Backcountry travelers are encouraged to make conservative decisions and to be content with cautious route selection as DANGEROUS avalanche conditions continue. Yesterday, five or six skier triggered slides were reported to the avalanche center and more may have occurred. No one was caught in these events, two of which hit traverses or skin tracks. The slides ranged in hardness from soft to hard and in sensitivity from very touchy remote triggers to stubborn slabs that required "aggressive stomping", indicating their difficulty to predict. New wind slabs are forming at the high elevations on yesterdays snow surfaces. At all elevations, persistent weak snow layers lie at the interface between a dry period and when snow started to fall a week ago as well as deeper in the snowpack. These instabilities could be triggered at all elevations today and have the potential to be large at the mid and upper elevations.
New snow and west winds are forming wind slabs on leeward slopes at the high elevations and the upper portion of the mid elevations. These slabs will be shallow this morning and grow in size and sensitivity as snow accumulates today to depths of a foot.
The presence of a single skier or rider has the potential to trigger slab avalanches in steep avalanche terrain and remote triggering remains a possibility. At the mid and upper elevations slabs could run on sun crusts and surface hoar on southerly aspects and on faceted snow on northerly aspects to depths of of one to four feet. At lower elevations slabs to eighteen inches could be triggered. These slabs could be soft or hard and once initiated, could entrain deeper snowpack layers. Additional snowfall will increase the load on these weaknesses, therefore increasing their sensitivity today.
Areas of moderate snowfall will continue this evening before gradually decreasing. Another 6 to 9 inches are possible at the higher elevations of the Teton Range. Other areas and the lower elevations can be expected to receive another 2 to 6 inches. Light snow showers will linger into Thursday with minor accumulations. Temperatures in the mountains will remain in the upper single digits and teens. Winds will veer to the northwest and decrease overnight and are forecast to back towards the southwest and increase in the afternoon.Conditions remain dangerous. In the Teton Range new soft slabs and large loose snow sloughs are likely to be easily triggered by skier and riders and may release naturally. These new slabs could be up to three feet deep at the mid and upper elevations of the Tetons. In other areas and in the lower elevations of the Tetons pockets of new soft slab 6 to 18 inches in depth could be triggered by humans in steep wind loaded avalanche starting zones. In all areas older persistent slab avalanches could be triggered by humans or be triggered by the release of a surface slab. These dangerous slabs lie upon buried persistent weak layers and could be 2 to 4 feet deep in the Greys River and Togwotee Pass areas and 3 to 5 feet deep in the higher elevations of the Teton Range. The general avalanche hazard is expected to be considerable above an elevation of 7,500 feet in all of our forecast zones tomorrow and moderate below that elevation. Expert terrain elevation and snowpack evaluation skills and a conservative approach are essential for safe travel in avalanche terrain.
