Cornices that formed mid-slope, indicating recent heavy wind-loading in the Bridger Range. Strong southwest wind between 12/18 and 12/19/21 drifted recent snow into hard, pillowy drifts. We avoided these drifts on steep slopes to give them a day or two to stabilize. Photo: GNFAC
21-22
These pillowy, hard drifts formed from strong southwest wind overnight between 12/18 and 12/19/21 in the Bridger Range. We saw minimal signs of instability, lke whumphing or cracking in these drifts, but avoided these features on steep slopes until they have more time to gain stability. Photo: GNFAC
In shallow areas near rock bands and wind-scoured slopes, we found a more developed weak layer of depth hoar. These shallow areas will be areas of concern when they get loaded by a larger storm or wind event. Photo: GNFAC
History Rock top of Upper Meadow
Date
Activity
Skiing
Dug two pits at northern end of the upper meadow just above a rollover. Slope was ~24 degrees, with a little over 30 degrees below the rollowver. Both pits had about 20 inches total, top 10" of new snow on top of a hard crust, faceted snow to the ground. Pit 1 ECTP 10, failing on the crust layer about 10" down. Pit 2 ECTP 0, failing while isolating the column on the crust. Both clean failures on the crust. Lower 10 inches was faceted, but had some cohesion. Several tracks on either side our pits. No sign of other pits. We skied the low angle terrain on the south end of the upper meadow.
Region
Northern Gallatin
Location (from list)
History Rock
Observer Name
Tony Thatcher
Bacon Rind - toward the bottom of the upper meadow
Date
Activity
Skiing
Snow pit - ECT24P with propagation about 1 meter down, very close to ground level. Newer snow well bonded to older snow
Region
Southern Madison
Location (from list)
Bacon Rind
Observer Name
Richard Ready
From obs 12/18/21: "95cm Snow depth at around 9400’ 40cm of new snow on early December ice crust Ectx18 Will have to see with more loading on early December interface if it becomes reactive All alpine terrain was heavily stripped from the wind."
GNFAC Avalanche Forecast for Sun Dec 19, 2021
Snowpack and Avalanche Discussion
<p>Strong west-southwest wind will drift snow from the past week into fresh slabs that skiers or riders could trigger. A person could also trigger avalanches of older drifts that formed over the past week. These wind slabs could range from 6 inches to 4 feet in depth. Avalanches are possible similar to those recently triggered by skiers and riders, such as a skier triggered slide at Bridger on Thursday (<a href="https://www.mtavalanche.com/node/25164"><strong>photos and details</strong></a>), a snowmobile triggered slide in the Taylor Fork (<a href="https://www.youtube.com/watch?v=PPHZEgnv4lM"><strong>video</strong></a&…;), and a skier triggered avalanche at Bacon Rind on Wednesday (<a href="https://mtavalanche.com/images/21/avalanche-bacon-rind-photo-15-dec-202…;). Be extra cautious of wind-loaded slopes, especially in terrain where the consequences being caught in a slide are high, like where you would be pushed into trees, over cliffs, dragged through rocks, or buried deeply in a confined gully.</p>
<p>Additionally, if you plan to ski or ride steep slopes dig to look for and evaluate the stability of buried weak layers. We have seen minimal evidence to indicate widespread buried weak layers exist, but with each load of new snow or fresh wind slabs we could see avalanches break deeper in the snowpack. Stay on the lookout for unstable buried weak layers, especially on slopes that held snow from October and early November.</p>
<p>Today, avalanches are possible to trigger and the avalanche danger is MODERATE.</p>
<p>Near Cooke City, strong west-southwest wind will drift snow into fresh wind slabs that skiers or riders could trigger. Older wind slabs 1-3 feet thick that formed over the past week are also possible to trigger, similar to a slab that snowmobilers triggered on Wednesday near Goose lake (<a href="https://www.mtavalanche.com/node/25168"><strong>details</strong></a>). On non-wind loaded slopes avalanches are unlikely. If you plan to ski or ride steep slopes dig to look for potential unstable buried weak layers, and carefully assess the stability of wind-drifted snow.</p>
<p>The avalanche danger is MODERATE on wind-loaded slopes and LOW on all other slopes.</p>
<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Upcoming Education Opportunities:
Get your avalanche brain ready for the season at one of the many classes listed on our education calendar, and list of upcoming events below. Don’t delay preparing and inspecting your avalanche gear. Get some tips from Dave Zinn in this Pre-Season gear check video.
Just below The top of alpine lift in trees to n of ski run
Date
Activity
Skiing
A couple quick hand hardness profiles for ya. 7700 feet (ish). Thanks for your work!
Region
Bridger Range
Location (from list)
Bridger Bowl
Observer Name
Chris Pruden