Very Dangerous avalanche conditions exist. Heavy snowfall and strong winds have resulted in conditions where natural avalanches are likely and humans venturing into avalanche terrain are very likely to trigger slides. These avalanches could involve new wind slabs and be small to large in size or they could be very large, involving deeper persistent instabilities within the snowpack. Travel in avalanche terrain is not recommended today. Teton Pass is closed this morning. WYDOT was able to trigger small avalanches in Hoback Canyon early this morning and then triggered a large slide in Glory Bowl on Teton Pass.
Slab avalanches involving buried weak faceted snow laying over hard crusts formed in late November could be triggered with depths of two to four feet on a variety of aspects. These slabs could be triggered by a single person, release naturally, or release after the initiation of a wind slab. Consequences of being involved in such a slide are likely to be very severe.
Heavy snowfall since yesterday afternoon, recent snow since Tuesday, and strong winds that have varied from the south to northwest have formed and continue to load wind slabs on a variety of aspects. These slabs will be very sensitive to human triggers today and could have depths to two feet. Once triggered these slabs could cause failure deeper in the snowpack.
( Discussion is generated from the previous day's afternoon forecast. )The National Weather Service has issued a Winter Weather Advisory for the area through Friday at 5pm. By that time, an additional four to ten inches of snow is expected in the mountains, with two to six expected in the valleys. Southwest winds are to be very strong overnight with averages near forty miles per hour and gusts in the sixties. During the day, winds are to lessen to twenty to thirty mile per hour averages.The general avalanche hazard is expected to be Considerable above 7500 feet if moderate snowfall occurs but could increase to High if overnight and morning snowfall is at the upper end of or exceeds the predicted snowfall amounts. Below 7500 feet the hazard could rise to Moderate if significant snowfall occurs there where weak snow lies on north aspects between 7000 and 7500 feet. Regardless of the final ratings, avalanche conditions will be DANGEROUS at a minimum. Skiers and riders will have the potential to trigger both wind slabs that have been being formed since Tuesday as well as deeper slabs involving the persistent weaknesses that have posed a threat for weeks on all aspects.
