Tetons

Areas of unstable snow exist on steep slopes at the mid and upper elevations. Over the long weekend several close calls occurred on a variety of aspects. Most slides were dense slabs 18 inches to 3 feet deep that ran on a sun crust lubricated by a layer of buried surface hoar on south to northeast aspects although Sunday a skier was partially buried on a north facing slope in Granite Canyon. The slabs will continue to be sensitive to human triggers today on a variety of aspects. Some potential may remain for larger triggers such as snow machines to release deeper hard slabs on weak snow at the base of the snowpack.

The general avalanche hazard in the Tetons and Togwotee Pass areas will be MODERATE Wednesday. Backcountry travelers could trigger slabs 18 inches to three feet in depth on steep slopes. There were a number of close calls and partial burials over the weekend. There have been no deep, hard-slab slides in February in the Tetons and although loose depth hoar persists in some areas like very steep terrain over cliff bands it would likely require the weight of much more snow or several people, or snow machines to break out a slab. 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. The steep, east slope of Lava Mountain slid during or just after the last storm showing that the right conditions of winds over a good wind fetch (the large, flat summit plateau) can move enough snow onto a steep slope to create hazardous conditions.In the Greys River area the hazard is expected to remain CONSIDERABLE. Dense surface slabs to three 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 continue to be possible to trigger avalanches on steep terrain especially by high marking.