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Slim

Making fresh tracks
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Hi,
Wondering if there are any (former) patrollers on here who can explain Inbounds Avalanche Danger to me.

This past Monday we skied Alta and Snowbird. Avalanche danger was rated “considerable’ for the Upper Cootnwoods backcountry. Most noted danger was windslab. It continued snowing and blowing very hard all day.

If I had been skiing in the backcountry, i would have avoided any terrain over 30 degrees, since windslabs were likely. I especially would have avoided any wind deposits I noticed.

But inbounds, although some terrain was closed, we skied more than a foot deep new snow, much of it wind deposited. Some of it steeper terrain.

Some terrain was marked “avalanche terrain, enter through gates only”. Other terrain was unmarked.
So how do I decide what terrain to ski or avoid inbounds? When is extra cation warranted? Do we consider that patrol checked this terrain(even the untracked stuff in the trees?) and considered it safe enough? Or am I expected to judge it for myself?




58F95B95-9185-462B-B351-2A0102C6B7A7.jpeg
D1937987-B992-46C7-BAE6-5007B4ECDE34.jpeg
 

Posaune

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Patrol checks this stuff every day after a storm. They set avalanches with explosives and by skiing them off. Your odds have been improved and they make their best guess that it is safe and leave it open, but there is no guarantee that an avalanche won't occur. You pay your money and you take your chances.
 
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Slim

Slim

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Note that I am note trying to “blame” anyone and am happy to accept personal responsibility. I also don’t expect any 100% ironclad guarantees.

What I want to know is:
  1. How much judgement should I exercise myself?
  2. What are the guidelines for inbounds avalanche danger? In other words, how much safer is it than in the backcountry, and what terrain do you consider acceptable inbounds, that you would not consider acceptable in the back country?
 

Posaune

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Avalanches happen all the time in the backcountry. A person needs to become educated by reading and taking classes to really prepare themselves to understand the danger on a given day at a given place. Avalanches happen extremely seldom in open inbounds areas. If it's open, it's almost certainly safe from big slides, but again, there are no guarantees when humans and nature are both involved.
 

jmeb

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If it's open, it's almost certainly safe from big slides, but again, there are no guarantees when humans and nature are both involved.

I think this is a good summary. Questions that ask to quantify the difference I don't think are possible -- we don't have appropriate stats or data collection mechanisms to give a clear answer.

Basically: you can be reasonably confident you won't be caught in a big slide. However, small wind slabs or storm slabs are more possible. These can still be big enough to knock you down, or push you into a tree (or tree well) or over a cliff etc. And if you're really unlucky, a bigger release can happen.

Things you can do to better your chances:

- Don't ski avalanche terrain alone.
- Ski avalanche terrain one at a time if you're uncertain.
- Wear a beacon so patrol can find you.
- Carry a beacon / shovel / probe if you want to be able to rescue a friend.
 

mikel

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Patrol checks this stuff every day after a storm. They set avalanches with explosives and by skiing them off. Your odds have been improved and they make their best guess that it is safe and leave it open, but there is no guarantee that an avalanche won't occur.

^this but I did remove the last sentence


Things you can do to better your chances:

- Don't ski avalanche terrain alone.
- Ski avalanche terrain one at a time if you're uncertain.
- Wear a beacon so patrol can find you.
- Carry a beacon / shovel / probe if you want to be able to rescue a friend.

^and this

Sounds like you had some real concerns and questions. Just me, but I would have gone to Patrol and had a chat. They will answer your questions/concerns. Yes if it's inbounds and open the terrain has probably been checked but double checking and confirming with Patrol can be a good thing. Talking about conditions is a good thing. If there are concerns that makes you uncomfortable then I wouldn't ski it.
 
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Slim

Slim

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@Posaune and @jmeb ,
I know/agree the things you mention above.
It’s not quite what I want.
Perhaps I am phrasing this poorly.

Let’s try it this way:
On that day, if it had been in the backcountry, no one would have claimed that it was a reasonable level of risk to ski 35 degree, leeward slopes above a terrain trap:
34F3963E-41EA-4FB0-8558-F6AA480725B8.jpeg

But that is what we are doing here, in open terrain at Snowbird.
The fact that they opened it, mean that patrol considers this to be an acceptable level of risk, right? SO they must use a different set of risk assessment than what we learn as backcountry travelers. This is further born out by the fact that the avalanche forecast specifically states: “this forecast does not apply to ski resorts”.

If you are a skipatroller, that day, what would you tell me if I talked to you about entering this terrain:
  1. Have fun! Of course there’s a risk but it’s not super dangerous. Watch out for the cliffs!
  2. You know you are entering avalanche terrain? Maybe ski on at a time and stop in safe spots.
  3. Are you sure you want to ski this today? Why don’t you wait until tomorrow? Well, if you have too, make sure you have a buddy spotting you for a possible rescue.
Which of those 3?
 
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Slim

Slim

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Sounds like you had some real concerns and questions. Just me, but I would have gone to Patrol and had a chat. They will answer your questions/concerns. Yes if it's inbounds and open the terrain has probably been checked but double checking and confirming with Patrol can be a good thing. Talking about conditions is a good thing. If there are concerns that makes you uncomfortable then I wouldn't ski it.

Absolutely! I would have, but this came up after the fact. At the time I was happily “lemminging” around the resort, enjoying the steep and deep!

I sent some pics to my buddy, he sayd: “you’re skiing 35 degree stuff at “considerable” level, what the heck?” My reply was: “no this wasn't backcountry, this was inbounds” Then we talked more and it got me thinking.
especially in this case, I can see how persistent slab is less of a problem inbounds, but all day snow and wind meant wind slab was the biggest issue and that still happens,

So that got me thinking, and I wondered if there were any patrollers around who could explain how they would like skiers to think about avalanche risk inbounds.

I will ask next time I’m in the mountains during elevated danger, but I’m impatient...
 

Analisa

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What I want to know is:
  1. How much judgement should I exercise myself?
  2. What are the guidelines for inbounds avalanche danger? In other words, how much safer is it than in the backcountry, and what terrain do you consider acceptable inbounds, that you would not consider acceptable in the back country?

Like most conversations about avalanche risk, the answers are really complex thanks to the fact that they're nuanced and personal. In the example about the 3 options that a patroller would tell you about a specific run, I don't think they'd commit to any of those 3 answers (or at least the avalanche professionals I know would not - they'll talk about observations and problems in the snowpack all day, but if anyone asks is X safe, their answer is always no). Are the avalanche problems deep persistent slabs or wind slabs? If the latter, are you and your buddies strong at identifying patterns in snow and what those patterns say about the transport and loading zones and which areas of a run to avoid? There are so many variables involved that it's really impossible to compare two scenarios unless you know every detail about the people, terrain, weather, and existing snowpack problems.

For me personally, I gather that if terrain is open and a named run, the risks are quite low. I make adjustments if the avalanche forecast is high and it is storming throughout the day (vs. overnight, where it's easier to do control work without the resort being in operation). Likewise, I'll give myself a buffer if I'm considering any sort of "grey area" from an inbounds/out of bounds perspective, like a series of ridgelines above a run that are within the resort boundary markers and controlled to protect the runs below them, but there's also s sign that you're leaving the area boundary for part of the hike that includes a minimum fine for rescue and, until this year, included a beacon checkpoint.
 

Sibhusky

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Having had an avalanche pass right in front of me a few years back when Pacobillie was here, my assessment is that the risk is low but ya never know for sure. Certainly if it has rained the night before I'm not going to pass under any steep slopes that never get groomed.
 

Rod9301

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jmeb

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But that is what we are doing here, in open terrain at Snowbird.
The fact that they opened it, mean that patrol considers this to be an acceptable level of risk, right? SO they must use a different set of risk assessment than what we learn as backcountry travelers.

I don't think it is necessarily a different set of risk assessment, it's that the assessment of the two produces very different outcomes. The reason for the different determinations is because while the terrain is the same (slope, aspect, trees, traps), the snowpack is entirely different. Even if they are physically close, the amount of skier traffic inbounds yields a very different snowpack structure compared to out of bounds. Even if that out of bounds place gets "lots of traffic" its an order of magnitude different than most inbounds terrain. Its a bit hard to appreciate just how different the snowpack structure is inbounds vs backcountry unless you've dug pits in both terrain.

Patrol probably saw that and assessed that the only likely danger is storm or wind slab. Those are real risks, but nothing compared to a storm or wind slab in the backcountry that has the potential to step down to a persistent week layer.
 

SSSdave

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After receiving 90 inches over a few days with the top few feet snow that fell during temps in low teens, the snow was as good as it ever gets even down at 6k feet. As a tree skier, yesterday saw numbers of scary inbounds short steep terrain features in obscure places ski patrols never work that after most storms is ho hum but when new snow gets deep could colapse. Also potential hollow spots between close trees, normally narrow little gullies that could also be hollow, especially where small post storm stream flows are below. It isn't all about obvious big steep slopes inbounds.
 

stan51

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Snow safety is a matter of probabilities. When patrol bomb and ski cut, they are pushing the probability of an avalanche downwards, but you can never eliminate the risk altogether as long as there is a snowpack. If the chance of something occurring is one in a thousand, that one event can happen.

In the areas I am most familiar with, patrol does bomb or ski cut the small chutes as well as the larger open steep slopes. The choice of control routes is based on past history... what has historically slid and where control activities have produced slides in the past. Sometimes on a given day there is no response from control activities, sometimes the response is unexpectedly large. Rarely, but sometimes, control activities will not produce any slide, but skiers will. Listen to the podcast at: https://utahavalanchecenter.org/blog/43654 . It is truly enlightening.
 

Ken_R

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Hi,
Wondering if there are any (former) patrollers on here who can explain Inbounds Avalanche Danger to me.

This past Monday we skied Alta and Snowbird. Avalanche danger was rated “considerable’ for the Upper Cootnwoods backcountry. Most noted danger was windslab. It continued snowing and blowing very hard all day.

If I had been skiing in the backcountry, i would have avoided any terrain over 30 degrees, since windslabs were likely. I especially would have avoided any wind deposits I noticed.

But inbounds, although some terrain was closed, we skied more than a foot deep new snow, much of it wind deposited. Some of it steeper terrain.

Some terrain was marked “avalanche terrain, enter through gates only”. Other terrain was unmarked.
So how do I decide what terrain to ski or avoid inbounds? When is extra cation warranted? Do we consider that patrol checked this terrain(even the untracked stuff in the trees?) and considered it safe enough? Or am I expected to judge it for myself?




View attachment 64913 View attachment 64914

I was in a small avy inbounds on an open run a few years ago. PM for details and video.
 

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