23-24

Sticking to Slopes less than 30 degrees

Date
Activity
Skiing

For longevity in the backcountry, base terrain selection decisions on indicators of instability rather than stability and consider the big picture rather than the small one. That is what we did in Beehive/ Bear Basins today (2/15). With an avalanche warning in place, a foot of new snow, a natural avalanche across the valley, and a snowpack that has proven to be reliably unstable this season, we ignored stable test results (ECTN teens and 20s) and absence of observed cracking/ collapsing. We executed our plan to avoid terrain over 30 degrees. Additionally, with the season's history of triggering avalanches from long distances away, we were cautious about traveling below steep slopes.

We met an avalanche class who were working on snowpits closer to the ridgeline. The group experienced one large collapse and had a number of test results that propagated on the weak faceted snow low in the snowpack. 

Region
Northern Madison
Location (from list)
Bear Basin
Observer Name
David Zinn

Cooke City Obs

Date

Sun came out for for a bit around 2pm when I was on top of Henderson Mountain. Got a good look at East facing Miller, South Face of Crown Butte, west side of Sheep Mountain and did not see any recent avalanche activity.  10-12"  new snow in town and on the mountain as of 2pm today. 

Region
Cooke City
Observer Name
Ben Zavora

GNFAC Avalanche Forecast for Thu Feb 15, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>It is very dangerous in the backcountry. We have issued an Avalanche Warning and the danger is rated HIGH on all slopes throughout our forecast area.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Mere inches of new snow are triggering avalanches naturally. With strong southwest wind, slopes will be loaded and drifted which adds more weight to our fragile and unstable snowpack. Yesterday, Ian and I rode into Taylor Fork and toured Sage Basin to Cabin Creek. We saw a large natural avalanche that broke a couple days ago. It propagated 700+ feet wide. On an adjacent slope was a smaller but deep avalanche, likely triggered from the bottom of the slope by a snowmobiler on Tuesday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30741"><span><span><span><strong><span…;). Ian succinctly stated in his </span></span></span></span></span></span><a href="https://youtube.com/shorts/MOhXUC0dK8Q"><span><span><span><strong><span…;, “The equation is simple: recent avalanches, plus people triggering avalanches, plus more snow, means the avalanche danger will spike.” It’s not very complicated.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Stay out of avalanche terrain and stay away from the bottom of slopes. To help, use the 30-20 rule: measuring with an inclinometer, any slope steeper than 30 degrees is avalanche terrain, and runout zone angles should be under 20 degrees (</span></span></span></span></span></span><a href="https://youtu.be/_d5_vlY-bjg"><span><span><span><strong><span><u><span>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). </span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Triggering avalanches from below or adjacent to a slope is scary and dangerous. A whumpf is the sound of a weak layer collapsing which can travel onto a steep slope and avalanche above you. Typically this type of instability is short lived and rare, but not this year. Dave got surprised on Monday when he triggered an avalanche at Buck Ridge from afar on the flats (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30721"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=7F9kBArjRDc"><span><span><span><strong>…;

<p><span><span><span><span><span><span>In the last 10 days, the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/avalanche-activity"><span><span><span><stro… activity log</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> has over 50 entries of avalanche activity and other signs of instability. It is sobering. We are lucky no one has died in an avalanche. Going in the backcountry is like entering enemy territory with insurgents hiding and watching.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

Remotely triggered slide in Sage Basin

Taylor Fork
Southern Madison
Code
AMr-R1-D1
Latitude
45.06070
Longitude
-111.27200
Notes

On 2/14/23 we saw a slide in Sage Basin that appears to have been remotely triggered by riders yesterday from ~100 ft away. Couldn't get a great view of it but it appeared to break in two pockets ~50 ft apart, each at least 25 ft wide and running 30 vertical feet. 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
1
D size
1
Slab Thickness
36.0 inches
Vertical Fall
30ft
Slab Width
25.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural avalanches in Sage and Sunlight Basins

Taylor Fork
Southern Madison
Code
SS-N-R2-D2
Latitude
45.06070
Longitude
-111.27200
Notes

On 2/14/23 we saw two recent natural avalanches along the headwall of Sage Basin and one in Sunlight Basin. Date is estimated based on how much snow is on the debris. All of the slide looked to be 2-3 ft deep, breaking on the early season weak snow at the bottom of the pack. One of the slides in Sage broke ~700 ft wide.

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Slab Thickness
36.0 inches
Vertical Fall
100ft
Slab Width
700.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year