Two avalanche problems confront backcountry users today. First, small wind slabs could be triggered in steep, wind loaded terrain above 9,000 feet. Second, persistent deep slab avalanches remain a concern on a variety of aspects above 7,500 feet. These large to very large slab avalanches could be triggered directly by skiers and riders or indirectly from the release of a smaller wind slab. As the day progresses, continued snowfall and strong winds will increase the likelihood, depth and volume of both the wind slabs and persistent deep slabs. Loose snow sluffs will also be possible in very steep, upper elevation terrain that is not significantly wind affected. Monitor weather conditions, and utilize a conservative approach to terrain management. Avalanches below 7,500 feet are not expected today except for on small, isolated features.
Ridgetop winds picked up overnight and are expected to remain strong during the day. With ample snow available for transport along with steady snowfall throughout the day, wind slabs will continue to build. Skiers and riders could trigger these 6 to 18 inch slabs in steep, leeward terrain above 9,000 feet.
The possibility continues for backcountry travelers to trigger persistent deep slab avalanches failing on faceted snow that developed during the December drought period. Large triggers, such as snowmobiles, are more likely to be able to impact this deeply buried weak layer. However, the weight of a single person could cause failure of this weak layer if a shallow trigger point is encountered. These slabs could propagate long distances, have depths to five feet and are likely to carry severe consequences to anyone involved.
( Discussion is generated from the previous day's afternoon forecast. )Light snow showers will linger overnight before steadier snowfall develops on Saturday as an upper level trough moves into the region. Overnight lows in the mountains will be in the upper single digits before rising to near 20 in the afternoon. Southwesterly to westerly ridgetop winds will increase to 20 to 30 miles per hour.The general avalanche hazard is expected to remain MODERATE on Saturday. With increasing winds, new snow and ample snow available for transport, skiers and riders could trigger newly and recently developed wind slabs in steep, leeward terrain in the Tetons. These slabs could fail on density breaks within the recent snowfall, on sun crusts or down to the layer of surface hoar buried on January 19th. Persistent deep slabs with depths up to five feet continue to pose a threat to backcountry travelers in all forecast zones. Large triggers, such as snowmobiles, are more likely to be able to impact the deeply buried weak layer. However, the weight of a single person could cause failure of this weak layer if a shallow trigger point is encountered. These dangerous slabs could also step down from the release of a smaller wind slab. As new snow continues through the day, the hazard will slowly increase. Monitor weather conditions, and avoid steep, wind loaded slopes.
