Four skiers have been caught in avalanches during the past two days. Yesterday a skier was caught and partially buried south of Teton Pass and a skier was carried a short distance by a small slide on Togwotee Pass. Two skiers were caught and carried in Grand Teton National Park on Saturday. Similar events are possible today. Recently formed wind slabs lie upon density differences and a well-developed layer of buried surface hoar that formed during a dry period 10 days ago. A deeply buried layer of weak faceted snow that formed in early December continues to have potential to fail due to the weight of a person and produce large, deep slab avalanches. Warming temperatures and periods of sunshine today could increase the sensitivity of these slab avalanches to human triggers. A careful analysis of the snowack and terrain combined with conservative terrain choices are essential for safe travel in avalanche terrain.
Surface slabs formed by southwest to west winds are likely to be triggered by skiers or riders on steep avalanche prone slopes at the upper elevations and could be triggered by humans at the mid elevations. These wind slabs could be up to 30 inches deep. Wind slabs are not likely at the lower elevations.
Dangerous deep slab avalanches continue to be a hazard at the mid and upper elevations. These large slab avalanches are most likely to be released by a snowmachine, however, the weight of a single person could cause failure if a shallow trigger point is encountered. These slabs could propagate long distances, have depths to five feet and are likely to carry severe consequences to anyone involved.
Mostly dry and mild weather will continue overnight and into Tuesday morning. The next storm system will begin to bring some snow to the mountains during the day and will last into Wednesday night. Temperatures will drop into the 20s overnight and rise into the upper 20s and 30s during the day. Southwest to west winds will increase to 20 to 40 with gusts to 45 to 60 miles per hour.At the mid and upper elevations (7,500 to 10,500 feet) dense wind slab avalanches one to three feet in depth could be triggered by skiers and riders who venture onto steep avalanche prone slopes. Deep persistent slabs up to five feet in depth also have potential to be triggered by backcountry riders and skiers. The general avalanche hazard is expected to be MODERATE at the mid and upper elevations. Careful terrain and snowpack analysis is still warranted as most avalanche fatalities occur during periods of moderate or considerable hazard. Avalanches are unlikely below an elevation of 7,500 feet.
