Tetons

Areas of unstable snow exist on steep slopes at the mid and upper elevations. Yesterday a skier was partially buried but not injured in Granite Canyon. On Saturday there were numerous close calls, some of which involved large avalanches. A snowmobiler was seriously injured near Togwotee Pass. Dense surface slabs up to three feet in depth lie upon buried surface hoar and slick suncrust. These dense slabs could be triggered by humans on a variety of aspects. Some potential may remain, especially for larger triggers such as snow machines, for humans to trigger full depth hard slabs on weak depth hoar at the base of the snowpack.

The general avalanche hazard in the Tetons and Togwotee Pass areas will be MODERATE Tuesday. Backcountry travelers could trigger slabs 18 inches to 3 feet in depth on steep slopes. There were a number of close calls and partial burials over the long weekend. There have been no deep, hard-slab slides in February in the Tetons and the possibility of releasing them is diminishing.On Saturday a snowmobiler, stuck on a west facing slope near Brooks Lake, was injured in a slide when another rider rode onto the slope to help him. The weight of the two machines, riders and the weakening of the slope by their tracks, all helped trigger the slide. Similar results should be expected even on slopes that otherwise may seem stable.In the Greys River area the hazard is expected to remain CONSIDERABLE. Dense surface slabs to 3 feet in depth could be triggered on a variety of aspects. Large slides were observed Monday just north of the Greys River/Southwest Trails forecast area. A more sensitive snowpack in the region has resulted in a number of close calls. As the new snow settles it will be particularly easy to trigger avalanches on steep terrain by high marking.