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GNFAC Avalanche Forecast for Fri Dec 22, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Human triggered avalanches are likely today in Cooke City. It’s been a week and a half since the last snowfall, but the snowpack remains unstable. It is unusual for the danger to remain elevated for so long without new snow. This is a reflection that conditions are unusual. The snowpack structure is remarkably poor. Signs of instability remain widespread and we do not trust the snowpack (see Dave’s recent videos </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29628"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Rv7NkQmnUnE"><span><span><span><strong>…;). Don’t get complacent. Take heed and continue to avoid avalanche terrain. If you choose to ride steep slopes, expect to trigger avalanches. The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Weak snow is widespread but stability is slowly improving. The last reported avalanches were on Sunday, with a skier triggered slide at Lionhead (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29586"><span><span><span><strong><span…;) and a snowmobile triggered slide on Buck Ridge (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29614"><span><span><span><strong><span…;). Fewer slopes are showing the propensity to avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29603"><span><span><span><strong><span… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). On many slopes slabs are breaking down and the whole snowpack is weakening, which is bad news for stability once it starts snowing again (maybe tonight?), but for now means avalanches are becoming less likely. Dig before riding steep slopes to make sure you haven’t found one of the lingering areas of instability with a substantial slab over the weak snow at the bottom of the snowpack. Also, remember that the snowpack is still thin and highly variable, so give yourself a big margin of error in both your snowpack assessment and terrain choices.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Human triggered avalanches are possible and the avalanche danger is MODERATE.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Expect snowfall beginning tonight to bring changing avalanche conditions this weekend.</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.

Beehive tour

Date
Activity
Skiing

HS 55, ECTN11@33, 28 degree slope, 80 degrees E. Upper snowpack is faceting, lower snowpack is depth hoar. Surface is sun affected and has breakable melt freeze crust on all non shaded slopes. No obvious signs of instability observed. 

Region
Northern Madison
Location (from list)
Beehive Basin

Natural avalanche, hyalite peak

Date
Activity
Skiing

Pretty sure that’s an avalanche. Thought it might be goat tracks or something but you can see were some debris went through the slope below the cliff. The left side looks like it could’ve gone recently, but I couldn’t really tell. 

Region
Northern Gallatin
Location (from list)
Hyalite Peak
Observer Name
Jake Schack

Do Your Homework in Cooke City

Date
Activity
Skiing
Snowmobiling

We did a large loop north of Cooke City today. Signs of instability were easy to come by but we saw more of a mixed bag of test results. We started our day near Henderson Mountain, where, while ascending, we felt a few collapses. Our first stability test had ECTX results but lacked a slab on top of the weak snow near the bottom. We stopped 100' down-slope and saw different results, ECTP15 and ECTN15 above a crust. We rode across the valley, saw a very poor snowpack structure below Miller Ridge, and got varied results (ECTP15, ECTN15 x 3). Regardless of test scores, I have difficulty trusting such a weak snowpack structure.  

Finally, we rode back to Scotch Bonnet to see how things had changed since Sunday when Alex was there. The poor structure Alex saw on Sunday was still there, with continued unstable test results (ECTP16 on weak snow above a crust).

My partner and I felt better about the conditions today than yesterday at Woody Ridge. The weak structure around Cooke City is widespread. Safe travel requires careful snowpack evaluation, cautious route finding, and conservative decision-making. 

Region
Cooke City
Location (from list)
Multiple locations
Observer Name
Zach Peterson

GNFAC Avalanche Forecast for Thu Dec 21, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>The snowpack in Cooke City continues to show more instability than other mountain ranges in our advisory area. Yesterday, Dave and his partner were “surprised by the abundant signs of instability nine days after the last measurable snow…My partner and I felt that triggering an avalanche would be likely if we ventured into avalanche terrain. I am worried, and we are avoiding steep slopes.” His </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29628"><span><span><span><strong><span…; from yesterday and Alex’s </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29573"><span><span><span><strong><span…; from Sunday, outline their worry. It is still dangerous in the backcountry with whumpfing, cracking, and poor test scores being seen day after day.&nbsp;&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The snowpack in Cooke City remains unstable and the danger is rated </span></span></span></span></span></span><span><span><span><strong><span><span>CONSIDERABLE</span></span></strong></span></span></span><span><span><span><span><span><span>.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>From Bozeman to Big Sky to West Yellowstone and Island Park, the snowpack is weak on all slopes and unstable on a few. Snow on the ground changes with time, and the longer we go without new snow, the weaker it becomes. On slopes with a cohesive slab perched on top of this weaker snow (i.e. wind-load), we will get collapses (whumpfing), sometimes cracking and occasionally avalanches. On Sunday, Ian found a small slide up Buck Ridge that was triggered by sledders using the slope to test stability, which was a good idea (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29614"><span><span><span><strong><span…;).&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>With time stability is slowly improving. Our snowpit tests take more force to break layers and avalanche activity is decreasing. However, over the last few days, collapsing in Lionhead and whumpfs and cracking in Bacon Rind are signs of lingering instability.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>I do not trust most slopes in our advisory area until I dig and test to determine if a slab and weak layer combination exists (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29603"><span><span><span><strong><span…;). It is still possible to trigger avalanches and the danger is rated </span></span></span></span></span></span><span><span><span><strong><span><span>MODERATE</span></span></strong></span></span></span><span><span><span><span><span><span>.&nbsp;</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.