Up to 14 inches of news snow with over an inch of moisture has fallen in the mountains since early yesterday morning. Increasing winds are forecast to create areas of blowing snow at all elevations. These winds will rapidly increase the avalanche hazard and create dangerous conditions. Natural avalanche activity is likely on a variety of aspects at all elevations. Large avalanches are likely and very large avalanches are possible. Travel in avalanche terrain is not recommended during periods of high hazard.
Increasing southwest winds be will rapidly loading a snowpack with poor structure. Slab avalanches up to three feet in depth are very likely to release naturally or be easily triggered by humans at the mid and upper elevations. Similar events are likely on a variety of aspects at the lower elevations with depths from 1 to 2 feet.
Today's loading event could cause large to very large slab avalanches to release naturally on persistent weak layers that formed earlier in the season. These dangerous and destructive slab avalanches could be 3 to 5 feet deep and may run long distances.
( Discussion is generated from the previous day's afternoon forecast. )After a brief lull, another more impactful storm will move into the area. Snowfall will increase after midnight and become heavy from around 2AM to 11AM. This system will bring another 6 to 12 inches of snow to the region. It will be accompanied by steadily increasing southwest to west winds. On Monday winds will frequently gust to 50 to 60 miles per hour along the high ridges throughout the daylight hours. Valley winds will steadily increase to sustained speeds of 20 with gusts to 30 miles per hour from sunrise into the afternoon. The snowfall and winds are forecast to decrease around sunset. Temperatures will be in the teens in the mountains and in the upper teens to upper 20s in the valleys. There were two avalanche fatalities in the Rocky Mountain region yesterday. A snowmobiler died west of Choteau, Montana and a backcountry skier died near Red Mountain Pass in southwest Colorado.Very strong sustained winds and new snow will create dangerous avalanche conditions at all elevations in all of our forecast areas. Blowing and drifting snow will cause whiteout conditions and rapidly load a snowpack with poor snow structure and persistent weak layers. Natural avalanche activity is likely on a variety of aspects at all elevations. Large slab avalanches are likely and very large slab avalanches are possible. The Wyoming Department of Transportation will close the highway over Teton Pass at 3AM for the purpose of conducting avalanche hazard mitigation efforts. Avalanches may impact highways on that road and in the river canyons during this storm. On Monday the general avalanche hazard is expected to high in the Teton and Greys River/Southwest Trails areas. Travel in avalanche terrain is not recommended. Large to very large natural avalanches are likely. The general avalanche hazard is expected to be considerable in the Togwotee Pass area where conditions will also be dangerous. Large human triggered avalanches are likely and large natural avalanches are possible. Expert terrain analysis skills are essential for safe travel in this area.
