Strong winds and increasing temperatures are causing slab development on the snow surface and changing the characteristics of the snowpack. Rapidly increasing snowfall rates will combine with these elements to increase the avalanche hazard and create dangerous conditions. On west through north to east aspects above an elevation of 9,000 feet rapid loading of avalanche starting zones will increase the load on a persistent weak layer. The likelihood for large and destructive human and naturally triggered avalanches will increase as the day progresses and is expected to rise to high at those upper elevations during the afternoon or evening hours. Travel in avalanche terrain is not recommended when the hazard is high. Concurrently these conditions will be creating surface slabs at the mid and upper elevations that could be human triggered in steep wind loaded avalanche prone terrain. Due to low snow depths avalanches are unlikely at the lower elevations except in isolated terrain features.
Strong west and southwest winds and increasing snowfall rates will rapidly load avalanche starting zones. Human and naturally released slab avalanches with depths to four feet are likely. Although these slabs could be triggered by the weight of a single person and release naturally multiple tracks on a suspect slope should not be considered to be an indication of stability.
New winds slabs formed by west and southwest winds will gain depth and volume as the day progresses. These slabs could be human triggered with depths that will increase to two feet later in the day. These slabs could fail on buried density differences, areas of buried sun crust, buried layers of surface hoar and buried layers of faceted snow.
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.
