Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, December 10 at 7:30 a.m. Today’s advisory is sponsored by World Boards and Madison River Brewing Company in partnership with the Friends of the Avalanche Center.
Overnight 2-4 inches of snow fell in most mountain locations. At 4 am temperatures are in the single digits to low teens and winds are blowing 15-30 mph out of the WNW with gusts reaching close to 40 mph. Today, temperatures will warm into the 20s F and winds will continue to blow 15-30 from the WNW. A northwest flow will remain over the area today and tonight. Light bands of snow will continue to move through southwest Montana providing an additional 1-3 inches of snow by tomorrow morning.
Today, the main avalanche concern will be wind slabs. Strong west to northwest winds over the past 12 hours have transported the recently fallen, low density snow onto leeward slopes. Winds slabs should stay confined to the new storm snow, but have to potential to step down to deeper layers in the snowpack.
Yesterday, Doug and I traveled south of Bridger Bowl to the Football Field. We found a surprisingly thin and weak snowpack. A layer of small grained facets buried beneath a pencil hard wind slab propagated with medium force during stability tests (video, photo). Skiers also found unstable snow in Red Canyon in the southern Madison Range. They experienced cracking and collapsing and got unstable results during stability tests. A large natural avalanche was also observed by a skier outside of Cooke City (photo). We can’t forget that Mark found a layer of buried surface hoar in the Taylor Fork last Wednesday.
Buried facets won’t be found on all slopes, but are starting to show a more widespread distribution. Snow has now has fallen seven out of the last eight days, giving these weak layers little time to adjust. Digging a snowpit to evaluate structure and stability on the slope you plan to ride is a great idea. Also, pay attention to signs of instability such as cracking or collapsing. If these signs are present, it’s best to avoid slopes steeper than thirty degrees.
For today, the hazard will remain elevated on wind loaded slopes which have a CONSIDERABLE avalanche danger. On slopes without a wind load, the avalanche danger is rated MODERATE.
Doug will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.
Snowmobiler Introduction to Avalanches with Field Course in Billings at Hi-Tech Motor Sports on December 12 and 13, 6-9 p.m. and the field course on January 20 in Cooke City. Sign up for this class HERE
Snowmobiler Introduction to Avalanches with Field Course in West Yellowstone on December 20 and 21. Sign up for this class HERE.
FREE 1 hour lectures:
December 12, REI in Bozeman, 6:30 p.m.