At the mid and upper elevations new snow and westerly winds have formed new soft slabs on leeward aspects that were triggered by skiers and snowboarders in steep avalanche terrain yesterday. With more new snow overnight similar but larger events are possible today. At these elevations deep persistent slab avalanches are still a concern. At the lower elevations overnight temperatures were near freezing. Watch for unstable conditions on very steep terrain features and be aware of the potential for roofs to slide.
At the mid and upper elevations shallow soft slabs formed by westerly winds could be triggered in steep wind loaded avalanche starting zones. These slabs could be 6 to 18 inches deep and could become a significant hazard in very steep chutes, cliff areas and above terrain traps.
Some potential continues for humans to trigger deep persistent slab avalanches. Although the likelihood for these large slab avalanches to be human triggered continues to slowly decrease the consequences of triggering a slab avalanche 3 to 7 feet deep are likely to be fatal. These dangerous slab avalanches are most likely to be triggered when a person crosses of a thin spot in the slab or by a larger trigger like a snowmachine.
Snow is expected to continue overnight before beginning to subside around midday on Monday. Accumulations of 3 to 6 inches are likely in the mountains. Greater amounts are possible in the Teton Range. An inch or two can be expected at the lower elevations. Winds will be from the southwest overnight and then veer to the west-northwest after sunrise. Average wind speeds on the peaks are forecast to 10 to 20 with gusts to 30 miles per hour. In the mountains temperatures will be in the teens and 20’s. Valley temperatures will be in the low 30’s by dawn.Recent snowfall is favoring the Teton Range. New soft slabs are gaining size and depth and have been easily triggered by skiers and riders. Some new slab development is likely occurring at the higher elevations in the other forecast areas. The new precipitation is also increasing the load on deeply buried persistent weak layers that have a history of producing very large slab avalanches. At the lowest elevations above-freezing temperatures may create the potential for wet slides to occur on very steep slopes. The general avalanche hazard is expected to be moderate on Monday. Soft slab avalanches up to two feet in depth could be human triggered on steep slopes. Deep persistent slab avalanches are still a concern. These slabs could be triggered when a person crosses a thin area of a deep persistent slab, by larger triggers like snowmachines or by the release of a surface slab. Evaluate the snow and terrain carefully.
