At the higher elevations, backcountry skiers and riders could trigger surface slabs in steep, wind-loaded avalanche starting zones and cliff areas. These slides are most likely to be triggered near upper elevation ridge lines and beneath cornices where winds continue to drift available snow onto leeward slopes. Very large persistent deep slabs are still a potential threat in terrain above 9,000 feet, especially for larger triggers like snow machines.
At the upper elevations and in isolated areas at the mid elevations, pockets of surface slab formed by west to southwest winds could be human triggered with depths to two feet in steep wind loaded avalanche starting zones and cliff areas.
Persistent deep slabs remain a concern in steep avalanche prone terrain above an elevation of 9,000 feet that face east through north to west. The release of one of these dangerous slab avalanches is more likely with large triggers, such as snowmobiles or cornice drops. Previous tracks are not an indication of stability. These destructive slides could exceed six feet in depth.
Moderate to heavy snowfall is expected late tonight through Wednesday night in the Salt River Range, Wyoming Range and over the mountainous areas of southeast Idaho. Lesser amounts are forecast for the Teton and Togwotee Pass areas. Total snowfall accumulations by Thursday morning are expected to be 10 to 16 inches in the Greys River area and 5 to 10 inches in the Teton and Togwotee Pass areas. Temperatures will remain in the single digits above and below zero. Southwest winds will veer to the northeast during the day and be light with average speeds of 10 to 20 miles per hour. The general avalanche hazard is expected to be MODERATE and increasing, especially in the Greys River forecast area where it could increase to CONSIDERABLE. Soft surface slabs up to two feet in depth and loose snow sluffs could be human triggered in steep terrain. Deep persistent slabs with depths to six feet could be human triggered in steep north facing avalanche prone terrain above an elevation of 9,000 feet. These dangerous deep slabs are more susceptible to heavy triggers like snow machines.
