Yesterday at the Grand Targhee Resort the ski patrol conducted avalanche hazard reduction efforts in the Peaked Mountain and Marys Nipple areas for the first time this season. They were able to explosively trigger two foot deep slab avalanches on northerly aspects at the upper elevations. These slabs failed on the October melt-freeze crust. There remains some potential at the upper elevations for humans to trigger shallow winds slabs and older persistent slabs. Avalanches are unlikely at the mid and lower elevations.
At the upper elevations pockets of wind slab up to one foot in depth were formed by west-southwest winds. These shallow surface slabs could be human triggered in steep upper elevation avalanche starting zones and have the potential on north facing aspects to step down to a depth of two feet to the October crust.
Some potential remains for humans to trigger older slabs up to two feet in depth on steep northerly aspects at the upper elevations. These slabs lie upon a persistent weak layer of buried surface hoar atop on a hard melt-freeze crust.
A new weather system will begin approaching the area late in the day on Saturday and bring an increasing chance of snowfall through Sunday evening. This system will favor the Yellowstone Plateau and the northern portion of the Teton Range. Expect increasing clouds on Saturday with light snow developing in the afternoon and increasing in intensity overnight. Temperatures will be the 20s and 30s. Westerly winds will increase as the day progresses.At the upper elevations areas of instability persist and the general avalanche hazard is expected to be MODERATE. Some potential remains for humans to trigger dense slab avalanches up to two feet in depth, especially on northerly aspects and in cliff areas. Avalanches are unlikely below an elevation of 8,500 feet where the general avalanche hazard is expected to be LOW.
