Strong winds and new snow have created dangerous avalanche conditions. Yesterday a skier in Grand Teton National Park remotely triggered a large slab avalanche that ran 2,000 vertical feet to the valley floor. In the evening the Wyoming Department of Transportation used a gas exploder to trigger an avalanche in the Twin Slides avalanche path on Mt. Glory that ran across the highway. Winds have formed dangerous slabs on a snowpack that has poor structure and buried weak layers of faceted snow. Human triggered avalanches are likely today on steep wind loaded terrain features. These slab avalanches could be some of the largest of the season and may have severe consequences. Conservative terrain choices are essential for safe travel in avalanche terrain.
At the mid and upper elevations large slab avalanches are likely to be triggered by skiers or riders on steep avalanche prone slopes. These slabs could step down to buried weak layers of faceted snow and could be 1 to 4 feet deep. At the lower elevations pockets of wind slab lie upon depth hoar and could be human triggered with depths to 2 feet.
Temperatures are expected to drop quickly tonight as skies clear and winds diminish. Valleys will be the coldest in the morning as a temperature inversion begins to develop. A sunny day on Tuesday will bring the valley temperatures from potentially near minus twenty degrees up to the single digits. Mountain temperatures should start a little warmer and also rise into the single digits. Winds are to be light and variable. The general avalanche danger is expected to be Moderate tomorrow. The possibility of triggering the new surface slabs and larger, dangerous persistent slabs continues. This lowering of the danger rating is simply due to the slabs becoming slightly less sensitive and naturally occurring events not being expected. It is a time to exercise a lot of caution and not let sunny skies or other factors lure you into steep avalanche terrain as the presence of a single person could still trigger events with dire consequences.
