We triggered this avalanche remotely from about 50 feet above the crown up on the ridge. The crown was 1-2' deep, 100' wide, and ran between 200 and 300 vertical feet through trees and cliffs. Another slide failed sympathetically at the same time, 100' down the ridgeline. The slides failed on a 40 cm thick layer of depth hoar, which composed half of the snowpack. Photo: GNFAC
18-19
We triggered this avalanche remotely from about 50 feet above the crown up on the ridge. The crown was 1-2' deep, 100' wide, and ran between 200 and 300 vertical feet through trees and cliffs. Another slide failed sympathetically at the same time, 100' down the ridgeline. The slides failed on a 40 cm thick layer of depth hoar, which composed half of the snowpack. Photo: GNFAC
Avalanche Details: Remote Triggered at Sunlight Basin (Taylor Fork)
Forecast link: GNFAC Avalanche Forecast for Thu Jan 31, 2019
Southern Madison, 2019-01-27
Forecast link: GNFAC Avalanche Forecast for Thu Jan 31, 2019
This snowpit from Bell Lake was dug by a level one avalanche class six days before a skier was killed in an avalanche on a slope nearby. Between the time this pit was dug and the time of the fatality, this area received steady snowfall which increased the weight and thickness of the slab overlying the weak interface at 130cm. Courtesy of Big Sky Backcountry Guides.
Skiers witnessed this avalanche slide on a low angle (30-32 degree) slope and break through very tight trees.
Avalanche Details: Large avalanche on low angle near Livingston
Forecast link: GNFAC Avalanche Forecast for Wed Jan 30, 2019
Out of Advisory Area, 2019-01-27
Forecast link: GNFAC Avalanche Forecast for Wed Jan 30, 2019
Skiers witnessed this avalanche slide on a low angle (30-32 degree) slope and break through very tight trees.
Avalanche Details: Large avalanche on low angle near Livingston
Forecast link: GNFAC Avalanche Forecast for Mon Jan 28, 2019
Out of Advisory Area, 2019-01-27
Forecast link: GNFAC Avalanche Forecast for Mon Jan 28, 2019
Large avalanche on low angle near Livingston
Other place
Out of Advisory Area
Code
SS-R3-D2
Elevation
9000
Aspect
NE
Latitude
45.60420
Longitude
-110.48900
Notes
From text: "this one was interesting because it was so low angle and in quite tight trees. We were in a zone south of Livingston today (1/26/19), near 9k’, NE aspect in dense timber not far from a ridge top. The slide may have been remote triggered by us skinning up or a large wind gust that came from the other side of ridge. We were touring up low angle terrain and had multiple large collapses on our ascent. We came to what was going to be our turn around point where my brother and I were discussing where we would rip skins and drop in. Before we proceeded into the timber on a 28deg slope we noticed a lot of tree bombs then saw the slide coming through the trees and taking out a couple of 10” diameter snags along the way. These trees were barely skiable due to how tight they were and the starting zone was only a hair over 30 deg. The crown we could see looked to be 3’, and 300’ wide. I’m unsure on the the distance it ran, but estimate 500-800 vertical ft. The main point I got from this slide was that we were crowding connected terrain, things are sliding at the very relaxed end of the slope spectrum, and don’t be lulled into a false sense of security in fairly dense timber."
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
R size
3
D size
2
Slab Thickness
36.0 inches
Vertical Fall
600ft
Slab Width
300.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
Snowmobile triggered avalanche near Cedar
Cedar Mtn.
Northern Madison
Code
SS-AMu-R3-D2
Elevation
8600
Aspect
NE
Latitude
45.22790
Longitude
-111.48900
Notes
From YCSP: "One of our patrollers spotted a snowmobile triggered avalanche on Cedar Mountain this afternoon. The patroller reported a track entering and exiting the path. The slope was NE facing at approximately 8,600’. It was difficult estimating the dimensions of the slide as the visibility was limited and we were quite a ways from the avalanche."
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
3
D size
2
Problem Type
Persistent Weak Layer
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
GNFAC Avalanche Forecast for Sun Jan 27, 2019
Snowpack and Avalanche Discussion
<p>The mountains throughout our advisory area have a variety of poor, unstable snowpack structures. On some slopes the bottom 2 feet of the snowpack is sugary, weak and unsupportive (<strong><a href="https://www.youtube.com/watch?v=zHramxEhjO8&index=2&list=PLXu51…;). Other slopes have a stronger foundation, but weak, sugary facets are sandwiched between that foundation and 3-4’ of recent snow above.</p>
<p>Regardless of which poor snowpack structure exists, recent steady snowfall and strong wind have overloaded these weak layers past their breaking point. Since January 16 (last 11 days) the mountains have received 3-4’ of snow equal to the weight of 2.5-4” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE) (<strong><a href="https://www.mtavalanche.com/weather/wx-avalanche-log">Weather Log</a></strong>).</p>
<p>Natural and human triggered avalanches occurred each of the last 9 days with <a href="https://www.mtavalanche.com/avalanche-activity">ten avalanches reported</a> yesterday. Two of these yesterday were skier triggered in the Bridger Range. One skier was caught and fully buried during the slide, but ended up on top of the debris (<strong><a href="https://www.mtavalanche.com/node/19852">details</a></strong>). The other was not caught (<strong><a href="https://www.mtavalanche.com/node/19873">details</a></strong>). Big Sky ski patrol triggered a large avalanche that broke 3-10’ deep on weak snow at the bottom of the snowpack (<strong><a href="https://www.mtavalanche.com/node/19845">details</a></strong>). This is the first of this type (deep slab) they have triggered this season, which shows recent steady loading has pushed deeper layers in the snowpack to break.</p>
<p>Sadly, on Friday a skier was killed in an avalanche in the Tobacco Roots (<strong><a href="https://www.mtavalanche.com/node/19826">details and photos</a></strong>), there was a snowmobiler killed in Idaho, and a snowmobiler buried and missing in Utah (<strong><a href="https://avalanche.state.co.us/accidents/us/">CAIC database</a></strong>). Through the western U.S. buried weak layers and recent snow have created dangerous avalanche conditions. This year the snowpack is begging us to be patient and choose conservative objectives for our backcountry tours. Before you go to the backcountry do your homework. Carefully plan safe routes through low angle terrain, and view our <strong><a href="https://www.youtube.com/playlist?list=PLXu5151nmAvRNl9kuY3DxfWN1qiU7IeX…;, <strong><a href="https://www.mtavalanche.com/photos">photos</a></strong>, and <strong><a href="https://www.mtavalanche.com/avalanche-activity">avalanche activity</a> </strong>pages for a more thorough understanding of the snowpack.</p>
<p>Today large and dangerous avalanches are easy to trigger and could break naturally. Avalanche danger is <strong>CONSIDERABLE</strong>.</p>
<p>If you get out and have any avalanche or snowpack observations to share, contact us via our <u><a href="https://www.mtavalanche.com/node/add/snow_observation">website</a></u>, email (<u><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></u>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Avalanche Fatality Tobacco Roots
On Friday four skiers were caught in an avalanche while ascending a steep forested slope in the Tobacco Root Mountains. Two skiers grabbed trees and were able to self, the other two skiers were swept downhill. One skier was seriously injured, the other died from trauma. The GNFAC will issue more information once it becomes available. Our deepest condolences go to the family and friends of the victim. Preliminary details and photos.
Natural Avalanche on the West Side, Bridgers
Truman Gulch
Bridger Range
Code
N-R3-D2-O
Elevation
7400
Aspect
N
Latitude
45.80770
Longitude
-110.94600
Notes
Bridger Bowl Ski patrol snapped a photo of this natural slab avalanche on the west side of the Bridgers near Truman Gulch. Photo: BBSP
Number caught
0
Number buried
0
Number killed
0
Trigger
Natural trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year