Good Morning. This is Eric Knoff with early season avalanche and weather information from the Gallatin National Forest Avalanche Center on Friday, November 23rd. This bulletin is sponsored by The Friends of the Avalanche Center and Knoff Group Real Estate. This bulletin will be updated tomorrow.
Since yesterday afternoon the mountains near West Yellowstone picked up 5-7” of new snow. The Bridger Range and mountains around Cooke City received 4-5” while the Big Sky area squeezed out 2-3”. This morning, it’s still snowing lightly and temps range from the teens to mid-20’s F. Winds are blowing 20-40 mph out of the W-SW. Today, temps will warm into the upper 20’s to low 30’s F and winds will continue to blow 20-40 out of the W-SW. There will be a slight break in precipitation today before a stronger storm impacts the area tonight and tomorrow. By morning the southern ranges and mountains around Big Sky will likely see 6-8” of new snow while the mountains around Bozeman will see 4-6”. Temps will drop into the teens tonight and winds will remain moderate to strong out of the W-SW.
For those choosing to escape the Black Friday frenzy by heading into the hills, keep in mind both Bridger Bowl and Big Sky Ski Resorts are open. If you venture into the backcountry, carefully assess the new snow-old interface, especially on slopes loaded by west-southwest winds. Yesterday, the Big Sky Ski Patrol saw both natural and human triggered avalanches during control work. It only took a few inches of new snow combined with strong winds to create cohesive slabs that failed easily. A skier up Hyalite also observed a natural avalanche that likely occurred yesterday (photo).
The culprit for such touchy conditions is a weak layer of near surface facets or surface hoar that formed during the recent spell of high pressure. On Wednesday, I found this layer in Hyalite and Doug and Alex also found it in Cooke City (video, video, photo). This weak layer is now capped and loaded by new and wind-blown snow. We lack snowpack data from the mountains around West Yellowstone, but we assume the snowpack is weak in that area as well.
As the avalanche danger continues to rise, now is not the time to push it in avalanche terrain. This means keeping slope angles lower than 35 degrees and avoiding lower angle slopes attached to steeper slopes above. In addition to conservative terrain management and careful snowpack assessment, it’s imperative that everyone carries proper rescue gear and knows how to use it. With more snow and wind on the way, expect dangerous avalanche conditions through the weekend.
New this season, we added hyperlinks to the Weather and Avalanche Log and a new Menu item <Avalanches and SnowPits> with information on avalanche activity and incidents.
If you get outside send us an observation via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
November 26, MSU Snow and Avalanche Workshop, 5-9pm at MSU SUB Ballroom A
November 29, 30 and Dec 1, 2or 8, Intro to Avalanche w/ Field Day, more info here
COOKE CITY
Every Friday and Saturday, Rescue Training and Snowpack Update. Friday 6:30-7:30 p.m. location TBD. Saturday anytime between 10-2 @ Round Lake.
Practice with your rescue gear, and test your partner’s skills. Put fresh batteries in your beacon and check your shovel and probe for any damage, and replace them if needed.