A deep persistent slab problem exists in the Southwest Trails/Greys River area. Weak layers formed during extended dry periods remain susceptible to being triggered by large impacts such as snowmachines or falling cornices. Yesterday a large to very large slide released to the ground on Lava Mountain in the Togwotee Pass area when a chunk of cornice fell onto the slope. Increasing temperatures and direct sunlight will soften the snow surface on sunlit slopes and wet loose avalanches will become possible in steep terrain. Avoid being on or under steep south facing slopes this afternoon. In the valleys, beware of exposure to roof slides.
Deep persistent slab avalanches could be triggered with depths of three to six feet. Previous tracks do not validate stability. Beware of slopes under large cornices.
( Discussion is generated from the previous day's afternoon forecast. )Tuesday will be sunny with calm winds and slightly warmer temperatures. The general avalanche danger in the Tetons will increase from Low in the morning to Moderate in the afternoon as the surface of the snowpack softens and wet loose slides become possible at all elevations on steep sunlit slopes. In the Togwotee Pass Area and in the Southwest trails areas where the chance for deep slab avalanches continues the danger will be Moderate. Large triggers such as a snowmachine hitting a weak point or, as in today, a large cornice impacting a slope may be needed to cause failure. Although the rating will not change, the chance for cornice failure and the chance for wet slides will increase in the afternoon. At low elevations and valleys, roof slides are becoming more likely during this warming trend.
