Good Morning. This is Dave Zinn with the Gallatin National Forest Avalanche Forecast on Wednesday, February 19th at 6:45 a.m. Today’s forecast is sponsored by the Yellowstone Club Community Foundation and Gallatin County Search and Rescue. This forecast does not apply to operating ski areas.
The mountains around Bozeman and Cooke City received 1-2” of new snow in the last 24 hours with none for the rest of the advisory area. Mountain temperatures are in the single digits above and below zero F and winds are 5 mph from the west to north. Skies will clear today with temperatures in the low to mid-teens F with light winds at 5-10 mph from the west to north.
New snow and strong winds last week increased the avalanche hazard. This weekend numerous natural and human triggered slides occurred across the Bridger, Madison, and Gallatin Ranges and in the mountains around Cooke City. Reports are still coming in. Yesterday, a human triggered avalanche north of Cooke City broke 3-4' deep and 100' across a small slope (photo and details). Several natural avalanches on heavily wind loaded slopes on Wilson Peak likely failed Monday night. On Monday at Buck Ridge, a snowmobiler triggered a large avalanche more than four feet deep that failed on weak snow near the ground (details). These recent events are clear evidence that human triggered avalanches are still possible. Go to our avalanche activity page to learn more about this avalanche cycle.
As high pressure settles into the advisory area, it will be harder to trigger avalanches on deeply buried weak layers. Persistent weak layers, such as the widely distributed weak, sugary snow near the ground, are tricky. Signs of instability like natural avalanches and collapsing will not be forthcoming today and you may get stable test results but keep the big picture in mind. This weekend the mountains reached a tipping point and large, destructive avalanches occurred on this layer and within the new snow. Doug wouldn’t trust the snowpack at Mount Ellis on Monday (video) and, in Cooke City, this deeply buried weak layer kept us making relatively conservative decisions even though the mountains and stability tests presented us with no signs of volatility (video).
In the mountains around West Yellowstone, stability has improved. There has been no avalanche activity reported in the area in the last ten days. Riders are out and climbing hills and not triggering slides. We rode up Denny Creek and Lionhead Ridge two times in the last week and a half and were pleasantly surprised both times by the lack of avalanche activity, the absence of signs of instability following a significant loading event and that weak snow near the ground is gaining strength (Ski Hill video, Denny Creek video). The avalanche danger is LOW and human triggered avalanches are unlikely. Continue to follow standard avalanche safety protocols by carrying all avalanche rescue gear, assessing steep slopes for isolated instabilities, and exposing only one person at a time to potential hazards.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.
Every Friday and Saturday, Snowpack Update and Rescue Training. Friday, 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
March 4, 1-hr Avalanche Awareness. 6-7 p.m. at REI.
February 22, 1-hr Avalanche Awareness. 7-8 p.m. at West Yellowstone Holiday Inn.
On Saturday, three motorized snowbikers were caught in an avalanche in Colorado and two were killed. We are deeply saddened by this accident. You can read the preliminary accident report here. Please take the time to learn what we can from this and all accidents. Stay safe if you are getting into the mountains today.