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Extreme Conditions

post #1 of 25
Thread Starter 

Logan UT is currently in extreme avy conditions. Friday I was at the resort skiing a hike to in bounds area. I think this was perhaps the first time people had been out there this season... There was constant whomphing ever turn and fracturing all around me the entire run. A couple of times I stopped and then felt myself drop 6" while still on the surface of the snow.  Nothing slid as its not steep enough to start a slide. Twas a very interesting experience.

post #2 of 25

Things are definetly interesting out here. We saw lots of fractures at Copper yesterday and I even had a section about 15 feet wide and 8" slide out on me with fractures extending another 15 feet on either side on the section that slide.

post #3 of 25

I think it will be interesting to see how this plays out but I suspect we haven't seen the worst of it yet.  I think skiers and boarders are starved for fresh snow and there will be some very poor decisions made in the next few days.  Stay safe out there.

post #4 of 25

No kidding.

 

I have zero (count 'em) turns so far this year.  I had nearly 30 days by this time last year.

 

There are going to be a lot of people out there taking chances on snowmobiles and skis because of pent-up demand.  I will be very surprised if we don't see somebody killed out of this.

 

XC skiing today... perhaps will get my first (meadow skipping) tour tomorrow.

 

Pretty freaking frightening.Avalanche danger.jpg

post #5 of 25

From CAIC:

 

'The second and third avalanche fatalities of the season in Colorado occurred on Sunday. One accident was at Vail Mountain on a closed ski run. The second involved a small avalanche in a gully feature at the Winter Park ski area.'

 

Like I said I saw several large fractures on closed runs yesterday at Copper. This almost makes me want to start carrying a beacon especially after that micro slide I set off which just accented the unstability in the snow to me

post #6 of 25
Quote:
Originally Posted by lonewolf210 View Post

Things are definetly interesting out here. We saw lots of fractures at Copper yesterday and I even had a section about 15 feet wide and 8" slide out on me with fractures extending another 15 feet on either side on the section that slide.



Where were you?

 

[eta: not saying this as an accusation, I'm genuinely curious]

post #7 of 25
Quote:
Originally Posted by segbrown View Post



Where were you?

 

[eta: not saying this as an accusation, I'm genuinely curious]



Trees near the bottom between collage and bouncer

post #8 of 25

What is a "gully feature"???

 

Did that happen in the Vasquez Cirque?

post #9 of 25
Quote:
Originally Posted by Vitamin Ski View Post

What is a "gully feature"???

 

Did that happen in the Vasquez Cirque?



I read somewhere it was on Trestle.  -- here you go

 

http://www.thedenverchannel.com/news/30279345/detail.html

post #10 of 25
Quote:
Originally Posted by Vitamin Ski View Post

What is a "gully feature"???

 

Did that happen in the Vasquez Cirque?



 Think of what happens when a wide shallow river funneling into a narrow constriction. A relatively small slide or even sluff can become deep and deadly very quickly in a gully. 

post #11 of 25
Thread Starter 
Quote:
Originally Posted by markojp View Post



 Think of what happens when a wide shallow river funneling into a narrow constriction. A relatively small slide or even sluff can become deep and deadly very quickly in a gully. 


Otherwise called a terrain trap.

 

post #12 of 25
Quote:
Originally Posted by lonewolf210 View Post



Trees near the bottom between collage and bouncer


RIght by that steep little pitch on skier's right at the bottom of Bouncer?

 

post #13 of 25
Quote:
Originally Posted by segbrown View Post


RIght by that steep little pitch on skier's right at the bottom of Bouncer?

 



Yep it's skiers right off of bouncer adn skiers left off of collage

post #14 of 25
Quote:
Originally Posted by mountaingirl1961 View Post

No kidding.

 

I have zero (count 'em) turns so far this year.  I had nearly 30 days by this time last year.

 

There are going to be a lot of people out there taking chances on snowmobiles and skis because of pent-up demand.  I will be very surprised if we don't see somebody killed out of this.

 

XC skiing today... perhaps will get my first (meadow skipping) tour tomorrow.

 

Pretty freaking frightening.Avalanche danger.jpg



Your prediction, unfortunately, is correct:  

http://utahavalanchecenter.org/accident_west_couloir_1282012

 

post #15 of 25

Yes, always an interesting experience, however, you were smart to stay off the steep. But, be careful in those conditions when skiing near trees because even a slow slide can push/crush you against a tree.
 

Quote:
Originally Posted by tromano View Post

Logan UT is currently in extreme avy conditions. Friday I was at the resort skiing a hike to in bounds area. I think this was perhaps the first time people had been out there this season... There was constant whomphing ever turn and fracturing all around me the entire run. A couple of times I stopped and then felt myself drop 6" while still on the surface of the snow.  Nothing slid as its not steep enough to start a slide. Twas a very interesting experience.



 

post #16 of 25
Thread Starter 
Quote:
Originally Posted by Vince F View Post



Your prediction, unfortunately, is correct:  

http://utahavalanchecenter.org/accident_west_couloir_1282012

 


Yea, I heard about that. What a bummer.

 

I was out in the BC yesterday on mellow terrain in the Bear Lake Mountains (~100 miles NNE from the central wasatch). On the NE facing line ~8400' there is a 4' slab of strong heavy snow over about 1' of sugar. Stability actually looked ok where I was, but if you were to start a slide it would be all over. 

post #17 of 25

Quick question for the snow science guys. This weekend I was digging around in the snow near a groomed snowmobile trail and noticed about a 1/4 inch thick layer of what I would describe as almost ice. This was about a 1.5' down and was obviously the crust formed from the long period of no snow.

 

My question is how does this play into stability. Is this layer a major problem or is it the more sugary snow it sits on top of?A combination of both?   

post #18 of 25

The sugary snow layer is the biggest problem that could allow the above layers to be unstable and slab slide...and you are right, also a combination of both.

post #19 of 25

So if my understanding is correct that sugary layer is what will allow it to slide but that but that hard layer will be particularly good at sliding and bring about slab cohesion resulting in large avalanches rather tha smaller isolated ones?  

post #20 of 25

snow.layers2-2.jpgsnowprotocol_fig03.gif Ice is slick,anything on top of it will slide when triggered.

post #21 of 25

Given the conditions, even small isolated ones can occur, given the steepness of the slope. I've seen small slides happen in the trees.
 

Quote:
Originally Posted by lonewolf210 View Post

So if my understanding is correct that sugary layer is what will allow it to slide but that but that hard layer will be particularly good at sliding and bring about slab cohesion resulting in large avalanches rather tha smaller isolated ones?  



 

post #22 of 25
Quote:
Originally Posted by Racer View Post

Given the conditions, even small isolated ones can occur, given the steepness of the slope. I've seen small slides happen in the trees.
 



 


I didn't mean none existent just less likely. I am just trying to understand the mechanics behind what CAIC is saying:

 

"Slabs are sitting atop weak underlying snow across the Vail-Summit zone. The slabs are stiffening, making them harder to trigger. The downside is slabs that do release are generally becoming larger and more destructive. Triggering large, dangerous avalanches remains likely on many slopes. These avalanches can be triggered remotely from low angle terrain well below starting zones."

 

post #23 of 25
post #24 of 25
Thread Starter 
Quote:
Originally Posted by lonewolf210 View Post


I didn't mean none existent just less likely. I am just trying to understand the mechanics behind what CAIC is saying:

 

"Slabs are sitting atop weak underlying snow across the Vail-Summit zone. The slabs are stiffening, making them harder to trigger. The downside is slabs that do release are generally becoming larger and more destructive. Triggering large, dangerous avalanches remains likely on many slopes. These avalanches can be triggered remotely from low angle terrain well below starting zones."

 


Human triggered avalanche require the snow to be in a delicate balance. The snow must be stable enough that the snow is not naturally sloughing off or fracturing under its own weight. And the snow must also not be so stable that it cannot physically be triggered by a human sized object.

 

In relation to the hard slab avalanches being described, a shallowr slab is relatively easy to trigger by a human sized object, but due to less cohesive shallow slab, they tend to entrain relatively little snow volume and thus would be less destructive.

 

As the hard slab builds in thickness and strength it becomes harder to trigger by a human sized object. At the same time the increasing strength and cohesiveness, if you do some how trigger a slide,  you are going to release a much larger more destructive avalanche.

 

post #25 of 25
Quote:
Originally Posted by tromano View Post

 

As the hard slab builds in thickness and strength it becomes harder to trigger by a human sized object. At the same time the increasing strength and cohesiveness, if you do some how trigger a slide,  you are going to release a much larger more destructive avalanche.

 


 

Another good reason to ski gently on suspect surfaces

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