Since late Thursday night, there have been 8 inches of new snow and sustained westerly to southwesterly winds. These conditions have formed new wind slabs on leeward slopes, but more importantly, have increased the load upon a weak snowpack creating dangerous avalanche conditions. Avalanches are likely today, and a single person could easily trigger a large to very large avalanche that would have unsurvivable consequences. These slides could run long distances, so backcountry travelers should avoid being on or below avalanche-prone terrain. The avalanche hazard will be Considerable above 7,500 feet and Moderate below that elevation, where slab depths will be smaller and isolated to steep avalanche terrain. Cautious route finding will be essential to safely travel through the mountains today.
Deep slab avalanches are a serious threat on a variety of aspects. These destructive avalanches could be 4 to 8 feet deep and run long distances above an elevation of 7,500 feet and could be 2 to 4 feet deep below that elevation. If you trigger one of these destructive slides, you will most likely not survive. Previous tracks on a slope should NOT be interpreted as a sign of stability.
Southwest to west winds has formed new wind slabs on leeward aspects. These surface slabs could be 1 to 3 feet deep and be easily triggered by the weight of a person. These wind slab avalanches could step down and trigger a much larger deep persistent slab avalanche.
( Discussion is generated from the previous day's afternoon forecast. )Snowfall is expected to continue overnight with an additional 4 to 8 inches across the forecast area by morning. The heavier snowfall amounts should continue to favor the Grey’s River and Teton forecast areas. Southwesterly to westerly ridgetop winds will be 15 to 30 mph and then lessen by tomorrow afternoon. A weak northwest flow will bring mostly cloudy skies and light snowfall through tomorrow, and then dry weather is expected as a ridge builds over the region. Temperatures will be cold starting in the single digits and then warming into the low to mid-teens. Snowfall and wind continue to load the snowpack and form wind slabs on leeward slopes. Humans are likely to trigger slab avalanches up to 8 feet deep. Winds slabs at the upper elevations are expected to be sensitive and up to 3 feet deep. Triggering a smaller wind slab could step down and initiate a larger avalanche with un-survivable consequences. Depending on the intensity and duration of the storm overnight will determine the likelihood of triggering an avalanche tomorrow. At the highest elevations, the avalanche hazard is expected to be High and Considerable in areas with less snowfall and wind effect. Regardless, conditions are dangerous and travel in avalanche terrain is not recommended.
