Very dangerous avalanche conditions exist. New snow and strong southwesterly winds have added load to a snowpack that has buried weak layers. Additional snowfall and strong winds that are to veer to the northwest during the day will further stress these weaknesses. Travel in avalanche terrain is not recommended as natural avalanche activity is likely and human triggered avalanches are very likely. Avalanches could occur in the form of wind slabs at higher elevations or as persistent slabs at all elevations, involving older weak snow that lies close to the ground.
New and recent snow could be triggered as wind slabs in steep terrain above 8000. These sensitive soft slabs were formed during southwest to west winds over the last three days and could have depths to two feet. Changing wind direction will continue to load and increase the sensitivity of these slabs even as snowfall diminishes this afternoon.
Persistent weak layers of faceted snow exist throughout the backcountry. Above 9000 feet these weaknesses are less prevalent and less sensitive but if triggered can be very large hard slabs with depths of three to five feet. They will be more sensitive at the mid elevations where they could be hard or soft and have depths of two to four feet. At the low elevations the structure of the snowpack is very poor. At these elevations, slabs will be sensitive and are likely to involve faceted snow to the ground. The sensitivity of these slabs will also increase as additional snowfall and strong winds further load avalanche starting zones.
A ridge of high pressure will be over the area tonight and through Wednesday. Expect morning fog and inversion conditions with valleys starting out near or below zero and mountains starting near ten degrees. Highs in the mid-twenties are forecast for all elevations. The general avalanche hazard will be Considerable above 7500 feet in the Southwest Trails and Teton areas and Moderate below that elevation. In the Togwotee Pass area, the danger will be Moderate. Wind slabs and persistent slabs could be triggered in all areas. The recently formed wind slabs could have depths to two feet at higher elevations. The chance for human triggered avalanches involving persistent weak layers of faceted snow exists at all elevations. Although less likely to initiate, very large hard slab avalanches could be triggered at higher elevations with depths to five in the Teton and Southwest Trails areas and to three feet in the Togwotee Pass area. At mid and lower elevations, the triggering of avalanches by a single person is more likely but they will also be smaller in size, particularly at the low elevations.
