Strong winds and new snow have created new surface slabs and at the upper elevations (above 9,000 feet) increased the load on a persistent weak layer that formed on top of a hard October rain crust. Natural avalanches are possible at the higher elevations. Human triggered slab avalanches are likely in areas where surface slabs lie upon a well-developed weak layer and possible in steep terrain on a variety of aspects above an elevation of 7,500 feet.
At the upper elevations strong west to southwest winds have loaded weak persistent layers of faceted snow that lie upon a hard crust. Dangerous slab avalanches with depths to three feet have potential to release naturally of be easily triggered by the weight of a person in steep wind loaded avalanches paths that face north.
New winds slabs formed by northwest to southwest winds with depths of one to two feet could be human triggered on a variety of aspects at the mid and upper elevations. These slabs could fail on buried density differences, areas of buried sun crust, buried layers of surface hoar and buried layers of faceted snow.
( Discussion is generated from the previous day's afternoon forecast. )A strong jet is steering a plume of Pacific moisture into western and northern Wyoming. A cold front is moving in from the northwest and is forecast to pass through our area around midnight. Present snowfall rates are around two inches per hour. These high snowfall intensity rates are expected to continue until the cold front passes. The snowfall will continue at decreasing rates into the morning hours before tapering to snow showers during the day. Additional accumulations of 8 to 15 inches are expected during the next 24 hours. This set up will favor the Teton Range. Temperatures will drop into the single digits after the passage of the cold front and are expected to fall well below zero on Monday night as cold air moves in behind the departing storm system. Winds will veer to the northwest and continue at speeds of 25 to 30 with gusts to 50 miles per hour until the morning and then decrease to 20 with gust to 30 for the remainder of the day. The avalanche hazard is expected to peak around the time of the passage of the cold front around midnight and then slowly decrease on Monday as the snowfall intensity drops off, cold air moves into the region and winds very slowly decrease. The general avalanche hazard on Monday is expected to be CONSIDERABLE at the upper elevations and MODERATE at the mid and lower elevations. Persistent deep slabs with depths to five feet and wind slabs with depths from one to three feet could be human triggered or release naturally in steep avalanche prone slopes at the upper elevations. Winds slabs with depths up to three feet deep could be human triggered in steep avalanche terrain at the mid and lower elevations.
