Persistent slabs continue to pose a serious threat. Recent new snow and northwesterly winds are increasing the load and the sensitivity of these dangerous hard slabs to human triggers. Conservation terrain choices are warranted. Avalanches are unlikely below an elevation of 7,500 feet.
Hard slabs, with depths to four feet, lie upon persistent weak layers of faceted snow on a variety of aspects. A snowmobiler or the weight of a single skier could trigger one of these hard slabs, especially in areas where the slab is thin. Previous tracks and the lack of recent avalanche activity are not indications of stability.
( Discussion is generated from the previous day's afternoon forecast. )Thermal inversions are expected to develop overnight and trap areas of fog in the valley until around noon. Skies will be mostly sunny in the mountains. Temperatures will drop into the single digits in the mountains and into the single digits below zero in the valleys. Daytime highs will rise into the 20s. Winds will be west to northwest at 10 to 20 miles per hour.Isolated pockets of wind slab less than a foot in depth could be triggered in cliff areas at the highest elevations. The primary hazard at the mid and upper elevations is hard slabs that lie upon persistent weak layers of faceted snow. In general these slab are more likely to be triggered in areas where the total snow depth is less than 50 inches deep and a little less little likely to be triggered but more consequential in areas with a deeper snow cover. These slabs could be 30 to 60 inches deep. The unstable areas are isolated but can be found on all aspects above 7,500 feet. We think these dangerous slabs could still be triggered by the weight of a single person but are more likely to be triggered by snowmobiles. The general avalanche hazard is expected to be MODERATE at the mid and upper elevations and LOW below an elevation of 7,500 feet where avalanches are unlikely.
