Dangerous avalanche conditions exist at the mid and upper elevations. There, two avalanche problems confront backcountry users today. First, small to large wind slabs could be triggered by backcountry travels or release naturally. Second, very large deep persistent slabs could also be human triggered or release naturally. The deep persistent slabs are confined to terrain that held snow from early October, but pose a much greater threat with slab depths that could exceed six feet. Conservative decision making and expert route finding will be essential for safe travel in avalanche terrain. At the lower elevations, cold temperatures have decreased the avalanche hazard, and the snowpack is mostly stable.
Wind slabs up to three feet deep were formed by recent snowfall and very strong southwesterly to westerly ridgetop winds. On a variety of aspects above 7,500 feet, these slabs could be triggered by backcountry travels or release naturally.
Deep hard slabs rest upon weak, faceted snow and crusts near the base of the snowpack. At the upper elevations, these instabilities exist on westerly through northerly to easterly aspects and dip into mid elevation terrain on north facing slopes. Natural activity on this persistent weak layer occurred as recently as Friday. With slab depths in excess of six feet, surviving one of these slides is unlikely.
Skies will become mostly clear after midnight and inverted temperatures will develop. Overnight lows in the mountains will be in the negative teens as the valley plummets into the negative mid 20s. Periods of cloud cover and sunshine are expected during the day, and highs will be near zero at all elevations. Northwesterly ridgetop winds will range from 15 to 25 miles per hour.Dangerous avalanche conditions exist above 7,500 feet, and the general avalanche hazard is expected to remain CONSIDERABLE on Sunday. Two avalanche problems will confront backcountry travelers. On a variety of aspects above 7,500 feet, backcountry travelers could trigger recently developed wind slabs up to three feet deep in steep, wind-loaded avalanche terrain. Deep persistent slabs similar to the events that occurred on Thursday and Friday could also be human triggered with fatalities being a likely outcome. While the chance for natural activity for these two problems is decreasing, it might still be possible. Conservative decision making and expert route finding will be essential for safe travel in avalanche terrain.
