New snow over the past 24 hours combined with strong winds have created slabs that will be sensitive to human triggers at the mid and upper elevations. 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. Approach avalanche terrain conservatively today, as the consequences of being caught may be severe. In the low elevations 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 summit 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 in the mid and upper elevations with suspicion and consider the consequences before stepping onto a slope. A report of a remotely triggered avalanche in the Southwest Trails area yesterday is a good example of the unpredictable and tenuous nature of this avalanche problem.
Snowfall is currently increasing in intensity. Expect snowfall to continue this evening and begin to taper off around midnight. By morning expect an additional 4-6” of snow in the Tetons, 1-3” on Togwotee Pass and 4-6” in the Southwest Trails/Grey’s River area. Lingering snow showers will continue into tomorrow and deposit another 1-3” of additional snow in all forecast zones. Temperatures will remain cold, with ridgetop locations remaining in the single digits and mid elevations in the teens. Winds will be out of the west at 20-25 mph overnight and lower into the 15-20 mph range during the day tomorrow.With the continuing trend of snowfall and wind over the next 24 hours, the avalanche danger will remain Considerable in the upper elevations of the Tetons and Southwest Trails areas. The danger may rise in the mid elevations of the Tetons from Moderate to Considerable. The danger will remain Moderate above 8,500 feet in the Togwotee Pass/Continental Divide area where less snow is forecasted. Wind slabs will range from 1-3 feet in depth and have the potential when triggered to step down to more deeply buried weak layers in the snowpack. The lower elevations will continue to have a Low danger rating where avalanche activity is unlikely except on very steep isolated terrain features. Conservative route finding and snowpack evaluation will be critical in avoiding involvement in avalanches.
