Travel in avalanche terrain is not recommended today. Two days of significant loading have created very dangerous avalanche conditions. Natural activity is likely in the upper elevations all day as well as in the mid elevations in the afternoon. Large avalanches in the upper elevations have the potential to travel into the mid elevations. Wind slabs, deep persistent slabs and loose snow avalanches are all on the list for potential problems today. Be aware not only of the terrain you are travelling in but what sits above you. In the lower elevations expect newly formed slabs to build in steep isolated areas and be easy to trigger.***Special Announcement***The Wyoming Department of Transportation will close WY 22/Teton Pass today, Jan. 6, at noon for avalanche mitigation.U.S. Highway 191/189 at Hoback Canyon will be closed at 6 p.m. today, also for avalanche mitigation. Closures could occur earlier if weather conditions or avalanche danger worsens.Highway travelers and backcountry users are advised to plan accordingly.
West and southwest winds combined with over 30” of new snow over the past 3 days have created unstable slabs in wind loaded terrain. These slabs will grow in size throughout the day and be 1-4 feet in depth. These slabs have the potential to release naturally and will be very sensitive to human triggers.
Weak layers of snow buried 4-7 feet below the surface hold the potential to produce very large avalanches. Avalanches triggered at this depth will have great destructive force and run potentially long distances. These avalanches could fail under the weight of a single person or the initiation of a wind slab. Avoidance of this problem is key today. Treat any terrain above 8,500 feet with suspicion and to hold the potential to produce avalanches on these layers.
High precipitation intensity rates will allow the buildup of enough loose snow in steep sheltered areas to be their own problem. Loose snow avalanches have the potential to carry people into terrain traps such as cliffs, gullies and trees. Pay attention to the terrain below you and consider the consequences of being carried and losing control in steep terrain in the mid and low elevations.
A Winter Storm Warning issued by the NWS will remain in effect until 11pm tonight. By morning expect another 4-6” of snow in the Tetons, 2-4” on Togwotee and 4-6” in the Grey’s River. Light snowfall will continue tomorrow, with 24 hours totals of 8-10” in the Tetons, 3-6” on Togwotee and 6-8” in the Grey’s River. Winds will be out of the west at 25-35 mph. Temperatures will remain mild, with ridgetops in the low twenties and valley locations hovering around the freezing mark overnight and into the afternoon tomorrow.While precipitation will ease slightly, loading will continue overnight and through the day tomorrow. Along with mild temperatures, this will likely keep the avalanche danger in the high range in upper elevations and considerable in the mid and lower elevations. The snowpack in all three forecast areas has undergone dramatic change. Weak interfaces within the recent snow as well as deeper weak layers simply need time to adjust.
