Anthracites Playground 2-11-24

[MagnificentUnicorn]

I’ve skied the back up plan many times when stability and conditions are unfavorable. I’m of the mindset at my age that I really don’t want to die back country skiing. Terrain appropriate for the conditions, is the hazard manageable if you get caught by surprise with a slide? I ask myself these questions.


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[Foggy_Goggles]

And when considering a PWL such as depth hoar or buried surface hoar, are there any observations that you would rely on during your tour to make a stability assessment?

To me, this really is a challenge of backcountry skiing in on continental snowpack during winter. Upthread, we have talked about Red Flags. I'm not sure if that term is used as defined or in generality. None the less, Avalanche.org now recognized Persistent Slab as a Red Flag and note that the Local Forecast is now you know https://avalanche.org/avalanche-tuto...php#persistent

This is a pretty big change in curriculum and mindset to me.

[cravenmorhead]

I found it interesting that in his book (good book bad name, Art of Schralpanism) Jeremy Jones talks about treating any avalanche forecast mentioning a PWL as if it has a "high" danger rating, regardless of what the forecast center's danger rating is. His thesis is, and I'm paraphrasing, "I don't fuck with PWLs."

[adrenalated]

Avalanche.org now recognized Persistent Slab as a Red Flag and note that the Local Forecast is now you know https://avalanche.org/avalanche-tuto...php#persistent

Thanks for this, I didn't realize they had added this to red flags. I like it.

[Dantheman]

I don't like skiing sub 30 degree pow. I think it's boring as shit and I'd rather pick lint out of my belly button to be honest.

I wouldn't go as far as saying I'd rather pick lint from my belly button, but I understand the sentiment. It's so easy to get sucked into >35* terrain.

I’m of the mindset at my age that I really don’t want to die back country skiing.

Even more than the personally dying aspect, I really don't want to put my partner(s) and SAR folks through the trauma of recovering my body.

[snowaddict91]

Thanks to all that turned this thread into a good discussion on managing PWL. Will try to add some more thoughts when I'm at a PC and not on my phone but my line of thinking jives with a lot of the above conversation.

I'd love to say I avoid avalanche terrain anytime there is a PWL but that would be a lie as that leaves about two places I could ski and both are flat as a pancake. I ski there on certain days but couldn't spend my whole winter doing that.

Like GB I frequently turn to the lifts for my fix. Playing it smart would be a lot harder for me without that outlet.

[Lindahl]

I There's an old TAR where Billy basically suggests that Irwin is more Utah like than CO, given the snow that typically falls there. (It's at 330" for the year vs 200" in CB- pretty typical).

There's a few areas across Colorado that have insane orograohics, which is why I called out the Keblar pass region in my earlier comments about PWL bridging. I also rely on this as part of PWL management. On top of that I take advantage of significant local knowledge of the region I frequent, to avoid areas in the region that are shallower or are typically more faceted until later in the year. Like North, I give myself a pretty good margin when relying on bridging. Unfortunately, many in my region don't and we see recurring activity happen as a result which gets me super annoyed... if only they were a bit more patient we all could enjoy it - sometimes I mention that to them.

On particularly bad years or stretches, I do stick to lower angle terrain or manage it via low consequence slopes or skiing super fast across short stretches between obvious islands of safety. Regardless, it usually it sorts itself by March in my region (barring significant snowfalls, which can reactivate it). But we usually don't get super weak midpack PWLs like this year's SH. Thankfully it got super warm early this year which seems to have locked it down finally - based on my recent hasty pits.

And if luck rolls right, some years, we get such a strong Oct-Dec thaw, you can record, in your memory, slots that burn off, and if it stays persistently snowy, you can ski some really fun terrain early in the season. And then even better, some years we never get a prolonged period of cold clear nights and the depth hoar is super minimal and rounds/compacts pretty quickly. Those are the awesome years. I think 2012-2013 and 2018-2019 was like that for us? I can't recall exactly.

[Lindahl]

And when considering a PWL such as depth hoar or buried surface hoar, are there any observations that you would rely on during your tour to make a stability assessment?

To me, this really is a challenge of backcountry skiing in on continental snowpack during winter. Upthread, we have talked about Red Flags. I'm not sure if that term is used as defined or in generality. None the less, Avalanche.org now recognized Persistent Slab as a Red Flag and note that the Local Forecast is now you know https://avalanche.org/avalanche-tuto...php#persistent

This is a pretty big change in curriculum and mindset to me.

Other than snowpack depth by a combo of hasty deep pits in strategic areas alongside frequent visitation and significant local knowledge? No. Most Obs outside of those are useless for PWL management imo.

[Lindahl]

Even more than the personally dying aspect, I really don't want to put my partner(s) and SAR folks through the trauma of recovering my body.

Before I had kids, agreed. A buddy of mine has pulled two bodies out in one year and it really fucked with his head for a long time. It's easy to underestimate the impact an incident has to even those outside the triggering group, much less those intimately involved.

[bodywhomper]

Other than snowpack depth by a combo of hasty deep pits in strategic areas alongside frequent visitation and significant local knowledge? No. Most Obs outside of those are useless for PWL management imo.

Observed avalanches in similar (adjacent) terrain and aspect?

[Foggy_Goggles]

Observed avalanches in similar (adjacent) terrain and aspect?

Can be used to Red Light terrain but it's absence can not be relied upon to Green Light terrain due to both the Low Probability/High Consequence paradigm of PWL avalanches and the fact that generally speaking, this problem is not characterized by a natural cycle.

Thanks for that Lindahl, I'd agree that most of those strategies you brought up fall into the how to mitigate risk when dealing with a PWL. Without giving up your honey holes, are you talking about the CB/West Elks Area or somewhere else?

You did also touch on something that, for me, had become relevant in my local (Berthoud Pass) area. I'm a powder skier. I try and go a whole season in the backcountry which out crossing tracts. There are now way more skiers willing to take way more risk (my perception) under much higher danger ratings than me. Luckily for me/ I've transitioned from "Super Annoyed" to a level of acceptance. Rushing around trying to beat other groups to lines or adjusting your itinerary based on scarcity seems to be a dangerous game.

[Lindahl]

Observed avalanches in similar (adjacent) terrain and aspect?

Ah, yes, of course. My bad. But I know the history and current conditions of my specific region well enough that I rule out certain terrain before I even see evidence of other activity. So those obs don't really help me much. If I'm out there and use those obs to change plans, it's my belief that I've already made a seriously bad decision and use it as a big learning experience and work hard to figure out what I missed in my earlier analysis. So one could say that they aren't super useful in a general sense, but could save your life. Like Foggy said, these should be used to red light, never green light, due to spatial variability of PWLs. Absense of evidence is not evidence.

[Lindahl]

I'd agree that most of those strategies you brought up fall into the how to mitigate risk when dealing with a PWL. Without giving up your honey holes, are you talking about the CB/West Elks Area or somewhere else?

Somewhere else. I do know that the Keblar/Irwin area has similarly unusually heavy snowfall for Colorado though. As do a few other areas I don't really visit.

You did also touch on something that, for me, had become relevant in my local (Berthoud Pass) area. I'm a powder skier. I try and go a whole season in the backcountry which out crossing tracts. There are now way more skiers willing to take way more risk (my perception) under much higher danger ratings than me. Luckily for me/ I've transitioned from "Super Annoyed" to a level of acceptance. Rushing around trying to beat other groups to lines or adjusting your itinerary based on scarcity seems to be a dangerous game.

Yes, very much a dangerous game. I don't play it either. Luckily we've had visits drop off a bit on the less popular lines due to inconsequential incidents which has helped. However, it's mostly a close community, unlike Berthoud, so intercommunity chatter can affect behavior. Super annoyed is reserved for a few select behaviors, such as continually setting off slides in the DH layer throughout the season and ruining a set of lines until it warms up in March, by never letting it build up a strong midpack.

[Foggy_Goggles]

As because all generalizations are by definition false, here is a Forecast Ob detailing a natural avalanche cycle

https://avalanche.state.co.us/observ...7-1943e267b876

So tools in the tool box, information is powerful, look at the field reports from the entire state daily.

[Darren Jakal]

Lots of interesting academic discussion on the many aspects involved in an avalanche incident, but for anyone not well versed in these topics a simple take away might be:

1. Understanding and accurately assessing a PWL is incredibly difficult.

2. Terrain will play a huge role in the consequence of any avalanche.

3. Understanding and accurately assessing terrain is much easier.

[goldenboy]

Here's a graphic noted in today's CBAC forecast showing nearly twice as many slides in the lower snow SE zone vs the deeper NW zone in the past month:


And in the discussion:
"Our persistent slab problem is dictating today's avalanche danger and travel advice, and is more dangerous in the Southeast Mountains today. If you explore our persistent slab patterns since our prominent February 2nd weak layer was buried, you'll see that persistent slab activity in the snow belt (the Ruby Range) has been diminishing in the past two weeks, while activity has continued or even ramped up in shallower areas. The deeper snowpacks are gradually becoming more trustworthy, and there are now options in the Northwest Mountains to step out into more avalanche terrain with much less risk than earlier in February. Another good way to visualize this is by looking at accumulated snow water equivalent since our surface hoar layer was buried, which ranges from 9" at Lake Irwin, 7" at Schofield Pass, 5" at Gothic, and 3" on Mt. Crested Butte. All other things being equal, layers that have been buried under larger amounts of stress for longer periods are more resilient and harder to trigger. But of course, the potential size is larger."

---It's just one piece of info, but if we're adding to the deeper snowpacks discussion, there's something to read. For those of you not familiar with this area, Mt CB is about 8 miles from Irwin, with 1/3 the SWE in that discussion...

[muted reborn]

Lots of good info from everyone - thanks.

Warning: rambling and mansplaining coming up about why people ski what they do:

This is probably been thought of before, but yesterday I was thinking how often a skier's need to release a certain hormone into their body result in different terrain choices. I know that sounds funny and weird, ha, and I'm going into some big generalizations here, sorry not sorry.

Skiers similar to GB and Dan would prefer a healthy dose of adrenaline on most days not all days they ski - so going out to ski 25 degree slopes is not going to release any adrenaline, so why bother? The mental challenge of skiing a hard line is also a big motivation in what they ski. They easily can get their release in-bounds or out of bounds.

Other backcountry skiers prefer to seek endorphins - more of a zen peaceful experience where you don't have to plan out every turn to survive like on a run that ends in a cliff, and 25 degree slopes are super fun even if they'd prefer 35 degree tree skiing, if conditions allow. Some may even like eight-ing their partners turns, believe it or not! Ski areas with crowds, parking and tracked out lines does not release endorphins so they are out every day in the backcountry searching for peace.

Most of us often meet in the middle of adrenaline and endorphins regularly of course, it's not either/or every day you ski. But I see people's comments in this thread are coming from different hormone needs, ha.

Seeing where the avie happened I'd guess adrenaline was a key motivator for the young-ish ripping CB crew and heavily influenced all their decisions that day.

[MagnificentUnicorn]

I’m older, I’ll be 56 in two months. All of my adrenaline comes from skiing inbounds and a large part of endorphins do too but that’s because of my home hill and skiing solely midweek.

I’m fine skiing 30-35 degree pow in the backcountry during periods of elevated hazard, but I’m very particular about the slopes. I look for planar slopes that are well supported with little to no objective hazard. No cliffs mid run and little to no obstacles in the fall line of my chosen line.

As I’ve aged I’m happy just getting out there in the winter and not really worrying if I’ll make it home


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[Foggy_Goggles]

Muted and Unicorn...that's not stupid shit, that self awareness. Its a big part of the challenge of trying to stay safe. For better or worse and without judgement, the closer we push to the line, the more at risk we are. So be that age, risk tolerance, powder panic, social media, GoPro, getting in a fight with your wife or what ever, its a big part of the game.

[homemadesalsa]

Ok, so my thoughts on deeper snowpacks in a general sense. As mentioned above, at a certain point, they might be considered a bridge, and it's fair to just call that bridge a slab, too. I don't think it's just a CO thing. This year in particular, that entire west had pretty much the same dry spell in late Dec/ early Jan, and it resulted in a pretty similar snowpack (at least that's what I saw as someone who sometimes reads a lot of different forecasts). Utah provides a good example- a few weeks ago they were like "be careful, that layer on the ground is still there!" Two weeks ago, "that layer is dormant and extremely difficult to trigger". And now- nothing, not a mention of it. --Note, that's my paraphrase, not actual quotes.

So what happened? Is it just too hard to trigger now that it's a deep snowpack? Yes, but I'd also say that the same mechanisms that create DH can also create (or is allow the better word?) rounding in a deep snowpack. The vapor gradient (or temp gradient) no longer creates DH, but that nice warm blanket of snow can start to get that crap rounding.

I used the old phone a friend lifeline with a buddy who studied snow in college. Maybe he says it better. Note the last paragraph.
I'd love for some of you expert snow nerds to weigh in, I've always had a much better handle on snow turning into shit than the other way around..

"Mmm, yeah, lots of interesting stuff that goes on here. I'm going to use the term bonding vs healing, because we're talking about this framed with stability in mind.

I think its important to reiterate how facets and DH form, because the same process allows them to get stronger in the end as well.

Crystal metamorphism in snowpacks is driven by the vapor pressure gradient, high gradients mean high crystal growth. We can't measure vapor in the field, but temps actually follow it very close, so this is why we measure temps because we can see what the vapor gradient is doing. Ill use temp gradient moving forward, just know temp is tied to vapor transfer.

Okay so high crystal growth rates are found in large temp gradient and large spaces between crystals. This produces facets, which can develop striations and form large sized cup crystals, depth hoar.

On the other hand, low growth rates produce rounded forms, In alpine snow, low growth rates are usually low temp gradients and high ambient temps. Ground and air temps are close to each other. Less transfer.

So, at high growth rates we get faceted crystals, at low growth rates we get rounding. High growth rates imply high temp gradients, larger crystals and larger pore space with the highest growth rates occurring at high temps at the bottom of the snowpack. Low growth rate implies lower temp gradients (which imply higher ambient temps in the alpine) and small pore spaces.

Our persistence of instability comes from poor bonding with adjacent layers, lack of settlement and strength gain due to an anisotropic structure (angular structure), and cold snowpack temps.

Bond formation between layers and crystals occurs with increasing snow temperatures. So as we start warming up and rounding starts occurring, we see these facets lose their sharp edges and start packing closer together.

For the deeper snowpack, there's two things. First, settlement (associated with a strength increase) is slow in dh layers (and really any persistent layer) due to the angular structure. Weak in shear strength and resistant to vertical deformation (settlement). So it happens as it gets deeper, just slowly. Second, if we bury it really deep, the temp is way lower, so rounding happens."

Nicely articulated. I think of this stability assessment like the metaphor of the blind men trying to figure out an elephant [emoji208]. We use our mental models and science to make a 4-D map of the snowpack; tests and avalanche results (N and AS/ AM, etc) help us track it, but we never really know if we're feeling the ears or trunk or body of a sleeping elephant. Enough blind men submitting obs can build out our model picture, but we still need to acknowledge what we don't know.

Taking a PWL off the problem list is more a factor of its propagation propensity than its structure. Messaging and science have strong overlap, but not complete.

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[SILENCER]

I’m older, I’ll be 56 in two months. All of my adrenaline comes from skiing inbounds and a large part of endorphins do too but that’s because of my home hill and skiing solely midweek.

I’m fine skiing 30-35 degree pow in the backcountry during periods of elevated hazard, but I’m very particular about the slopes. I look for planar slopes that are well supported with little to no objective hazard. No cliffs mid run and little to no obstacles in the fall line of my chosen line.

As I’ve aged I’m happy just getting out there in the winter and not really worrying if I’ll make it home


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I'm a little younger than you, but your jam is basically my jam. Add two kids into it, and my conservatism dialed even further back. Like you, inbounds I'm 100% total crank. The steepest, stupidest stuff I can manage, esp with friends. Avy brain (largely) off, tips forward, laughing, cussing & a flask. Let's go.

B/C has morphed into the overall experience. The planning, objectives, exploration, fitness, solitude, adventure. I ski generally like a confident blue skier in the b/c. It's not even conscious...never was. It's still all about the "down" in the end. I'm still out there to ski. But it's less adrenaline in the b/c. While I'll flameout trying something hard inbounds (and laugh about it) for some reason the b/c...after alllll that effort to line up a perfect, safe day and find good snow on something cool, I'm less risky with the skiing itself and just soak it in. Yes, that def gets steeper in spring time, but for some reason just repeatable smooth "S's" and maybe the occasional pop off a rock here or there is more than enough. This is absolutely a happy balance for me. When I see the stuff many of my friends are skiing with higher risk tolerance than me early season, I get jealous...sure. But it doesn't last long. I want this to last forever.