In addition to newly formed shallow wind slabs, the potential still exists for backcountry skiers and riders to trigger deep hard slab avalanches involving weak faceted snow near the base of the snowpack. These deep slabs will be larger, more sensitive, and more widely distributed at the high elevations where conditions remain dangerous and cautious terrain choices are recommended. If considering steeper terrain, careful snowpack evaluation is essential. At the mid elevations, although less likely, large avalanches could still be triggered in areas where the weak layer is present if a particularly thin spot on a slope is impacted. At the low elevations, avalanches are not expected except for small slabs in isolated areas where strong winds this morning have loaded steep starting zones.
At the higher elevations, shallow wind slabs could be triggered to depths to eight inches in steep leeward terrain that was loaded by very strong southwest winds this morning.
Persistent weak layers of faceted snow that formed during the extended dry periods in November and at the end of December continue to be a real threat to backcountry travelers. Many avalanches involving these layers have occurred recently. Above 7500 feet these slabs could have depths of four to seven feet. At low elevations, isolated pockets of slab could be triggered with depths of one to two feet.
Pacific moisture moving up and over a ridge to the west will bring mostly cloudy to overcast skies along with light snowfall to the region tonight and on Thursday. Overnight temperatures in the mountains will remain in the low teens before climbing into the mid-20s during the day. Westerly ridgetop winds will range from 15 to 25 miles per hour.The general avalanche hazard is expected to be Moderate above 7,500 feet on Thursday. Skiers and riders could trigger small pockets of wind slab in steep, wind loaded terrain at the higher elevations. Persistent deep slab avalanches will remain the primary concern. Don’t let a drop in the hazard rating give you a false sense of security. While these slabs continue to be more difficult to trigger, they still carry high consequences. These slabs could be up to 7 feet deep in the Teton and Southwest Trails forecast zones and up to 5 feet in depth on Togwotee Pass. Remember, previous tracks are not an indication of stability with a persistent deep slab problem; your tracks could be the first ones to hit a shallow weak zone, and a deadly avalanche could be the result. Mostly stable snow exists below 7,500 feet.
