Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, February 13 at 7:30 a.m. Today’s advisory is sponsored by the friends and family of Caleb Acker who passed away in an avalanche in Truman Gulch last year. This advisory does not apply to operating ski areas.
During the past twenty four hours no new snow has fallen over our forecast area. This morning, mountain temperatures are in the teens under mostly cloudy skies and winds are blowing out of the WNW at 5-15 mph. Today, temperatures will warm into the mid twenties and winds will remain light out of the WNW at 5-15 mph. A weak weather disturbance will bring a chance of snow showers to the mountains through the day. A trace to one inch is possible by this afternoon. A better chance of snow will arrive later tomorrow.
The mountains around Cooke City:
Conditions remain touchy in the mountains around Cooke City. Yesterday, skiers remotely triggered an avalanche on a SE facing slope around 9,500 ft (photo). A large natural was also observed on the south face of Mt Abundance, the same slope that ripped to the ground eleven days ago. When natural activity and remote triggering take place, it’s a clear indication very unstable conditions exist.
It was also noted slopes that avalanched earlier in the season are avalanching again. Unfortunately, this may be a trend that sticks around – something to consider when riding in the backcountry.
While the snowpack works overtime to adjust, it will remain sensitive to the weight of a skier or rider. Slopes with a southerly aspect appear to be the most active, but all slopes will be capable of producing avalanches.
Today, human triggered avalanches remain likely and the avalanche danger is rated CONSIDERABLE.
The Madison Range, southern Gallatin Range and the Lionhead area near West Yellowstone:
The snowpack resembles a crooked old house with a weak foundation (snowpit). It has a rickety structure but without a significant load, it has entered a fragile state of balance. Applying load to this snowpack would be like building an additional level on the already shaky house - potentially causing the whole thing to come crashing down.
Yesterday, I skied in the southern Madison Range and found a snowpack that made me cringe. However, my partner and I did not experience any signs of instability and observed no natural activity, a sign the snowpack is well adjusted (video).
Triggering an avalanche today will require finding the right spot on the right slope. Areas where the snowpack is thinner, mainly in steep rocky terrain or around thin scoured areas will be likely trigger points. Although the avalanche danger is settling down, now is not the time to push it in big terrain. If an avalanche is triggered, it will likely break deep and carry severe consequences.
Today, heightened avalanche conditions exist on specific terrain features and the avalanche danger is rated MODERATE.
The northern Gallatin Range and the Bridger Range:
The snowpack structure between the northern Gallatin Range and Bridger Range is dissimilar. The northern Gallatin Range has a deeper more stable snowpack, while the Bridger Range has a pack that is shallow and weak. Despite their differences, the threat of triggering an avalanche remains the same.
The most likely areas where a skier or rider will find unstable snow will be in steep rocky terrain. On Saturday a skier triggered and was caught in a small slide up the Flanders drainage in Hyalite. The slide occurred after the skier jumped 3-4 feet onto a small patch of snow in rocky terrain. The snow released carrying the skier with it. Fortunately the skier escaped unharmed.
This is a fine example that human triggered avalanches remain possible in steep terrain where the avalanche danger is rated MODERATE. Less steep slopes have a LOW avalanche danger.
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.
Bozeman
FREE 1-hour Avalanche Awareness at REI on Thursday, February 16 at 6:30 p.m. For more information call REI at 406-587-1938.