Good morning. This is Eric Knoff with an early season avalanche information bulletin issued on Wednesday, November 23 at 7:30 a.m. This bulletin is sponsored by Cooke City Motorsports and Yamaha. Please remember that uphill traffic is not allowed at Big Sky or Moonlight Basin Ski areas. Uphill traffic is permitted at Bridger Bowl, but backcountry snow conditions exist. Our next bulletin will be issued Friday morning.
A warm and windy weather pattern has set up over southwest Montana. At 4 am mountain temperatures are ranging from the high 20s to mid 30s and winds are out of the WSW at 20-40 mph. This strong SW flow did produce snow showers in the southern ranges.
Since yesterday morning the mountains around Cooke City have picked up .7 inches of SWE totaling 4-5 inches of snow while the mountains around West Yellowstone picked up 2-3 inches of new snow. The northern ranges picked up a trace to one inch. Today, mountain temperatures will rise into the mid to high 30s F and winds will continue to blow 20-40 mph out of the WSW. Winds will gradually decrease this evening and Thanksgiving looks to be a warm and pleasant day.
The snowpack's character is being shaped by a variety of factors. The most concerning and widespread issue is the presence of weak facets at or near the ground. This setup is evident in many sections of our forecast area, and is especially apparent in the Hyalite drainage of the northern Gallatin Range (video1, video2).
Yesterday, Mark and I toured in the Mt. Blackmore area and discovered two natural avalanches that resulted from heavy wind loads. These slides broke 2-5 feet deep on facets near the ground (photo).
Doug found these same buried facets near Hyalite Peak over the weekend. This poor structure has been observed by groups in the Bridger Range (snowpit) and the Northern Madison Range (snowpit). The Big Sky Ski Patrol has triggered numerous avalanches in wind loaded terrain using explosives (photo) - these slides were also breaking on buried facets. In addition, touring parties have reported cracking and collapsing in the Southern Madison Range and Lionhead area near West Yellowstone.
We are lacking snowpack data from the mountains around Cooke City, but with new snow and strong winds it’s likely unstable conditions exist.
If you are heading into the backcountry be conservative. Stick to low angle slopes and avoid wind loaded terrain. Watch for obvious signs of instability and pay close attention to changing conditions. The season is still young – now is not the time to push it in avalanche terrain.
A special note to ice climbers: Hyalite’s high elevation gullies likely have faceted, unstable snow capped by thick wind drifts. Be extra cautious when climbing or hiking in these areas.
Mark will issue the next avalanche bulletin Friday Morning.
We are not issuing avalanche danger ratings due to limited snowpack data. We need your backcountry observations to help us. Any snowpack or avalanche information is especially valuable this time of year. If you get out, please drop us a line at mtavalanche@gmail.com or leave us a message at 587-6984.
Wednesday, November 30, BOZEMAN
Introduction to Avalanches with Field Course at MSU. Wednesday and Thursday evening lectures with a field course on Saturday. More info at http://www.mtavalanche.com/education/classes/workshops
Tuesday, December 6th Beartooth Harley, Billings – Basic 1 hr Avalanche Awareness
More info at http://www.mtavalanche.com/workshops/calendar
Tuesday, December 6th 406 Brewery, Bozeman – Basic 1hr Avalanche Awareness
More into at http://www.mtavalanche.com/workshops/calendar
Wednesday, December 7th, REI Bozeman – Basic 1 hr Avalanche Awareness
More into at http://www.mtavalanche.com/workshops/calendar
Wednesday, December 7th Livingston - Snowmobiler Introduction to Avalanches with Field Course, Wednesday and Thursday evening lectures with a field course on Saturday. More info at http://www.mtavalanche.com/education/classes/workshops
Thursday, December 15th West Yellowstone – Snowmobile Guides Course. Lectures on Thursday - field day on Friday. More info at http://www.mtavalanche.com/workshops/calendar