Tetons

At mid and upper elevations deep new snow ending Monday has added strain to the deep, hard slab instabilities that plague the region. These poorly supported slabs that exist at all elevations, including steep pockets on lower slopes, could fail to the ground and may be triggered by surface slides, a single person, and more likely a snowmobile even after a slope has been crossed multiple times. Monday a skier was caught in a slide in Milelong Couloir, north of the Jackson Hole Resort in Grand Teton National Park. He spent some time under the debris flow but ended up on top, only losing his skis. During and in the days after each snow cycle this season there have been several close calls, burials with injuries or even deaths.

Snow is to fall across the mountains and valleys overnight and through the day on Thursday. Snowfall amounts of six inches to a foot of new snow are possible during this time. Temperatures are to rise into the low twenties and winds are to be southwesterly at 15 to 20 mph. The general avalanche hazard is expected to be Moderate in the Togwotee Pass and Teton forecast areas and Considerable in the Southwest Trails/Greys River area. Backcountry riders and skiers have the potential to trigger hard slab avalanches to the base of the snowpack in steep avalanche terrain. These slabs may fail when a weak spot or trigger point is hit even after a slope has been crossed several times. Larger loads such as snowmobiles or groups of skiers have a greater potential to trigger these weaknesses. Loose snow sluffs and soft surface slabs will become sensitive as new snow accumulates during the day.