New snow over the past 24 hours combined with strong winds have created slabs that will be sensitive to human triggers above 8,000'. With additional snow and wind forecasted for this afternoon, expect these slabs to grow in size and sensitivity throughout the day. Avalanches involving the new snow have the potential to step down to older buried weak layers. A remotely triggered avalanche was reported yesterday in the vicinity of Stewart Peak in which the party deployed airbags and avoided being caught. See the Avalanche Event map for more detail. Approach avalanche terrain conservatively today, as the consequences of being caught may be severe. Below 8,000' avalanches are unlikely except in very steep isolated areas.
New snow combined with strong winds have created wind slabs in leeward starting zones. With current ridgetop wind speeds in the 40 mph range, expect loading to occur further down and across slopes than normal. These slabs will become larger throughout the day and grow to 2 feet in depth.
Weak layers of snow exist one to four feet below the surface. Avalanches involving these more deeply buried layers have the potential to be very large. Treat terrain with suspicion and consider the consequences before stepping onto a slope. The report of a remotely triggered avalanche in the Greys River area yesterday speaks to the unpredictable and tenuous nature of this avalanche problem.
( Discussion is generated from the previous day's afternoon forecast. )Snowfall has begun to increase in intensity this afternoon. By morning expect new snow amounts to be 3-5” in the Tetons, 1-3” on Togwotee, and 2-4” in the Southwest Trails. Snow will taper off for a brief period tomorrow morning and resume again by early afternoon. By evening tomorrow expect 24 hour totals to be 6-8” in the Tetons, 2-4” on Togwotee and 4-6” in the Southwest trails. Winds overnight will veer from the southwest to west and be in the 20-30 mph range. Temperatures will be slightly warmer but still remain in the single digits at ridgetops and high teens to low twenties in the valleys.With two more rounds of incoming precipitation in the next 24 hours, expect wind slabs to build in leeward starting zones. These new slabs will become more likely to trigger as the day progresses. This could help to increase the likelihood of persistent weak layers activating as well. Because of these factors, expect a modest rise in avalanche danger at the mid and upper elevations. The amount of new snow will determine the avalanche danger, with the upper elevations of the Tetons potentially rising to Considerable in the afternoon, and the mid elevations remaining Moderate. Expect the upper elevations of the Southwest Trails area to remain Considerable and the upper elevations of Togwotee to remain Moderate. The danger will remain Low in the low elevations in all forecast areas.
