Strong winds and moderate to heavy snowfall will combine to increase the avalanche hazard at all elevations during the afternoon and especially during the evening hours. Southwest winds will create new wind slabs on leeward aspects that will become sensitive to human triggers. At the upper elevations rapid loading will increase the potential for dangerous deep slab avalanches to become unstable. The greatest impacts from an approaching storm system are expected to occur overnight. Blowing snow will create areas of reduced visibility. Monitor conditions for escalating avalanche hazards and be prepared to adjust travel plans if intense loading conditions develop.
At the upper elevations deep hard slabs with depths to six feet continue to be a concern on west through north to east aspects. Areas of blowing snow will rapidly load avalanche starting zones and increase the potential for deep slab avalanche occurrences.
Southwest winds will begin to form new wind slabs on leeward aspects. These new surface slabs will become increasingly sensitive to human triggers as the day progresses. It is possible that human triggered wind slabs up to two feet in depth could be triggered in steep avalanche starting zones on a variety of aspects.
The main brunt of this storm system will impact the region overnight and should continue to favor the Teton Range, Snake River and Salt River Ranges. Another five to eight inches of new snow will accmulate in those ranges by tomorrow morning. Lesser amounts are to be expected in the Wyoming and Gros Ventre Ranges and the Togwotee Pass area. Snowfall is expected to decrease on Wednesday with another one to three inches possible in the mountains. Temperatures will remain in the single digits and teens in the mountains. Winds will veer back to the west overnight and slowly decrease from 35 to 20 miles per hour during the next 24 hours. Wind slabs will continue to grow in size and distribution overnight and into Wednesday. These slabs will build to depths of two feet and are likely to be sensitive to human triggers in steep, wind loaded avalanche starting zones. The added load to our deep persistent slabs at the upper elevations merits a conservative approach to terrain selection. Large dangerous slabs with depths to six feet are possible on shaded aspects above an elevation of 9,000 feet. The general avalanche hazard is expected to be CONSIDERABLE. Human triggered avalanches are likely and large dangerous deep slab avalanches are possible.
