Very dangerous conditions exist at all elevations. The Bridger-Teton National Forest Avalanche Center has issued an avalanche warning. Travel is not recommended in avalanche terrain. Up to 18 inches of new snow with up to 2 inches of moisture has fallen in the mountains since early yesterday morning. Natural avalanche activity is likely and may become widespread. Large avalanches could run long distances. Avalanches could affect roadways. Avalanches are possible on buttes, steep banks, road cuts and steep hillsides that don't normally slide. Stay off of and out from under steep slopes. Dangerous roof slides are likely.
At the mid and upper elevations strong southwest winds have formed dense, unstable wind slabs on lighter density snow. At the lower elevations these slabs are forming on top of a snowpack that has poor structure. Natural and human triggered releases are very likely. These destructive slabs could be up to three feet deep at the upper elevations and up to two feet deep at the lower elevations.
Large to very large slab avalanches could fail on persistent weak layers on a variety of aspects at all elevations. At the lower elevations these slides are very likely, could be wet and may dig down to the ground with total slab depths to four feet. At the higher elevations these destructive slabs could be up to six feet deep and run long distances.
A cold front is expected to pass through the area tonight and bring moderate to heavy snowfall to the region. Gusty west-southwest winds will accompany the frontal passage. Those winds are forecast to increase to 35 with gusts to 50 miles per hour by daybreak. Temperatures will remain warm until after midnight and are expected to be in the teens in the morning and rise in the upper 20s during the day. The avalanche warning issued by the Bridger-Teton national Forest Avalanche Center will expire at 9 PM tonight. Conditions will still be dangerous in the backcountry. Large slab avalanches are possible on steep avalanche prone slopes. These slabs are likely to be triggered by humans in steep avalanche starting zones. Natural releases are possible. Avalanches involving the new snow could be 1 to 3 feet deep. Avalanches that step down to persistent weak layers could be 2 to 5 feet deep. The general avalanche hazard is expected to be considerable. Expert snow stability and terrain evaluation skills are essential for safe travel in avalanche terrain.
