Dangerous avalanche conditions exist. Up to 40 inches of new snow has fallen in less than three days. Yesterday a skier triggered a large soft slab avalanche in Granite Canyon that climbed the couloir walls and produced a powder cloud that was described as being twice the height of mature trees. Larger avalanche events are likely today and could seriously injure or kill humans who get caught. For this reason a special avalanche bulletin has been issued by the Bridger-Teton National Forest Avalanche Center via the National Weather Service for the Teton Range. Large to very large avalanches are likely to be human triggered in steep avalanche prone terrain at the mid and upper elevations. Natural avalanches are possible, especially if periods of sunshine and a significant increase in forecast winds occur. In very steep terrain not affected by wind, loose snow sluffs could entrain large volumes of new snow and pose a significant hazard. Expert terrain analysis, restraint and conservative decisions with respect to terrain selection are essential for safe travel in the backcountry today. At the lower elevations it is prudent to avoid the run out zones of overhanging avalanche paths.
At the mid and upper elevations soft surface slabs one to four feet in depth could be triggered by humans in steep avalanche prone terrain. These slabs could fail on crusts and firm old snow surfaces or on density changes within the storm snow. These deep wind slabs have been formed by southwest to northwest winds. Natural releases are possible.
Loose snow sluffs could be human triggered or release naturally in steep terrain. These sluffs could entrain significant volumes of new snow and become dangerous.
Orographic snow showers are to continue through Thursday. Snowfall amounts are hard to predict but should be in the two to five inch range. Temperatures are to rise into the low twenties. West winds will become northwesterly with ten to fifteen mile per hour averages. The general avalanche hazard will remain Moderate in the Togwotee Pass area where deep instabilities persist and a slight chance continues for hard slabs in high avalanche terrain. In the Teton and Southwest trails areas the hazard will be Considerable. New wind slabs with depths to 3 feet could be triggered at higher elevations in very steep terrain. The depths and sensitivity of these slabs lessens at lower elevations.
