This is Dave Zinn with the avalanche forecast for Tuesday, December 17th, at 7:00 am. This information is sponsored by Werner Wealth Management, Upper Yellowstone Snowmobile Club and Cooke City Motorsports. This forecast does not apply to operating ski areas.
Mountain temperatures are in the teens F this morning, with 10-15 mph winds from the northwest to southwest.
24 Hour Snowfall Totals:
- Big Sky - 7-12” (0.3-0.6” Snow water equivalent - SWE)
- Bridger Range, Cooke City, West Yellowstone, and Island Park - 4-6” (0.4-0.8” SWE)
- Northern Gallatin Range - 2” (0.2” SWE)
Today, high temperatures will be in the 20s F, with 5-10 mph winds from the west to southwest. The mountains around Cooke City, West Yellowstone and Island Park will receive an additional 2-4” of snow by tomorrow morning, with a trace to 2” near Big Sky and Bozeman.
All Regions
Dangerous avalanche conditions exist across the advisory area. New and wind-drifted snow are loading weak layers buried 1-2 feet deep and human-triggered avalanches are likely. Reduce or eliminate exposure to slopes steeper than 30 degrees until the snowpack has time to adjust to recent snowfall. Traveling in and around avalanche terrain requires careful snowpack evaluation, cautious route-finding and conservative decision-making.
Three-Day Storm Totals:
- Bridger Range, Cooke City, Island Park and Big Sky - 15-22” (1.3-2.0” SWE)
- West Yellowstone, Taylor Fork and Hyalite Canyon - 8-12” (0.6-1.2” SWE)
Wind slab avalanches failing 1-3 feet deep are likely today. Avoid slopes with visual clues of recent drifting and commonly wind-loaded areas near ridgelines, below cornices and in gullies. Indicators of wind slab instability include recent avalanche activity, shooting cracks and a stiffening of the snow surface. Yesterday, my partner and I visited the site of a wind slab avalanche in Cooke City that broke 3 feet deep and 100 feet wide on Sunday as a group skied past (video). Recent snow and wind had reloaded the slope, and it was ready to avalanche again. Expect a similar story throughout the advisory area.
On Sunday, riders in the West Yellowstone and Island Park areas reported persistent slab avalanches failing on buried weak layers near Two Top (details and photos), and a group on Mount Blackmore triggered a large whumphing collapse (details). Weak layers buried 1-2 feet deep exist across the forecast area (Cooke City, Buck Ridge, Taylor Fork videos). Recent avalanche activity, whumphs, and shooting cracks are bullseye indicators of instability.
Notable Recent Avalanche Activity Since Sunday (all reported activity on log):
- Many natural avalanches on Saddle Peak and in Argentina Bowl (details)
- Remotely triggered wind slab avalanche on Henderson (details, GNFAC ob)
- Persistent slab avalanche near Island Park (details)
- Collapsing, cracking, and a remotely triggered storm snow avalanche in Beehive (details, details)
- Skier triggered storm slab avalanche on The Throne (details)
Avalanche danger is CONSIDERABLE on all slopes.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
Thursday, Dec 19 and Saturday, Dec 21, Companion Rescue Clinic at REI in Bozeman and History Rock. 6 to 8 pm on Thursday, 10 to 2 pm on Saturday.
Friends of the Avalanche Center: Fall Fundraiser!
We’re still counting on your support and the online Fall Powder Blast fundraiser is 79% of the way to our goal. Please consider making even a small donation HERE or via Venmo
We are sad to report that yesterday A motorized snowbiker was killed in an avalanche in the mountains northwest of Cascade, ID. Preliminary info here.