Persistent Weak Layers and forecasting.

I have a good friend/IMGA guide/forecaster/rescue type person who been proposing that the forecasting community needs to change how they represent and convey PWL issues to the public for a few years now. His take is that a considerable rating due to a PWL is a lot different then considerable new snow issue. One is playing Russian roulette, the other could be possibly be navigated safely by a skilled party. (And several mags have brought this up recently) And the events of this season have show something is off.

Is it time to reevaluate the rating definitions and standards and make PWL issues it's own thing?
Like a 'no-go' color or PWL cross hatching for the rose? Something else?

I thought this was discussed online in like 2005/2006? If I remember correctly, part of the conversation was about having a new rating, “Moderate-X.” There was a healthy discussion about it on ttips, with many pros, including several from UAC, participating. What was the result of that discussion? Is it useful to move forward from that (and other) previous similar discussions?

I do not think a different way to convey the message about the type of hazard is a bad idea. I remember for a while the danger rose used to have “pockets” of higher hazard. Perhaps that style of addition information at the danger rose level can help convey the information and get readers to read the details of a forecast.

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Originally Posted by Redacted by user

It's a good idea and will likely help.

It's possible the Millcreek slide could have been mitigated if the backcountry skiing map had preferred skin routes as an overlay. The old man noted the skinner on that slope is supposed to go through the aspens to the right of the slide "based on prior lessons learned." The younger generations are eager to learn & I think would soak up that kind of knowledge if it were readily available.

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Oof. I kind of hate the idea of putting preferred skin tracks on a map. But maybe that's just a knee-jerk reaction on my part.

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I think it might be time to move away from consolidating the chance something will happen with the consequences of the outcome into one metric. This is already happening a bit with the advent of “spooky moderate & considerable”.

Ultimately I think we should use something similar to a JHA /HARC format (for BC skiing). That framework would likely help some skiers learn to conceptualize and internalize risk management.

I’m curious how other BC skier that have professional experience in fields with high safety standards and practices approach the risks of backcountry travel...so speak up or shoot me a pm

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Is it time to reevaluate the rating definitions and standards and make PWL issues it's own thing?

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Well, the current system has some holes that need a bit of work.

The issue is about route finding and safe travel, in other words, how to get around the mountains in winter.
Looking at the slide path in Wilson glade will reveal flagged trees all the way across the base with alleys from previous large slides cut out between the trees.
Haven't seen the monsters since early nineties? but avalanches run in 10-20-50-100 year cycles. Rather than focusing on danger ratings and filming video after video of digging snow pits for you tube, the focus should be on how in the hell you get around.
Don't need to spend half an hour digging when the hollow layer can be felt with a pole plant.
Terrain features can and do suggest safe paths on the up, which is where majority of the time is spent.

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Originally Posted by Bunion 2020

Well, the current system has some holes that need a bit of work.

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Agreed. How can we explain PWL in a visual manner that makes it easy for a casual BC user to understand how different it is than wet slides, wind slabs, or storm slabs? I know the simple answer here should be "education," but recent events with experienced users make me think we need to look deeper at a fundamental level.

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Originally Posted by snowaddict91

Agreed. How can we explain PWL in a visual manner that makes it easy for a casual BC user to understand how different it is than wet slides, wind slabs, or storm slabs? I know the simple answer here should be "education," but recent events with experienced users make me think we need to look deeper at a fundamental level.

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Not to be flip, but the audience for this information is the would be power users.

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Originally Posted by chickenNugget

Ultimately I think we should use something similar to a JHA /HARC format (for BC skiing). That framework would likely help some skiers learn to conceptualize and internalize risk management.

I’m curious how other BC skier that have professional experience in fields with high safety standards and practices approach the risks of backcountry travel...so speak up or shoot me a pm

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This is an interesting thought and one that’s crossed my mind on multiple occasions over the past couple weeks.

Also, there was an Avalanche Hour podcast with Chip Arenchild that mainly focused on risk management/mitigation in the workplace that I think would warrant a listen.

Have more to add to this later..

I think you start publishing risk matrices like shown in this google search as part of the avalanche forecast:

https://www.google.com/search?q=aval...-Cpx5hCjy2xTAM

None of it is new, but it's just not put in the actual forecast for everyone to see. Right now, it's left up to each individual user to even remember that type of risk-consequence matrix. Most probably don't visualize it. Of course, everything is left up to the individual, and the forecast center is not responsible for anyone's decisions.
From what's already out there, even an avalanche problem that falls on the very likely D3 size is still "moderate" or yellow hazard; for me, that's a total red zone.

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Originally Posted by wra

The issue is about route finding and safe travel, in other words, how to get around the mountains in winter.
Looking at the slide path in Wilson glade will reveal flagged trees all the way across the base with alleys from previous large slides cut out between the trees.
Haven't seen the monsters since early nineties? but avalanches run in 10-20-50-100 year cycles. Rather than focusing on danger ratings and filming video after video of digging snow pits for you tube, the focus should be on how in the hell you get around.
Don't need to spend half an hour digging when the hollow layer can be felt with a pole plant.
Terrain features can and do suggest safe paths on the up, which is where majority of the time is spent.

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This sounds like echos of the Jeremy Jones/ Krakauer session. So much good in that talk. I am going to watch it a second time. https://www.instagram.com/tv/CLDZsk9..._web_copy_link

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Originally Posted by snowaddict91

Agreed. How can we explain PWL in a visual manner that makes it easy for a casual BC user to understand how different it is than wet slides, wind slabs, or storm slabs? I know the simple answer here should be "education," but recent events with experienced users make me think we need to look deeper at a fundamental level.

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To explain it visually you have to show people video of it actually happening. This may sound funny but maybe one, of or some of the avalanche centers in conjunction with engineering colleges could have a contest similar to the south korean Skiing Robots Challenge. Have the robots simulate someone skinning and send them out under slopes in these circumstances. Not to mitigate but to educate. Everything could be recorded with sensors that detect surrounding slope angles, moment of collapse, depth of penetration at collapse, GPR or LIDAR, pretty much everything. Of course video too to show what happens to the human looking snobots in supposed safe zones.

It may sound funny (and the tuck is hilarious), but the technology is here. It was the first thing I thought of when I saw the video this morning.
https://www.youtube.com/watch?v=E-FAPKs1k-A

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Originally Posted by ryan14410

I think you start publishing risk matrices like shown in this google search as part of the avalanche forecast:

https://www.google.com/search?q=aval...-Cpx5hCjy2xTAM

None of it is new, but it's just not put in the actual forecast for everyone to see. Right now, it's left up to each individual user to even remember that type of risk-consequence matrix. Most probably don't visualize it. Of course, everything is left up to the individual, and the forecast center is not responsible for anyone's decisions.
From what's already out there, even an avalanche problem that falls on the very likely D3 size is still "moderate" or yellow hazard; for me, that's a total red zone.

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Where are you seeing an algorithm that results in a moderate danger rating for a very likely D3? If people really want to dig into how the danger ratings should be determined then you should search for and read the Conceptual Model of Avalanche Hazard.

Lots of good thoughts and ideas.

Now the curmudgeon in me comes out.

A large portion of the back country skiing population wants to be told if, "is it safe to go BC skiing today", never mind that the answer to that question will always be, "it depends".

They don't have the time or interest to deal with risk analysis or heuristics let alone reading the damned bulletins, just give them a danger rose and they have all the information they think they will need.

^Maybe don't make the danger rose/hazard rating accessible until you read the problems and previous (specified number of) days' obs.

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Originally Posted by powdork

^Maybe don't make the danger rose/hazard rating accessible until you read the problems and previous (specified number of) days' obs.

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My local forecasting center doesn't even publish a rose, narrative only. If you want to figure out the avalanche hazard you will need to spend more than 30 seconds looking at the report. This used to bug me, but after regularly checking UAC and CAIC and how buried the narrative is I think it's the right idea. Force people to read the narrative, not glance at a nifty graphic.

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Originally Posted by Bunion 2020

Lots of good thoughts and ideas.

Now the curmudgeon in me comes out.

A large portion of the back country skiing population wants to be told if, "is it safe to go BC skiing today", never mind that the answer to that question will always be, "it depends".

They don't have the time or interest to deal with risk analysis or heuristics let alone reading the damned bulletins, just give them a danger rose and they have all the information they think they will need.

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I'm pretty jaded at this point too, people are always finding new and exciting ways to screw up in the mountains. But that doesn't mean we shouldn't try.

I was reading about some of the successes and lessons learned about recent stop smoking campaigns.
An addictive habit that excites the brain but can kill you......and then there's smoking ;)

Criminalization and a "War" of some kind is clearly the answer here.

Whether there's a considerable or high danger doesn't equate to much difference in how to go about avoiding hazards. Instead of making the forecast more complicated, merging these two categories might convey a more straight forward, go/no go message. Then add the modifiers such as pwl, warming, terrain based manageability, etc.

This USAW presentation by Logan Cookler provides an example of how well a simplified system can work. They boil it all down to green vs. red runs for each days operations to avoid "runaways". Of course, they are bound to this as professionals, and there is continuity in knowledge of the terrain and avalanche history. All things in short supply these days amongst the growing mob of BC enthusiasts.

For dawn patrollers, the daily bulletins come too late in the day.

The Sierra avi center (Tahoe area) Instagram page includes the problem images in its IG posts. In that social media format, it takes one or two quick swipes for a user to see the images illustrating the types of problems, e.g., wind slab, storm slab, persistent slab.

An example of how Avalanche Canada presents PWLs (and other problems) in a separate tab. Recreationalists are taught to look at the ratings and the known avalanche problems as a minimum. Most years in the eastern Rockies PWLs exist as a listed avalanche problem for most of the season so it can lose a bit of meaning, but can be really useful for newer users as before you go out you're given the 1-3 avalanche problems to be on the lookout for. Then the chances and expected size gives you a quick understanding of the likelihood to consequence ratio.

Attachment 362257

I think adding skulls & crossbones to the rose might help in reaching people who can't be bothered to read the detailed forecast.

Seeing orange on there is obviously not a strong deterrent. A considerable likelihood of triggering a slide might not be seen as a big deal by some (I've expanded on this at length in another thread, considerable danger or wind slabs or new snow avalanches is something that can be seen as manageable under the right circumstances). Seing orange + skulls might remind people that the slides they can potentially get caught in are very high consequence ones that will most likely kill their asess.

Then again it would probably mean that people would treat orange without skulls as a greenlight...

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Originally Posted by powdork

To explain it visually you have to show people video of it actually happening. This may sound funny but maybe one, of or some of the avalanche centers in conjunction with engineering colleges could have a contest similar to the south korean Skiing Robots Challenge. Have the robots simulate someone skinning and send them out under slopes in these circumstances. Not to mitigate but to educate. Everything could be recorded with sensors that detect surrounding slope angles, moment of collapse, depth of penetration at collapse, GPR or LIDAR, pretty much everything. Of course video too to show what happens to the human looking snobots in supposed safe zones.

It may sound funny (and the tuck is hilarious), but the technology is here. It was the first thing I thought of when I saw the video this morning.

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Until you have them do it 10 times with no results, and then we've taught people it's not so bad?

I wasn't suggesting doing it live for people to watch. More of a slick M.A.D.D. type video. The triggering data i think would be interesting too.

But really I'm just trying to trick people into making a trail breaking bot.

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Originally Posted by Peyto

An example of how Avalanche Canada presents PWLs (and other problems) in a separate tab. Recreationalists are taught to look at the ratings and the known avalanche problems as a minimum. Most years in the eastern Rockies PWLs exist as a listed avalanche problem for most of the season so it can lose a bit of meaning, but can be really useful for newer users as before you go out you're given the 1-3 avalanche problems to be on the lookout for. Then the chances and expected size gives you a quick understanding of the likelihood to consequence ratio.

Attachment 362257

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"Most years in the eastern Rockies PWLs exist as a listed avalanche problem for most of the season so it can lose a bit of meaning"


I think this is a good point. When one issue shows up day in and day out at some point it will lose some impact for most users. I notice that UAC has been doing a good job of trying to write about the PWL differently day/week to day/week, and have started to even add zones on there that would be more likely to have this issue (i.e. zones with shallower packs). However, I do still think that when the exact same problem shows up on every report for 80 days straight people will start to minimize it (until an accident like wilson happens and it's the #1 focus now/again)

I've long said that the danger ratings are one of the least informative parts of the forecast- the good stuff is all in the problem types and forecast discussion. It always drives me nuts when someone says "it just went moderate!". Who cares if it's a pwl like we usually have in CO. Somehow they need to bring the problem types to the front, and put the rating in the back...

Great discussion and it would be interesting to get a psychologist's input on how people actually assess risk. I believe one reason PWLs are so dangerous is that humans are not adapted to rationally assess low probability/high consequence events like PWLs. I don't know if we will ever solve this problem but if we do lottery ticket sales will probably tank.

I don’t agree that the forecasting is the issue. Every forecast available is very clear about the issues in the snowpack, and those who read them and have the humility and discipline to adapt accordingly don’t have problems. However plenty of people either don’t read them, don’t think they apply to them, or just inexplicably act contrary to them. It’s fascinating to speculate about all the complicated psychological and societal factors at play in such risk taking, but imagining that changing how forecasts are communicated is somehow going address these fundamental human qualities, seems a tall order.

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Originally Posted by wra

The issue is about route finding and safe travel, in other words, how to get around the mountains in winter.
Looking at the slide path in Wilson glade will reveal flagged trees all the way across the base with alleys from previous large slides cut out between the trees.
Haven't seen the monsters since early nineties? but avalanches run in 10-20-50-100 year cycles. Rather than focusing on danger ratings and filming video after video of digging snow pits for you tube, the focus should be on how in the hell you get around.
Don't need to spend half an hour digging when the hollow layer can be felt with a pole plant.
Terrain features can and do suggest safe paths on the up, which is where majority of the time is spent.

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^^^
I've said that I don't know how to keep people on top of the snow.
That's not true. I've taught scores of people to do just that in and out of the ski area.
And paid great attention to linking up older with younger patrollers on routes.
How does one learn the stuff that a forecast can't teach you?
One learns it best from mentoring not just unguided experience.
So, how do we get young "expert" folks mentored?
Especially for the up where all time is spent and folks are most likely to be traveling through avy terrain more than one at a time, like wra says.
No one is gonna pay for it, and if it is free is it worth anything?

People have a hard time implementing the only highly effective strategy during shitty PWL = 0 avalanche terrain.

Recognizing avalanche terrain and skiing clear of it is more effective then any asterisk or X rating or whatever improvement on the forecast report.

IMO too many people want to make it about “making the call.” With PWL the call is not skiing on or under avalanche terrain until there is major bridging or a metamorphosis of some type.

Discipline is required. Days, weeks, months can go by without being able to ski on or under avalanche terrain. And that’s not as exciting as steep terrain today and requires constant attention from planning to skin track chatting to choosing the less exciting way down.










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Originally Posted by Kinnikinnick

People have a hard time implementing the only highly effective strategy during shitty PWL = 0 avalanche terrain.

Days, weeks, months can go by without being able to ski on or under avalanche terrain.

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The "or under" seems to be a major issue this year. A related challenge is that while PWL are pretty standard in some places, the "shitty PWL," as you called it, is a whole other animal. There are places I ski most winters on moderate days that I'm scared of this year.

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Originally Posted by Kinnikinnick

Discipline is required. Days, weeks, months can go by without being able to ski on or under avalanche terrain. And that’s not as exciting as steep terrain today and requires constant attention from planning to skin track chatting to choosing the less exciting way down.










Sent from my iPhone using TGR Forums

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This is the real crux of the biscuit. Discipline. I know Nancy Reagan ruined it for us, but truly, you gotta just say NO to avalanche terrain. Gotta be patient. Gotta wait til spring or til next year. Sure we could re-work the avalanche bulletin, but that's not the issue. People gotta OWN terrain choices. I know the general demographic that is getting smoked. As Pogo says, they are US, they are ME. Attachment 362316

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Originally Posted by total_immortal

Great discussion and it would be interesting to get a psychologist's input on how people actually assess risk. I believe one reason PWLs are so dangerous is that humans are not adapted to rationally assess low probability/high consequence events like PWLs. I don't know if we will ever solve this problem but if we do lottery ticket sales will probably tank.

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This, and then you add in familiarity.

I've talked a bit about this and decision making in general with my wife, who is a psychologist. She's not specialized in cognitive behaviour, so she's not really into these things, but overall she just says that most people are built so that they always try to justify why they can do something they want to do. As opposed to finding reasons not do it. The difference is mainly that different people relies on different heuristics.

I also work together with a few psychologist and other with degrees in psychology. Neither has really given me good explanations of how we function cognitively when we assess LPHC-situations. To me it seems that this "defect" has had a function in human evolution. Would you hunt wolly mammoths, if you considered the risk rationally? Or would you eat berries and whatnot?

I'm pretty certain that I on a group level see a difference between boys and girls in how they assess and accept risk. I'm pretty certain that there's been research into avalanches as well, were groups including girls are less prone to avalanches.

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Originally Posted by homemadesalsa

This is the real crux of the biscuit. Discipline. I know Nancy Reagan ruined it for us, but truly, you gotta just say NO to avalanche terrain. Gotta be patient. Gotta wait til spring or til next year. Sure we could re-work the avalanche bulletin, but that's not the issue. People gotta OWN terrain choices. I know the general demographic that is getting smoked. As Pogo says, they are US, they are ME. Attachment 362316

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There it is.

But an addict is going to do it regardless of the risks.
It's where we are

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Originally Posted by sfotex

I have a good friend/IMGA guide/forecaster/rescue type person who been proposing that the forecasting community needs to change how they represent and convey PWL issues to the public for a few years now. His take is that a considerable rating due to a PWL is a lot different then considerable new snow issue. One is playing Russian roulette, the other could be possibly be navigated safely by a skilled party. (And several mags have brought this up recently) And the events of this season have show something is off.

Is it time to reevaluate the rating definitions and standards and make PWL issues it's own thing?
Like a 'no-go' color or PWL cross hatching for the rose? Something else?

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To address the original post:
Where did the term pwl come from, anyhow?
A fancy term for what is usually large facets on the ground.
It's kind of a stupid phrase and like Sfotex says, doesn't have a warning bell to it.
There's a tremendous difference like he says between new and old snow avalanches.
We use to talk about "deep slab" or "full depth avalanches" instead of pwls.
That is we are talking about what could slide, not the weak layer that was the cause.
Much more attention getting, yes?
Always had an ominous ring to it, at least for me.
Maybe we should be talking about pwls less, and deep slab potential more, eh?

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Originally Posted by telefreewasatch

To address the original post:
Where did the term pwl come from, anyhow?
A fancy term for what is usually large facets on the ground.
It's kind of a stupid phrase and like Sfotex says, doesn't have a warning bell to it.
There's a tremendous difference like he says between new and old snow avalanches.
We use to talk about "deep slab" or "full depth avalanches" instead of pwls.
That is we are talking about what could slide, not the weak layer that was the cause.
Much more attention getting, yes?
Always had an ominous ring to it, at least for me.
Maybe we should be talking about pwls less, and deep slab potential more, eh?

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That is a good point. My first stint living in Colorado, we had a really bad year. I remember reading the term "deep slab" over and over in the report every day, seeing lots of reference and pictures of small slabs stepping down into the older snow and ripping out the entire bowl. I was scared enough, then I took a SAR page for a fatality. Third person down the slope iirc in a heavily skied area. Triggered a small slab that stepped down and wiped out the whole pitch. I don't think I left the resort for a month or two after that.

This is a really good discussion. I'm all about creative problem solving and I 100% agree that when the rating encompasses both probability and consequence, it has limitations with Deep slab/PSL/lingering problems with high spatial variability. That said, the true problem is consistently conservative decision making, a commitment to being awesome and being hyper situationally aware.

As a user group, we need to be more in tune with the fact that we are the problem. We talk about "heuristic traps" and "humans being inside the avalanche triangle" but it is not enough. I advocate for this being the number one and first agenda item for any day in the backcountry. Check in with yourself and be honest about how you are feeling, where your brain is at and make a commitment to safety. Do this before you even look at the forecast or start with any trip planning. Then have this conversation with your partners. Do it again as part of your beacon check. Have everyone look each other in the eye and make sure that you and your group respect each others lives to the extent that getting everyone home safely from now until forever is by far and away the priority.

If you can't do that or if you place something else above a true rigorous commitment to safety, you and your group are at risk and you may want to consider whether travel in avalanche terrain is an appropriate activity for you. Nobody wants to hear this. Everyone thinks that because they love skiing that the logical progression is into the backcountry.

In many ways it is the antithesis of ski area skiing which can be an escape from reality. Backcountry skiing can be the most stark and deadly teacher of reality.

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Originally Posted by Foggy_Goggles

This is a really good discussion. I'm all about creative problem solving and I 100% agree that when the rating encompasses both probability and consequence, it has limitations with Deep slab/PSL/lingering problems with high spatial variability. That said, the true problem is consistently conservative decision making, a commitment to being awesome and being hyper situationally aware.

As a user group, we need to be more in tune with the fact that we are the problem. We talk about "heuristic traps" and "humans being inside the avalanche triangle" but it is not enough. I advocate for this being the number one and first agenda item for any day in the backcountry. Check in with yourself and be honest about how you are feeling, where your brain is at and make a commitment to safety. Do this before you even look at the forecast or start with any trip planning. Then have this conversation with your partners. Do it again as part of your beacon check. Have everyone look each other in the eye and make sure that you and your group respect each others lives to the extent that getting everyone home safely from now until forever is by far and away the priority.

If you can't do that or if you place something else above a true rigorous commitment to safety, you and your group are at risk and you may want to consider whether travel in avalanche terrain is an appropriate activity for you. Nobody wants to hear this. Everyone thinks that because they love skiing that the logical progression is into the backcountry.

In many ways it is the antithesis of ski area skiing which can be an escape from reality. Backcountry skiing can be the most stark and deadly teacher of reality.

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^^^Good post.

Edited to add: Kin nailed it. You just have to stay out of avalanche terrain, up and down. If you can't accept the fun in that, then the resort is where you should stay.

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Originally Posted by Foggy_Goggles

In many ways it is the antithesis of ski area skiing which can be an escape from reality. Backcountry skiing can be the most stark and deadly teacher of reality.

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Man, so many people don't get this when they get their first BC setup. They are practically two different sports.

https://avalanche.state.co.us/foreca...e/front-range/

The hazard rating for today is MODERATE for all elevations. The associates verbiage is:

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Summary
You can trigger an avalanche large enough to bury you completely. The most dangerous slopes have firm slabs of recently wind-drifted snow. Identify and avoid steep areas with smooth, pillow-like drifts of snow. You're likely to find these under ridgelines and in steep, sheltered gullies. Avalanches can break into deeper layers and produce surprisingly large and destructive avalanches.

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In the first week of February, at least 14 people were killed in avalanches in the U.S., making it one of the deadliest weeks in 100 years. This comes despite advances in weather forecasting, personal safety equipment, education and training. There is no doubt that the mountains can be a perilous place. Still, safety is possible, but it requires nearly monastic focus and careful planning when conditions are dangerous. Even after all that, you have to stick to the plan and be ready with contingencies when the unexpected occurs.

Recent avalanche activity shows a pattern of larger avalanches recently and some running longer than expected. Despite low snow volume for this time of the season, bed surfaces are almost slippery, wind has concentrated snow in start zones, and avalanches are reaching areas that people haven't seen in recent memory.

Years like this are uncommon but not unheard of. Avalanches occur on a geologic timescale, with landscape-altering events occurring infrequently. It's a timescale more akin to massive floods than severe thunderstorms, as far as the frequency of severe events goes. Most people never see big avalanches in their lives. Others live through a historic avalanche cycle like March 2019 in Colorado.

This year, your previously used travel plans might not be safe. Long-running avalanches are always possible, but this year they are more likely. Keep your planning and communication tight and focused on careful travel and don't be afraid to adjust your plans if you get new information along the way.

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To me, as a 25+ year ski tourer in a Continental Snow Pack, my tour plan for today would be "AVOID ALL AVALANCHE TERRAIN". That doesn't make it the right answer, it just makes it my answer. The incidents this year are just reinforcing the idea that ski touring in avalanche terrain just sucks right now. Unless you are willing to avoid avalanche terrain, you are at risk. Go to the ski area, go meadow skipping, figure out a traverse, prospect new zones, get a snowmobile, learn to pow surf. Mid winter travel in avalanche terrain is the exception not the rule.