This is Alex Marienthal with pre-season information from the Gallatin National Forest Avalanche Center on Wednesday, November 27th at 7:30 am. This information is sponsored by World Boards and Uphill Pursuits. You can donate to The Friends of the GNFAC’s Fall Fundraiser HERE.
We will issue our next update on Friday morning and begin daily forecasts with danger ratings on Saturday.
New snow totals since our last update on Monday are:
0.2-0.3" SWE / 3-6” snow - Big Sky
0.3" SWE / 3” snow - Cooke City
0.1-0.2" SWE / 1-2” snow - Bridgers, Gallatins, Southern Madison, West Yellowstone, Island Park.
Winds have been out of the southwest and northwest at 5-25 mph with gusts of 25-45 mph. Temperatures this morning are single digits to teens F. The last couple days temperatures reached mid to high 20s F. The next couple days will be mostly sunny to partly cloudy with a small chance of up to an inch of snow tonight. Temperatures will reach low to mid-20s with overnight lows in the single digits to teens F. Wind will be westerly at 10-20 mph with gusts of 25-35 mph.
All Regions
Snow depths are 1.5-2.5 feet deep at weather stations with nearly 3 feet in higher locations. Snow that fell yesterday and last weekend was drifted into wind slabs which were human-triggered and broke naturally the last couple days. We saw examples of these wind slab avalanches breaking naturally on Saddle Peak on Monday (photo), and yesterday Big Sky ski patrol triggered multiple avalanches during mitigation work (obs and photo). Some of these avalanches broke on faceted snow just above the ground and some were confined to the recently drifted snow.
Wind slab avalanches can still be triggered, especially where new drifts grow from wind today and tomorrow. Be cautious of wind-loaded terrain and watch for blowing snow or cracking across the snow surface as a sign of fresh, unstable wind slabs.
Persistent slab avalanches breaking on weak faceted snow deeper in the snowpack are not a widespread hazard, but are a primary concern. Some slopes have a stronger snowpack without weak layers, but some slopes have slabs resting on facets and crusts near the bottom of the snowpack. So, do your homework before going into avalanche terrain. Recent avalanches at Big Sky are evidence of this problem as well as a few collapses near Cooke City and unstable test results in Bear Basin. Watch out for areas with shallower snow like Mark found on Lionhead on Saturday (video), OR slopes that harbour old October snow (elevations above 9,000’ and/or northerly facing).
Your observations are incredibly valuable. Contribute to our community’s knowledge by submitting your observations, and look through our observation page for additional information before your next backcountry adventure.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
Tuesday, November 26, 6-7 p.m. Free Avalanche Awareness at REI Bozeman.
Monday, December 2, 6:30 p.m. MAP community partnership night and 1-hr Avalanche Awareness, at MAP Brewing
Tuesday, December 10, 9 a.m.-3 p.m., West Yellowstone Avalanche Fundamentals: Motorized Guide Cert Course, Pre-registration required.
For an intro class with a field day, Register for our Avalanche Fundamentals course.
Friends of the Avalanche Center: Fall Fundraiser!
We’re still counting on your support and the online Fall Powder Blast fundraiser is 77% of the way to our goal. Please consider making even a small donation HERE or via Venmo
Bridger Bowl has backcountry conditions and there are no ski patrol services. Please steer clear of snowmaking equipment, chairlifts and snowmobiles, and respect posted signage, while they set up for the season.