Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Sunday, February 23 at 7:30 a.m. Helio Collective and Buck Products, sponsor today’s advisory. This advisory does not apply to operating ski areas.
Overnight the mountains around Big Sky picked up 3-4 inches of new snow, 1-2 inches fell eslewhere. At 4 a.m. temperatures range between 5-10 degrees above zero F and westerly winds are blowing 10-20 mph with ridge top gusts reaching 40 mph near Big Sky and Hyalite. Today, temperatures will warm into the twenties F and winds will continue to blow 15-30 mph out of WNW. Snow will continue to fall through the day with 2-4 inches possible in the northern ranges and 1-3 in the south by this afternoon. Snowfall intensity will increase this evening with an additional 6-8 inches likely by Monday morning in the mountains around Bozeman, Big Sky and Cooke City. The mountains around West Yellowstone will see an additional 3-5 inches by tomorrow morning.
The Bridger Range Cooke City
The Bridger Range and mountains around Cooke City are a world apart, but have similar snowpack conditions. Both areas have received heavy amounts of snow and wind recently which has elevated the avalanche danger.
Fortunately, these areas lack widespread persistent weak layers, which has helped the avalanche danger drop quickly. Without much new snow and wind over the past twenty four hours, the snowpack has had time to settle down.
Yesterday, heavy traffic was observed on Saddle Peak south of Bridger Bowl. While this is pushing the limits, it's encouraging to hear no avalanches were triggered. Avalanche activity has also been quiet in the mountains around Cooke City.
Today, additional snow and wind will likely raise the avalanche danger. With plenty of low density snow available for transport, increasing winds will quickly form wind slabs on leeward slopes. Pay close attention to changing conditions and don’t be afraid to alter you plans if instability is on the rise.
Today, the avalanche danger is rated CONSIDERABLE on wind loaded slopes and slopes steeper than 35 degrees. Less steep slopes without a wind load have a MODERATE avalanche danger.
Southern Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone
The mountains near West Yellowstone, including the southern Madison Range have a widespread layer of facets buried two and half feet deep. This layer has been buried for over three weeks and is gradually gaining strength. Yesterday, Mark and his partners rode around Cabin Creek in the southern Madison Range and had no trouble finding this layer in snowpits. They did find it's taking harder force to get this layer to fail in stability tests, however; it is still propagating. Karl Birkeland found similar conditions in Bacon Rind on Friday.
It's encouraging to see this layer getting stronger, but a recent avalanche in the Lionhead area is potent reminder that now is no time to let your guard down. The slide in the Lionhead area occurred earlier in the week and partially buried two snowmobilers. Check out of the actual video footage posted on youtube.
Without a recent loading event avalanches are becoming harder to trigger. This is allowing skiers and riders to travel more confidently in avalanche terrain. This can be a dangerous set up. Don’t assume tracks on a slope mean its stable and always be thinking about the consequences of a slide.
Today, human triggered avalanches remain likely on slopes steeper than 35 degrees which have a CONSIDERABLE avalanche danger. Less steep slopes have a MODERATE avalanche danger.
Northern Gallatin Range Northern Madison Range
Both these areas have received significant snow and wind over the past week. This has created a variety of avalanche problems.
Today, the primary concern will be wind slabs. Winds are now gusting close to 40 mph out of the west at both the Hyalite weather station and near Big Sky. Upper elevation slopes facing the eastern half of the compass will be the most likely to hold wind deposited snow. With more snow and wind in the forecast, wind slabs will grow in size and distribution throughout the day.
A secondary concern is a layer of facets buried two feet deep. This layer is not the nuisance that it is to the south, but it continues to make an appearance. I would be most suspicious of southerly facing slopes where this layer sits on top of an ice crust. However, this layer should be assessed on all aspects and elevations.
Today, human triggered avalanches are likely on wind loaded slopes and slopes steeper than 35 degrees which have a CONSIDERABLE avalanche danger. Less steep slopes without a wind load have a MODERATE avalanche danger.
Beehive Basin Accident Report
The Beehive Basin Accident report is posted online and can be read here: http://www.mtavalanche.com/accident/14/02/18
I 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.
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