Sunshine and warming temperatures will combine to soften snow surfaces and increase the avalanche hazard. As the day progresses the potential for humans to trigger pockets of wind slab will increase in very steep terrain. Shallow point slides are also possible on very steep sunlit slopes and in areas with long sustained pitches of very steep terrain like the central peaks of the Teton Range these shallow sluffs can run long distances and entrain significant volumes of snow.
Pockets of wind slab up to 18 inches in depth exist at the mid and upper elevations. These slabs and shallow loose snow sluffs will become increasingly sensitive to human triggers as the day progresses and temperatures warm.
A fast moving storm system is approaching from the Pacific Northwest. Clouds will quickly thicken and lower after midnight. Snow is likely to develop during the predawn hours. Snowfall will be heavy at times through the morning and afternoon hours with accumulations of 8 to 12 inches possible by evening. High winds from the southwest will accompany this snowfall. Winds speeds are forecast to average 30 to 45 with gusts from 60 to 70 miles per hour along the higher ridges and in exposed areas. Whiteout conditions will occur in the mountains. Several inches of accumulation are likely at the lower elevations by evening. Temperatures will be in the 20s.Snowfall rates of an inch an hour for a sustained period and high winds will create dangerous avalanche conditions at the mid and upper elevations. New wind slabs will quickly form on slick old snow surfaces. These slabs are expected to build to depths of two feet and quickly become unstable as rapid loading occurs throughout the day. Human triggered avalanches are likely on steep slopes and small and medium sized natural avalanche activity is possible in steep avalanche prone terrain. Conservative terrain choices and a cautious approach will be essential for safe travel in avalanche terrain. Expect the hazard to be rapidly increasing if this weather forecast verifies. The general avalanche hazard above 7,500 feet is expected to increase to MODERATE during the morning hours and increase to CONSIDERABLE as the day progresses. At the lower elevations the existing snowpack is mostly shallow or non-existent and the general avalanche hazard is therefore expected to be LOW.
