Avalanche discussion thread

[sobo]

kinda like someone filming the incoming tsunami from the shoreline. Oh fuck

This!

 

Not a one of them looked like they were ready to boogie the moment the shit hit the fan. They were all just standing around gawking at the incoming "wave" and saying stuff like "Wow... holy shit..."

[ZimZam]

right up until the "oh fuck" moment. looks like they got tagged, although not severely. like you said, "lucky fucks"

[sean_beanntan]

Hmm I see discussion happening on the diff between considerable and high warning. So, I dig a pit if its high and not if its considerate? NOT!!!

Remember that they are not talking about your particular ski slope, nor are they talking about the conditions that are present at the moment that you are skiing the slope. If NWAC says considerable, I would dig a snow pit and do my own analysis. I always check the NWAC site but you cannot use that and nothing else. Skiing the BC means checking all available info and then owning your ski decision by performing your own tests. What's has happened to personal responsibility as regards determining slope stability?

Edited February 24, 2012 by sean_beanntan

[David_Parker]

A lot of intelligent posts here at CC.com and so kudos to all those sharing their views. Guess it's my turn...

 

This event has affected me deeply because it has once again demonstrated the false sense of security that comes with possessing the "required" equipment to travel in the backcountry. Mt. Guide's posts are excellent and brings to light all that really needs to be considered.

 

I have always maintained that accidents that lead to death are a tragedy. Tragedy's are almost always NOT a singular event, but rather a cavalcade of small errors in judgement. The Steven Pass accident imo demonstrates this. The avalanche itself was the defining moment, yet it could have and should have been avoided.

 

I was backcountry skiing at Stevens Pass that day. I have also skied exactly where they went that day. When I found out the details of when and where, all I thought was "what were they (not) thinking?"

 

I have sought and read as much of the online media versions of the accident and so much of the focus has been on the equipment and the fact they were "experienced". I read between the lines and there have been a couple good comments or quotes (paraphrased): "you can't wave your avalanche beacon at the slope and make it safe". "Whereas the focus of avalanche safety courses was originally all science, more and more the focus has shifted to the social aspect as well."

 

Beacons are for body recovery and you must always be objective in your decisions in choosing your ski routes.

 

Nowhere has anyone mentioned the number one piece of safety equipment we all carry with us: our brains. But like your transceiver, you must know how to use it.

 

I believe there were intense social pressures that day that caused brain malfunction. We had the director of Marketing at Steven Pass showing clients from Powder Magazine and ESPN a good time at his resort. In an effort to show them the really cool stuff to ski, they elected to ski the backcountry and headed to the Tunnel Creek Drainage. This becomes backcountry, not Sidecountry because unless you are all carrying skins, the only way out is down, no matter what conditions you run into. 25 feet down from the top, they were totally committed.

 

So here are my questions: 1. Did they check the NWAC report? (Considerable to high) 2. Were they carrying topo maps and thus aware the slope was 27 degrees or higher? 3.Did they consider carrying skins in case they encountered the conditions they should have expected to ensure a bail out option? 4. Were ALL the members in the group truly aware of where they were going and the risks, or were some following and trusting someone else?

 

I believe the Stevens Pass accident demonstrates the growing social aspects of side/back counrty skiing that puts pressure to ski where you shouldn't, that "experience" can lead to complacency and that your saftey equipment can help you, but won't save you from death.

 

I am truly saddened for the family and friends of those killed on Sunday. I hope their accident can serve to educate other skiers to make better choices and ski safely.

 

I never did give anybody hell. I just told the truth, and they thought it was hell.

Harry S. Truman

[JoshK]

I believe there were intense social pressures that day that caused brain malfunction. We had the director of Marketing at Steven Pass showing clients from Powder Magazine and ESPN a good time at his resort. In an effort to show them the really cool stuff to ski, they elected to ski the backcountry and headed to the Tunnel Creek Drainage.

 

I've heard this from several different people now, including another coworker who was skiing the Stevens BC that day. It certainly sounds like this event would not have happened if there weren't magazine reps along and pressure, explicit or not, to show them "the goods." That is sad, and while doubtful, I hope to see a future ESPN or Powder Mag article that fesses up to this and takes some credit for the social pressure the media/advertisers have added with their glorification of the extreme/steep n' deep/gnar/etc. More than likely that won't happen and the major headline will continue to be "avy airbag saved one life" that day.

 

I'm surprised those idiots from CO posted that video. Truly lucky call and what is more amazing is they were evidently too stupid to even realize that and instead chose to stand around shouting "woohoo!!" and continuing to film their sweet-ass video of their fellow mouthbreather.

[E-rock]

Lucky fukkerz...

 

Love the comments on the you-tube page from the guys who were in the near-victim party that think they didn't do anything wrong.

[kurthicks]

NWAC just posted their analysis for the Stevens accident for those of you interested in it.

 

http://www.nwac.us/media/uploads/documents/accidents/2011_2012/Preliminary_Tunnel_Creek_Avalanche_Accident_2-29-2012.pdf

[sobo]

Good, yet sobering, read, Kurt. Thanks for that.

[Mtguide]

Viewing/reading this NWAC analysis, I find it very interesting/ that the slide actually began at the top of the chute and at least partially in the trees, and from the color photo, evidently continued down through a very narrow chute, but still involving adjacent timbered terrain until the last open runout area. Here again the commonly accepted idea that staying in the trees is a good safety practice in avalanche-prone terrain, is very sadly and definitely disproved. There must have one hell of a snow-load on top of that weak bond of old surface hoar. The description at the beginning of the article certainly tells the story.

 

I'm wondering if, to help prevent ( I say "help" because, barring outright strictly enforced* closure of a given area, youll probably never completely prevent) such accidents in the future, the NWAC avy and weather forecasts and snowpack descriptions could be somehow either televised or displayed on monitors at the ski area where anyone thinking about entering the backcountry couldnt fail to see them. Maybe similar to the screens displaying flight schedules at the airport.

 

*(and Im not sure just how you'd do THAT, either)

[ScaredSilly]

I would not say that staying in trees will assure one of being safe. Sure it better than being on an open slope. And trees do act as anchors to help snow from moving. But once the snow is moving they force the snow around them - like a rock in a stream.

 

However, much depends on the density of the trees as well as the sliding surface. Ridge tops where the slide looks to have started are typically not that dense. I have been in what most would consider reasonably dense trees and had wet slides plow through. It was fricking scary as we could hear trees being knocked over.

 

Also remember that the slide could have propagated into the trees which could have done two things. One undermine the area where skiers were holed up thus forcing them from out from the protection of the trees. (i.e. the ground went out from under them). Second the moving snow could have engulfed them thus again forcing them from out from the protection of the trees. While ones body may be protected by a tree, their skis are certainly not unless they are behind a huge tree. Also remember, when one tucks behind a tree they are typically not right next to the trunk - either because of branches, tree well, or where they stopped.

 

Here is a good example of similar slide in Oootah in January that is very similar in multiple ways including a death.

http://utahavalanchecenter.org/accident_west_couloir_1282012

[obwan]

The sad part is - no one has all the answers on Avalanches, they are pretty unpredictable even though there are methods of prediction. But, as usual they are mother nature at it's very worse - such as floods, earthquakes or what ever. And the vote as to head for the trees or stay in the open is probably 50/50. It depends on the area - do you always have Cascade Cement coming down or some easy moving Snow Sugar. It's to bad the only cure is to avoid them when conditions start to add up - it's the old 3 strikes and your out. One mistake can get you by, and sometimes the second mistake will forgive you - but accidents (especially the ones I have had) are compounding; and when it adds up to three, your chances of surviving are slim. Be mindful of the powers of three.

Be Safe!

[j_b]

It looks like the terrain trap contributed in large part to the high body count. The slope that failed was quite limited in extent (200' wide) but the narrow chute insured that those caught were flushed all the way down the drainage.

[David_Parker]

Thanks for sharing the Utah report. I just spent over an hour reading other ones and I really like how they cover their accidents in depth. Very detailed analysis WE ALL CAN LEARN FROM!

 

I like this one as it talks about the social aspects...

http://utahavalanchecenter.org/accident_wall_voodoo_12142008

 

Spend some time reading these reports, they may help save your life!

[kerwinl]

I would not say that staying in trees will assure one of being safe. Sure it better than being on an open slope. And trees do act as anchors to help snow from moving. But once the snow is moving they force the snow around them - like a rock in a stream.

 

However, much depends on the density of the trees as well as the sliding surface. Ridge tops where the slide looks to have started are typically not that dense. I have been in what most would consider reasonably dense trees and had wet slides plow through. It was fricking scary as we could hear trees being knocked over.

 

Most sources on avalanche safety I have read or seen, indicate that trees must be spaced at less then 3 M or 10 feet from each other. That spacing is close enough to make skiing hard for a large amount of people.

 

I wonder how the increases in spacing effects the anchoring ability of the trees. I would be willing to bet the spacing vs anchoring ability relationship is not a linear correlation.

 

[tvashtarkatena]

The very existence of larger trees indicates some measure of protection from bigger slides. Trees also cut way down on wind deposition/crust and keep the snowpack shaded. Finally, tree bombs can do a decent job of avi control as conditions warm.

Edited February 29, 2012 by tvashtarkatena

[fern]

The very existence of larger trees indicates some measure of protection from bigger slides. Trees also cut way down on wind deposition/crust and keep the snowpack shaded. Finally, tree bombs can do a decent job of avi control as conditions warm.

 

 

This is such a dangerously wrong statement that I cannot let it sit.

 

The size of the tree next to you has ZERO relevance to whether or not the spot you are standing in is protected or exposed to slides either big or small. ZERO.

 

The AGE of the tree may have some slight relevance but you do not know the age unless you directly determine it by counting rings. When you count rings you will also find reaction wood growth from years when the tree was pounded over but not snapped. In locations where large slides knock out the canopy, new trees can grow very big very fast. Unless you count the rings YOU DON'T KNOW.

 

A "rule of thumb" for tree density above which snowpack stability might be assumed to be generally subcritical most of the time (note all the weasel words) is 10000 stems per hectare. The size of the stems is irrelevant. As someone noted, this works out to a tree density that is tight and tricky to ski through. These are not open glades.

 

Second - the effects of forest on the stability of the snowpack in immediate proximity (tree bombs, wind suppression) are also only relevant if the start zone of the avalanche is in the trees (happens, but not the most common). A more typical situation is a start zone in an open alpine or sub-alpine area that feeds into a path and runout zone in the trees. Once the slide is running the local stability of the snow within the forest is irrelevant. Bigger slides may not begin to decelerate until the slope is less than 20deg or even shallower, even with big trees.

 

Avalanche + Trees = Fatal Trauma. Don't fool yourself.

Past luck /= good judgement.

Hug-a-tree is for lost boy scouts in summer.

Choose your safe travel zones based on terrain not trees.

 

 

ref: course materials

http://www.avalanche.ca/caa/training/introduction-snow-avalanche-mapping

[Jim]

Thanks Fern, beat me to it. It's complicated. I've seen propogation and runnout in old growth - and seen some pretty big trees twisted into pretzels. Hoping to extend my bc skiing into '60s and '70s and thus very conservative. You only have to guess wrong once.

[Pete_H]

There is a real good discussion on this on TAY:

 

http://www.turns-all-year.com/skiing_snowboarding/trip_reports/index.php?topic=23262.0

 

Gary Brill had a pretty enlightening post:

I think the key is whether or not the "treed" slope is canopied or not. Canopied means you can see little sky. #2 photo is not canopied and hence surface hoar can form. Open treed areas are "great" for surface hoar formation and maintenance.

 

For a canopied forest, I have only a few times released a slab. This was on steeper areas of forest above 35-40 degrees. The slides were soft slabs (with snow falling heavily at the time) and because of the forest released over a limited area. Forested areas are more often than not bumpy which makes a slope less planar for slab formation.

 

Canopied forests: 1) act as a reservoir for falling snow and then subsequently drop that snow as a stabilizing influence, 2) anchor the snowpack in localized areas, 3) restrict windflow, meaning windslab is unlikely.

 

In general, I feel pretty safe skiing in "old growth" canopied forest in all but the most severe of avy cycles. I'm not exactly sure what a "hectare" is but I disagree that trees have to be nearly too tight to ski to provide safety.

[Pete_H]

Sure a gigantual avalanche originating in a large alpine cirque is going to take out some huge vegetation and whether or not you are "skiing in the trees" will matter little. However, most fatal slides are diminutive enough that trees will in fact provide shelter and will probably negate the start of a slab avalanche in the first place.

[pcg]

10,000 stems per hectare.

This is one tree per square meter - about as tight as can be managed and no fun.

 

The first pic in the TAY link above looks like Private Reserve up above Yoda Bowl at Mt. Hood Meadows and is about as tight as can be skiied and still have fun. I'm guessing it's about 3,000 stems per hectare? I never thought it could slide, but I'll be rethinking that, especially in areas of similar density that are steeper.

[JasonG]

I think the key is also if there is any sort of open slope above where things can get moving. I haven't ever seen avalanche carnage (busted or damaged timber)on slopes that were heavily treed all the way to the ridgeline. Also I think Gary and other's comments on TAY match my experience skiing trees on higher danger days. If the canopy is closed, and there aren't open areas, I haven't ever seen anything dangerous kick off, even during major avi cycles. Where there are openings, however, watch out.