Dense mountain snowfall, sporadic valley rain, warm temperatures and strong westerly ridgetop winds have conspired to create dangerous avalanche conditions. Yesterday, a skier remotely triggered a large avalanche near the Plumber Canyon yurt. This slide, which occurred on an easterly aspect at 8,000 feet, failed on faceted snow at the base of the snowpack. A snowboarder also triggered a shallow wind slab that reportedly stepped down 8 feet outside the southern boundary of the Jackson Hole Mountain Resort. Shallow wind slabs are also likely to be skier triggered, and natural wet slabs are possible at the lower elevations. Any extended periods of sunshine in the afternoon will exacerbate these avalanche problems.
Strong westerly ridgetop winds have created dense wind slabs in exposed terrain at the mid and lower elevations. Skiers and riders could trigger these slabs to depths of one to three feet. These slabs could step down to persistent weak layers deeper within the snowpack.
Above freezing temperatures for the last two nights, combined with the chance of rain, will make natural wet slides possible at the lower elevations on steep slopes. These slides could release to the ground.
Dense snowfall has added load to persistent weak layers formed during drought periods earlier in the season. Warm temperatures have also made these layers more susceptible to failure. At the mid and lower elevations, where faceted snow near the base of the snowpack is more prevalent, skiers and riders could trigger deep persistent slabs to the ground.
Light, scattered snowfall is possible tonight and Wednesday, along with periods of sunshine during the day. Overnight lows in the mountains will be near 20 before rising into the upper 20s during the day. Valleys lows should drop below freezing before rising to near 40 during the day. Westerly ridgetop winds will range from 20 to 30 miles per hour.The general avalanche hazard is expected to remain CONSIDERABLE on Wednesday. Backcountry travelers could trigger dense wind slabs with depths of one to three feet in steep, wind-loaded avalanche starting zones. Large, dangerous hard slabs up to eight feet in depth could also be triggered by skiers and riders in areas where weak layers of faceted snow persist within the snowpack. At the lower elevations, warm temperatures and latent heat in the snowpack will keep wet slides possible.
