Six to 12 inches of new snow has fallen since Saturday afternoon. Strong and gusty winds will be forming new soft slabs on leeward aspects. Humans who venture onto steep avalanche prone slopes could trigger these slabs. The new snow and winds have also increased the load on persistent weak layers. This new load is especially significant in areas where the snowpack is shallow and has poor structure. Large persistent slab avalanches could be human triggered with potentially serious consequences. Monitor conditions. Stronger than forecast winds could rapidly increase the avalanche hazard. A careful evaluation of the snowpack and terrain is warranted.
New soft slab avalanches formed by west-southwest winds could be triggered by humans on steep wind loaded slopes. These slabs could be up to 18 inches deep at the mid and upper elevations. Pockets of wind slabs up to a foot in depth could be human triggered in steep terrain features below an elevation of 7,500 feet.
New snow and winds have increased the load on persistent weak layers. Large slab avalanches 2 to 4 feet deep at the mid and upper elevations and 1 to 2 feet deep below an elevation of 7,500 could be triggered by the weight of a single person.
( Discussion is generated from the previous day's afternoon forecast. )A cold front is forecast to move across western Wyoming from eastern Idaho this evening. Snowfall intensity has already increased on the west slope of the Teton Range. Grand Targhee Resort has received five inches of new snow since 5 PM. Snowfall will be heavy at times until midnight. Snowfall after midnight will be light with a lull during the morning hours before increasing again in the afternoon and evening. Forecast snowfall totals during the next 24 hours are 3 to 6 inches in the Togwotee Pass area, 6 to 8 inches in the Southwest Trails area, up to ten inches in the Teton area and two to three inches in the valleys. Temperatures will be in the single digits and teens. South winds will veer to the southwest and west and increase to 25 with gusts to 40 miles per hour. These winds will create areas of blowing snow. The general avalanche hazard will be on the increase in areas that have received the most new snow and experienced the strongest winds. These winds will form new soft slabs on leeward aspects which could build to depths of 1 to 2 feet. The new snow will continue to increase the load on persistent weak layers. Large persistent slab avalanches may become unstable on steep slopes that experience rapid loading during the passage of tonight’s cold front. Depending on the distribution of snowfall tonight and the veracity of the winds the general avalanche hazard is expected to be considerable in some areas of the Teton zone and possibly some areas of the Southwest Trails forecast zone. It is expected to be moderate in the Togwotee Pass area.
