Conditions remain dangerous in the backcountry. Yesterday a snowboarder remotely triggered a 20 inch deep slab avalanche on an east aspect at an elevation of 8,200 feet in Grand Teton National Park. Very large slab avalanches released naturally on Sunday night. Close calls involving skiers occurred on Sunday and Monday. These events are failing on persistent weak layers of faceted snow. Large slab avalanches can still be human triggered on a variety of aspects. Due to the size of the recent avalanches and their distribution throughout our terrain a cautious approach to avalanche terrain is warranted. Avalanches are unlikely below an elevation of 7,500 feet except in isolated areas.
At the mid and upper elevations dangerous persistent deep slabs up to five feet in depth could be human triggered on a variety of aspects. These slabs could fail due to the weight of a snowmobile or a single person who encounters a shallow weak zone. These slabs could propagate and run long distances and are likely to carry severe consequences to anyone involved.
Dense wind slabs formed by strong westerly winds could be human triggered to depths of two feet and once triggered could step down and become a large destructive deep slab avalanche.
Periods of light snow overnight are to be followed by more consistent snowfall on Thursday. Accumulations by evening of 3-6 inches are expected at the higher elevations. Winds are to be westerly with twenty to thirty miles per hour averages, causing periods of blowing and drifting snow. Temperatures are to remain in the low to mid-twenties.The general avalanche hazard is expected to be Moderate. The likelihood of triggering deep slab avalanches on a variety of aspects and wind slabs on certain aspects at high elevations has diminished but still exists. Avalanches below 7500 feet are unlikely however hazard from above should be considered.
