There were three close calls in Grand Teton National Park yesterday. In one incident a skier who triggered a shallow wind slab in the Turkey Shoot on Peak 25 Short was carried a long distance but not injured. In another incident in a very steep chute on a northeast aspect of Peak 25 Short a skier triggered a shallow slab avalanche that ran the full length of that chute. In a third incident a skier was caught and partially buried on a north facing slope near the top of Maverick. Similar events are possible today. In very steep chutes small slab avalanches can very quickly become dangerous. At the higher elevations recent new snow and westerly winds have formed wind slabs that can be human triggered on steep slopes. Recent new snow is increasing the load on deeply buried persistent weak layers. At the lower elevations overnight temperatures were near freezing. Watch for unstable conditions on very steep terrain features and be aware of the potential for roofs to slide.
At the mid and upper elevations wind slabs formed by west-northwest to southwest winds could be triggered on steep terrain features. These slabs could be 1 to 2 feet deep and could become a significant hazard in very steep chutes, cliff areas and above terrain traps.
Some potential continues for humans to trigger deep persistent slab avalanches. Although the likelihood for these large slab avalanches to be human triggered is low the consequences of triggering a slab avalanche 3 to 7 feet deep are likely to be fatal. These dangerous slabs could be triggered when a person crosses a thin area of a deep persistent slab, by larger triggers like snowmachines or by the release of a surface slab.
Periods of light snow could hit higher terrain overnight before flow backs to the southwest and moisture increases Tuesday morning. Snow should develop by noon, increase in the afternoon, and continue through the night. Mountain temperatures are to rise from the low teens to the mid-twenties. Winds will become southwesterly and have 15-20 mph averages. The general avalanche hazard will be Moderate above 7500 feet. Although the wind slabs are gaining some strength, they can still be triggered by a single person in steep terrain with depths to two feet. The chance also continues for triggered wind slabs or a large trigger to initiate failure of large to very large deep slab avalanches. Avalanches at low elevations are unlikely except for in small isolated pockets in the steepest terrain.
