Massive natural avalanches of historic size occurred yesterday in the Greys River/Southwest trails area. In the Hoback River Canyon two massive avalanches impacted the highway. A Class V-sized avalanche impacted the groomed trail to Granite Hot Springs at about 1:30 PM. Two snowmobilers who were swept off of the Greys River Road deployed airbags and survived even though one of their sleds ended up in the river. The colder temperatures, lower wind speeds and dry conditions will combine to lessen the avalanche hazard. However, the snowpack will still be adjusting to the intense loading, rain and warm temperatures, which have occurred during the past ten days. At the mid and upper elevations the potential for large destructive avalanches to release naturally is anticipated to be greatly diminished. The potential for humans to trigger these very dangerous slides will persist. The possibility for wet slides at the lower elevations is also expected to be diminished. Naturally released wet slides are unlikely, but some potential for human triggered wet slides may persist.
Dense wind slabs formed by westerly winds with depths of one to three feet could be human triggered in steep wind loaded avalanche starting zones. These slabs could step down to deeper layers of weak faceted snow in areas with poor snowpack structure.
Buried layers of weak snow persist at all elevations. Slabs that lie upon these weak layers could be triggered by backcountry riders and skiers today. These slabs could have depths of three to five feet.
At the lower elevations some potential may persist for humans or wildlife to trigger large wet slides today on very steep, snow-covered slopes.
( Discussion is generated from the previous day's afternoon forecast. )Snow is forecast to end early this evening. Only a couple inches of new accumulation are expected before skies begin to clear. Temperatures are expected to drop into the lower teens to single digits at all elevations by morning. On Monday skies will be partly cloudy. Temperatures will warm in to the 20s in the mountains and into the low 30s in the valleys. Winds will be westerly overnight and back towards the southwest during the day ahead of the next approaching storm system. Winds speeds along the highest ridge lines are forecast to be 15 to 30 miles per hour.The colder temperatures, lower wind speeds and dry conditions will combine to lessen the avalanche hazard. However the snowpack will still be adjusting to the intense loading, rain and warm temperatures which have occurred during the past ten days. The potential for wet slides at the lower elevations is expected to be greatly diminished but not be completed gone. Naturally released wet slides are unlikely but some potential for human triggered wet slides may persist for another 24 hours. At the mid and upper elevations the potential for large, destructive avalanches to release naturally will also be greatly diminished. The potential for humans to trigger these very dangerous slides will persist. The general avalanches hazard is expected to be CONSIDERABLE.
