations slab avalanches up to three feet in depth could be triggered by humans on steep avalanche prone slopes. At the lower elevations pockets of wind slab one to two feet in depth could be triggered on steep terrain features where drifting has occurred.
At the mid and upper elevations strong winds and recent new snow continue to increase the load on persistent weak layers of faceted snow near the base of the snowpack. Dangerous hard slab avalanches up to five feet in depth could be triggered by a person on this problem layer. These deep slab avalanches are more likely to fail on northwesterly through northeasterly aspects above 8,000 feet and could step down from the release of a wind slab. Being caught in one of these slides could easily result in a fatality.
Northwest flow will continue to bring snow overnight and into Tuesday morning. Snowfall is to diminish on Tuesday as temporary ridging builds. Six or more inches could fall in the Tetons overnight with one to three more during the day. In the valleys, one to three inches is expected. Although less snow is predicted in the southern zone, localized areas could see similar amounts. Winds are to be strongest overnight, however averages are still to remain above twenty miles per hour throughout the day. Wind directions could vary from southerly to westerly. Temperatures at higher elevations are to range from the teens to the lows twenties.The general avalanche hazard will be Considerable in all forecast areas tomorrow. Strong winds and new snow will further load leeward slopes where avalanches could be human triggered with depths of six inches to three feet. The increased load will also add stresses to the deep persistent slab problem. Failure involving this layer is most likely to occur if a slope is impacted by a moving wind slab. If triggered, such an avalanche would be large and could carry dire consequences.
