Since late Wednesday night, a system has brought fifteen to twenty two inches of snow to the Tetons. This storm was accompanied by strong southwest winds, particularly during its onset Wednesday night into early Thursday morning. Wind slabs lie at all elevations and can be triggered today by skiers or riders particularly in very steep terrain. Deep in the snowpack, the chance continues for avalanches to occur involving weak faceted snow. Between one and two inches of water has fallen on the snowpack, making these older instabilities more susceptible to failure. More snow expected today and Saturday will further load the surface slabs as well as the deep instabilities. Conservative decision making is essential today.
Strong winds this week and continued snowfall, particularly yesterday, have formed soft wind slabs at all elevations. At low elevations they lie upon faceted and could release to 12 inch depths. At higher elevations, they lay upon harder snow surfaces and could have depths to three feet. Watch steep terrain with areas of wind loading.
Above 7500 feet, hard slabs with depths to five feet lie upon persistent weak layers of faceted snow. Although these slabs have become less likely to trigger, the chance remains for them to be initiated by larger loads such as groups or from a wind slab being triggered and causing a secondary failure.
After a lull in the action tonight, another storm is to impact the area by the late morning. Snowfall is to increase through the afternoon and evening. Mountain temperatures are to rise from the single digits to near twenties degrees. Winds are to be westerly with twenty to twenty five mile per hour averages.The general avalanche hazard will be Moderate in morning. The hazard could raise to Considerable in the afternoon depending on the timing and intensity of the next system. New and recent snow and periods of strong winds over the week have formed slabs that could be triggered to depths of two feet in steep wind loaded terrain. Older weaknesses that lie near the base of the snowpack also pose a threat. Although failure of these deeper instabilities is trending toward unlikely, larger triggers such as groups of people or the triggering of one of the surface slabs could still cause a large hard slab avalanche to occur.
