23-24

Cracking and collapsing north of Cooke City

Date
Activity
Skiing

Yesterday (1/9) touring north of Cooke City I felt some large collapses and cracking on a heavily wind loaded, mid elevation slope. There was about 4-6 inches of new snow that fell throughout the day. 
 

Region
Cooke City
Location (from list)
Zimmer Creek
Observer Name
Jake Mundt

GNFAC Avalanche Forecast for Wed Jan 10, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>The avalanche danger is HIGH in the southern mountains and an Avalanche Warning has been issued. Since Friday these mountains have gotten a little bit of snow each day totaling 12-18” (1” </span></span></span></span></span></span><a href="https://avalanche.org/avalanche-encyclopedia/snowpack/snowpack-observat…;). Wind in the last 36 hours has blown at all elevations further loading slopes. The snowpack is historically weak which is outlined in this </span></span></span></span></span></span><a href="https://youtu.be/K_t6Fi6wUC4"><span><span><span><strong><span><u><span>… compilation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. Yesterday I was in Lionhead and found very poor stability in our snowpit at 8,000’, widespread cracking and collapsing at 8,300’ feet, and we intentionally triggered a 1,000’ wide avalanche at 8,600’ (</span></span></span></span></span></span><a href="https://youtu.be/QNkJeGFSPYs"><span><span><span><strong><span><u><span>…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29836"><span><span><span><strong><span… and observation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Our advice is simple: Do not go into or underneath avalanche terrain. Avalanches can be triggered from far away and they will be large and deadly. </span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The mountains around Bozeman and Big Sky have a couple feet of weak, faceted snow that is capped by 4-6” that fell since Saturday night (.4-.6” </span></span></span></span></span></span><a href="https://avalanche.org/avalanche-encyclopedia/snowpack/snowpack-observat…;). Strong and gusty wind has swirled and loaded slopes at all elevations. The interface between recent snow and older snow is unstable. Typically, 6” of snow over 4 days is nothing to worry about, but these are not typical times.&nbsp; My uncertainty regarding stability is high and I am worried. Given the wind and new snow, triggering avalanches is likely, especially slopes with a wind drift. Notch your travel plans back and be extra cautious and vigilant. Cracking, collapsing and avalanche activity are obvious signs to stay away from steep slopes. Today is not a day to push your luck. If you need evidence of the instability, check out our </span></span></span></span></span></span><a href="https://www.youtube.com/playlist?list=PLXu5151nmAvSH326zVaU9KXJAPtvkIt-… videos</span></span></u></span></strong></span></span></span><span><span><span><span><span><u><span><span> </span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… page</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is rated CONSIDERABLE. </span></span></span></span></span></span></p>

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Remotely Triggered Avalanche in Lionhead

Lionhead Ridge
Lionhead Range
Code
SS-ASr-R3-D2-O
Elevation
8600
Aspect
NE
Latitude
44.71450
Longitude
-111.31800
Notes

While approaching Lionhead Ridge skiers intentionally triggered an avalanche on the steep E, NE facing terrain below the ridge. This likely happened on a buried layer of surface hoar. Lower down widespread cracking was observed that extended well in font of the skiers and on a less steep slope cracking in all directions 50' wide. Along the ridgetop cracking continued and sections of cornice fell and avalanched below. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
100ft
Slab Width
1000.00ft
Weak Layer Grain type
Surface Hoar
Weak Layer Hardness
F
Slab Layer Grain Type
Precipitation Particles
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Skier Triggered and Natural Avalanches in Hyalite

Mt Blackmore
Northern Gallatin
Code
SS-AS-R1-D1
Aspect
E
Latitude
45.44440
Longitude
-111.00400
Notes

A skier at Mt. Blackmore saw multiple natural avalanches and one skier triggered avalanche. These likely happened earlier in the day or the day prior, 01/07. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
R size
1
D size
1
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year