Yesterday a skier was caught and carried but not injured in a large slab avalanche in the Teton Range. This event occurred on a lower angle slope that was not expected to be unstable. The slide stepped down to a weak layer that formed in December. Similar events are likely today in the Southwest Trails area. Up to an inche of moisture has been loaded onto the snowpack in the past 24 hours. Dangerous deep slab avalanches are likely and could be triggered by the weight of a person or by the release of a surface slab. Wet slides could be a potential hazard on isolated terrain features below an elevation of 7,500 feet.
Dangerous deep slab avalanches up to four feet in depth could be human triggered or release naturally on a variety on aspects above an elevation of 7,500 feet. These slabs could fail due to the weight of a snowmobile or a single skier who encounters a shallow weak zone. These slabs could propagate and run long distances and are likely to carry severe consequences to anyone involved.
Strong westerly winds have loaded leeward slopes. Dense wind slabs up to two feet in depth could be human triggered and once triggered could step down and become a dangerous deep slab avalanche.
( Discussion is generated from the previous day's afternoon forecast. )A pulse of moisture in the strong northwest flow will bring periods of moderate to heavy snowfall overnight. Accumulations of 5 to 10 inches are possible by morning. Lighter snowfall during the day could bring another 2 to 5 inches to the mountains on Monday. Strong westerly winds will create areas of blowing and drifting snow. Cooler air will begin to move into the region. Temperatures will be in the 20s in the mountains and in the low to mid 30s in the valleys. The new snow and strong, gusty winds will be increasing the general avalanche hazard in the mountains and be creating dangerous avalanche conditions. Large to very large deep slab avalanches could be human triggered or release naturally with depths to 5 feet on a variety of aspects at the mid and upper elevations. Winds slabs 1 to 3 feet in depth could also be triggered by humans at the higher elevations in steep wind loaded avalanche starting zones, cliff areas and in steep couloirs and could step down to the December layer. The general avalanches hazard is expected to be CONSIDERABLE except at the lower elevations (below 7,500 feet) where avalanches are unlikely and the hazard is expected to be LOW. Excellent terrain analysis skills and conservative terrain choices are warranted. AVALANCHE ACCIDENTS INVOLVING BACKCOUNTRY USERS ARE LIKELY.
