From obs: "On the way up on the West facing ridge we found facets to the ground below 17cm with that large ice layer on top. Given the low density of the new snow sitting on top, we ascended to Bear Basin-Middle Ridge via the ridge and lower angle gully. Photo is taken at 2860m, East facing on the ridge between Beehive Basin and Middle basin. Layers in the photo are easily distinguishable in the photo. We decided not to ski into Middle Basin and descended back the way we came up. On the ridge winds were blowing East ~15mph and cornices were present.
21-22
GNFAC Avalanche Forecast for Fri Dec 17, 2021
Snowpack and Avalanche Discussion
<p>Peak instability from this week’s storm has passed, but don’t let your guard down just yet. You could still trigger an avalanche today. Over the past week nearly 3 ft of snow fell in the southern portions of our advisory area with around a foot in the north. </p>
<p>Especially in the southern regions, this storm pushed the snowpack to its breaking point. On Wednesday, Dave and I triggered a small avalanche in the Taylor Fork on the first steep slope we approached while still 100’ away and saw numerous larger avalanches that broke 2-3 ft deep naturally during the storm (<a href="https://www.youtube.com/watch?v=PPHZEgnv4lM"><strong><u>video</u></stro…;, </strong><a href="https://mtavalanche.com/node/25158"><strong><u>details</u></strong></a&…;). A skier nearby at Bacon Rind triggered an avalanche from the flats above a steep slope (<a href="https://mtavalanche.com/node/25151"><strong><u>details</u></strong></a&…;, <a href="https://mtavalanche.com/images/21/avalanche-bacon-rind-photo-15-dec-202…;). Yesterday, a skier triggered and was caught in an avalanche that broke 8” deep near The Apron at Bridger Bowl (the ski area is closed and backcountry conditions exist). Luckily, nobody was injured (<a href="https://www.mtavalanche.com/node/25164"><strong><u>photos and details</u></strong></a>). </p>
<p>Without active heavy loading, the snowpack is working to adjust to the weight of the storm snow, but the added force of a skier or rider may still be enough for it to break and avalanche. Our primary concern remains avalanches breaking beneath the new snow, especially in areas with recent drifting. We also still have some early season uncertainty about the deeper weak layers, so dig and evaluate them if you’re considering riding in avalanche terrain. </p>
<p>Human triggered avalanches are possible today and the avalanche danger is MODERATE.</p>
<p>On wind-loaded slopes, you could trigger an avalanche 1-3 ft deep beneath this week’s new snow. Look out for these wind-loaded slopes and signs of instability such as cracks shooting out in front of you. Pay close attention to the snow beneath your feet or sled as last night’s new snow may obscure the obvious visible signs of wind loading. Avalanches are unlikely to fail on deeper weak layers until they get loaded more heavily. </p>
<p>On wind-loaded slopes the avalanche danger is MODERATE because human-triggered avalanches are possible. On other slopes the avalanche danger is LOW.</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><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), 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.
Skier triggered and caught near The Apron at Bridger
Bridger Bowl
Bridger Range
Code
SS-ASu-R2-D1.5-I
Elevation
7700
Aspect
NE
Latitude
45.81560
Longitude
-110.92300
Notes
On 12/16/21 A skier in a group of three triggered and was caught in an avalanche near The Apron at Bridger Bowl. The ski area is closed and backcountry conditions exist. Nobody was injured.
From e-mail: "We had a group of three skiing up at the Bridger Apron today. We skied a more main slope in the field north of the slope with hidden couloir , snow was very stable and has been getting a lot of tracks. For a second run we skinned up the main slope under hidden and started our run in the trees slightly south of this slope. Not many tracks over there and not a good enough evaluation of the snowpack. We were planning on skiing a northeast facing chute through the trees that had very nice looking snow similar to what we had skiied earlier. I skiied in and had about 3 amazing turns, definitely partially due to the wind loading at this aspect . After three turns my feet were taking out from under me and I got caught in a slide keeping skis perpendicular to slope for 15-20’. This avalanche carried me rapidly and cleared the snow to the rocks below in which I was able to come to a hault and watch the rest of the sluff sl slide ast me. After looking at the conditions after, this windy as aspect eemed to have a very faceted layer about 8” down that acted as the crown. No injuries, a lost ski pole in the runout which extended down the slope maybe another 40’. The wind scoop on top and seeing these facets should have been a clear sign prior to skiing. Must be more diligent even in areas of high traffic. When dropping in to ski on first turn or so I remember hearing a possible whumpf."
Number caught
1
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
2
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Slab Thickness
8.0 inches
Images
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
On 12/16/21 A skier in a group of three triggered and was caught in this avalanche next to The Apron at Bridger Bowl. The ski area is closed and backcountry conditions exist. Nobody was injured.
On 12/16/21 A skier in a group of three triggered and was caught in this avalanche near The Apron at Bridger Bowl. The ski area is closed and backcountry conditions exist. Nobody was injured.
Avalanche Details: Skier triggered and caught near The Apron at Bridger
Forecast link: GNFAC Avalanche Forecast for Sun Dec 19, 2021
Bridger Range, 2021-12-16
Forecast link: GNFAC Avalanche Forecast for Sun Dec 19, 2021
GNFAC Avalanche Forecast for Thu Dec 16, 2021
Snowpack and Avalanche Discussion
<p>This week’s storm total in the Lionhead area, and Southern Madison and Southern Gallatin Ranges reached 32” of snow with 2.7-2.9” of <a href="https://missoulaavalanche.org/2021/01/what-is-swe-snow-water-equivalent… water equivalent</a> (SWE). Yesterday, in the Taylor Fork, Ian and I triggered a small avalanche on the first steep slope we approached while still 100’ away. We saw many natural avalanches that broke 2-3’ deep during the storm (<a href="https://www.youtube.com/watch?v=PPHZEgnv4lM"><strong>video</strong></a>…;, </strong><a href="https://mtavalanche.com/node/25158"><strong>details</strong></a>). A skier nearby in Bacon Rind triggered an avalanche on a steep slope while he was in the flat terrain above (<a href="https://mtavalanche.com/node/25151"><strong>details</strong></a>, <a href="https://mtavalanche.com/images/21/avalanche-bacon-rind-photo-15-dec-202…;). On Sunday, I triggered a large collapse in a drift of snow on Lionhead Ridge (<a href="https://www.youtube.com/watch?v=Vo9-92FngRA&list=PLXu5151nmAvT1nrM2…;). This is all the information we need to make decisions right now, steep slopes loaded by nearly 3’ of snow since Saturday are unstable and need time to stabilize before we consider entering avalanche terrain.</p>
<p>Human-triggered avalanches are likely, and the danger is rated CONSIDERABLE on all slopes.</p>
<p>The Northern Gallatin, Northern Madison and Bridger Ranges received 8-10” of snow equal to 0.6-0.9 <a href="https://missoulaavalanche.org/2021/01/what-is-swe-snow-water-equivalent…; Tuesday night. Bridger Bowl Ski Patrol noted 17” of snow at the top of the Bridger Chairlift. The Big Sky Ski Patrol triggered “very reactive” slabs at the interface between the old and new snow during routine avalanche mitigation. Skiers noted a small slide on a road cut on their way up the East Fork of Hyalite Creek (<a href="https://mtavalanche.com/images/21/small-slab-along-hyalite-road"><stron…;) and skiers at Bridger Bowl, where backcountry conditions exist, noted a couple of small natural slides. Two days ago, a skier triggered a small wind-slab avalanche near <a href="https://www.mtavalanche.com/node/25142"><strong>the Ramp</strong></a>. Snow fell on a generally stable snowpack and our primary concern is new snow avalanches especially in areas with recent drifting. Slides breaking on deeper <a href="https://www.mtavalanche.com/images/21/thin-snowpack-hyalite"><strong>we… layers</strong></a> are unlikely without additional loading (<a href="https://www.youtube.com/watch?v=8yJ1-BzM8Eg&list=PLXu5151nmAvT1nrM2… video</strong></a>).</p>
<p>Human-triggered avalanches are possible and the danger is MODERATE.</p>
<p>Cooke City received 17-20” of snow since Saturday equal to 1.7” <a href="https://missoulaavalanche.org/2021/01/what-is-swe-snow-water-equivalent…; with winds consistently transporting snow into slabs. Avoid these wind-loaded slopes where skiers yesterday observed cracking and collapsing and got unstable test results. Turn around if you see similar indicators of instability today. Avalanches are unlikely to fail on the deeper weak layers that Alex and Ian described in last week’s videos but dig down and test these layers to avoid any nasty surprises (<a href="https://www.youtube.com/watch?v=1Nt5LOMI1PQ"><strong>Cooke City video 1</strong></a>, <a href="https://youtu.be/O29XGDZBL8c"><strong>Cooke City video 2</strong></a>).</p>
<p>Human triggered avalanches are possible on wind-loaded slopes where the danger is MODERATE and unlikely on all others where the danger is LOW.</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.
Natural and remotely triggered slides in Taylor Fork
Taylor Fork
Southern Madison
Code
SS-AMr-R2-D1.5-I
Aspect
NE
Latitude
45.06070
Longitude
-111.27200
Notes
A small avalanche (15ft wide, 1-2ft deep) was triggered from 100 ft away on 12/15 at the divide between Sage and Carrot Basins in the Taylor Fork. It broke beneath the recent storm snow.
6 other slides broke naturally during the storm along the Sage Basin ridge line. These slides broke 2-3 ft deep beneath the storm snow and ran 50-100 ft.
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
2
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness
30.0 inches
Attached Videos
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
Natural avalanche in Taylor Fork that broke 100ft wide, 2-3 ft deep, beneath the recent storm snow. Appears to have failed towards the end of the storm (likely 12/15/21). Photo: GNFAC