The National Weather Service has issued a Winter Weather Advisory for Western Wyoming effective from 5 AM this morning to 5 AM Tuesday morning. As the day progresses, new surface slabs will build at the upper elevations. These slabs are forming on faceted snow and a hard rain crust that formed in October which persists on easterly through northerly to westerly aspects above 9,000 feet. In these areas, skiers and riders could trigger these shallow slabs, along with loose snow sluffs. Early season conditions exist, and even small slides can cause serious injury by carrying backcountry travelers into exposed rocks and other obstacles. Elsewhere, the snowpack lacks sufficient depth for avalanche activity.
The chance for backcountry travelers to trigger new surface slabs will increase during the day on steep, avalanche-prone slopes where the October crust exists. These slabs could be up to a foot deep by this evening.
Snowfall will begin to taper off overnight, and mostly dry conditions along with decreased cloud cover are expected on Tuesday. Overnight lows in the mountains will dip to near 20 tonight before rising to near 30 during the day. Westerly to northwesterly ridgetop winds will range from 5 to 15 miles per hour.On Tuesday, the general avalanche hazard is expected to be MODERATE in the Tetons above 9,000 feet. The avalanche hazard is primarily limited to mostly shaded terrain where the October crusts exists. There, skiers and riders could trigger surface slabs up to a foot deep on steep, avalanche-prone slopes. In the Togwotee Pass and Greys River areas, the general avalanche hazard is expected to be LOW. While the October crust can be found in terrain above 9,000 feet, it is more limited to northerly aspects. There, backcountry travelers might be able to trigger an isolated pocket of shallow, newly-developed surface slab.In terrain where the October crust is not present, avalanches are unlikely.
