A persistent weak layer continues to be a huge concern. Most recreational avalanche fatalities involve the human triggering of a persistent slab avalanche. Most of these accidents occur during periods of moderate or considerable hazard. Managing this hazard requires patience, excellent terrain evaluation skills and conservative terrain choices. In these conditions existing tracks on a slope should not be taken to be an indication of stability.
At the mid and upper elevations slab avalanches 2 to 4 feet in depth can be triggered by humans who venture onto steep avalanche prone slopes. At the lower elevations avalanches are unlikely except on isolated terrain features.
An approaching trough is expected to bring light snowfall late tonight into Saturday morning with an accumulation of only a few inches. Southwesterly winds will increase into the twenties gusting in the thirties and forties. Mountain temperatures will be in the low to mid-teens. Dangerous persistent slab avalanches remain the primary hazard across the forecast area. These avalanches have the potential to be very large with slab depths to four feet and could be triggered by the weight of a single person. As slopes are loaded by the new snowfall and wind transport, depending on the duration and intensity, slabs could become more sensitive to triggers. Although persistent slab avalanches are the main concern, increasing winds will transport loose snow and could form wind slabs along ridges and other terrain features. The avalanche hazard above 7,500 feet is expected to be Considerable in the Grey’s River forecast area and Moderate in the Teton and Togwotee Pass forecast areas. Backcountry travelers should monitor changes in conditions and use careful terrain selection.
