Timely Avi Danger Reminder - Mt Bogong

Discussion in 'Backcountry' started by Hully, Jul 12, 2017.

  1. sbm

    sbm Dedicated Member
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    I got home and pulled the Bible off the shelf (aka Bruce Tremper Staying Alive in Avalanche Terrain) and already found of a couple of great tidbits.

    Firstly he also states that wind grinds up the snowflakes, so they pack into a denser layer than snow falling in calm conditions.

    "Wind usually starts drifting snow at around 15 km/h, and most of the real action happens between about 25 to 80km/h. Wind faster than 80 km/h actually blows less snow around because, at least in dry conditions, it tends to blow the snow into big plumes that jet off the ridge tops, and most of the snow evaporates before it ever reaches the ground again. The snow that does make it back to the ground tends to be not only far, far away but also spread out more evenly instead of in discrete drifts. So just like slope steepness, it's the intermediate values that cause the problems"

    "More time [of strong winds] equals more transport - but once again, only up to a point. Most of the damage usually comes in the first couple of hours of the windstorm. Once all the light fluffy snow gets blown around, then the wind has to work harder to blow the rest of it"

    "Most avalanche fractures occur within a distinct weak layer sandwiched between two harder layers, but sometimes the fracture occurs simply because of a poor bond between two layers - in other words, a weak interface. For instance, a hard slab might slide directly on a hard rain crust with no distinct weak layer involved" - note this describes the avalanche that started this thead, and that it's a footnote compared to the time dedicated to many other weak layers like depth hoar and faceted snow - weak layers which we just don't get.
     
  2. skifree

    skifree Part of the Furniture
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    Food for thought there.
     
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  3. Endless_Winter

    Endless_Winter Dedicated Member

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    I was a little surprised too, but remember in the right conditions, they say up to 10X the amount of falling snow gets deposited under medium winds, so all you need is the small dumps we have been getting + wind (which we always get) and there you have it. Go up in summer and there'll be the last wind lips on those 1st three runs (tombstone, death cookie and bermuda) still there easily into early december.

    Whilst the crown photos make this avalanche look massive, it's actually way smaller than it looks (it's really a cornice fall then whatever smallish amount of loose dry snow on the slopes below avalanching. I'm not trying to downplay the risk, just that the size of the crown makes it look a little meaner than it probably was.
     
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  4. crackson

    crackson Addicted Member
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    Why can't we have howitzers and grenades in oz?
     
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  5. Rabid K9

    Rabid K9 Dedicated Member
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    I do as a matter of habit, but my snow time in Oz compared to overseas is about 1%.

    Of all the places not to wear a beacon. The days I've ventured backcountry in NZ without some kind of slide / geotechnical incident taking place are virtually non-existent. Pound for pound, I think there's not to many more dangerous mountains.
     
  6. Boodwah

    Boodwah Dedicated Member
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    Never use beacon in Oz, I'm frequently solo anyway. I just choose safe lines in safe conditions on bluebird days! I just like nice casual days of heavy exercise, and mostly just cross my fingers that nothing totally unpredictable occurs. The spring corn in Oz is usually safe as houses. By the time you need to venture further afield to find freshies in Hotham, the snow has usually consolidated anyway. As my kids start to venture BC, I'll probably take some beacons out just for games.
     
  7. CarveMan

    CarveMan aussieskier.com
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    Given that I mainly tour in spring, that's pretty much my thoughts.
     
  8. Red_switch

    Red_switch Part of the Furniture
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    Most avalanche deaths in NZ occur in summer. Slightly different I know, but the thing is, people tend to be killed in avalanches when they least expect it.
     
  9. CarveMan

    CarveMan aussieskier.com
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    I read a quote the other day that could be applied to avalanche danger. It went something along the lines of "it's like winning the lottery, you could play every day of your life and never win, and then there's the guy that enters once and gets the jackpot". I feel it's very applicable, as you don't necessarily get instant feedback in avalanche terrain for doing the wrong thing, and in fact you could do the wrong thing a lot and get away with it, however conversely you could also get immediate feedback for doing the wrong thing...
     
  10. Telemark Phat

    Telemark Phat Part of the Furniture
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    Valid point about avalanches often happening when least expected (Kunama), but the South Island and Australia aren't comparable, either by topography or snowpack. Someone please correct me but I'm not aware of a single avalanche death in Oz in Spring, let alone in Summer. I can't think of more than 10 Avalanche victims in Australia. There have been plenty more who have died to exposure, poor navigation of slipped on icey slopes.
     
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  11. Boodwah

    Boodwah Dedicated Member
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    I got caught in a big spring one in Avalanche Gully off Feather one year, could have ended very badly. Fresh fall of v late september snow on old red-dusted snowpack, all slid in midday sun after I triggered it. Kind of a unique Oz spring phenomenon.
     
  12. crackson

    crackson Addicted Member
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    Weak layer of mud?

    DING, DING,DING,DING.
     
  13. crackson

    crackson Addicted Member
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    I have heard stories of monster slides on western faces in spring.
     
  14. telecrag

    telecrag Part of the Furniture
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    Lady Northcotes.
     
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  15. Red_switch

    Red_switch Part of the Furniture
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    Two guts died last year on low terrain in a wet snowpack.
     
  16. chokenchickin

    chokenchickin Active Member

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    About 15 years ago in mid September, I saw enough debris to bury a bus in Cairn Creek from the very same gully that slid on Bogong this week. A few days before that I had a near miss in the Escarpment Chutes area. A few years after that a mate in my group got buried up to his neck in Craig's Slide. Very humbling realizing that luck has played a greater role than skill in these instances.
     
  17. snowgum

    snowgum Dedicated Member

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    Can anyone advise roughly want a beacon costs in oz? And perhaps outlets that stick them? If any?

    These items arent cheap / theywere expensive in European stoes in mid 90s.

    Can one hire / perhaps Jindabyne?
     
  18. AndrewA

    AndrewA Well-Known Member

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    I remember some huge chunks of stuff in Cairn Gully about 8-10 yrs ago - they originated from the cornice at the top in line with the summit. But they were car sized, and came right down into the bottom of Cairn Gully.

    A
     
  19. CarveMan

    CarveMan aussieskier.com
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    I sell beacons, this is the least expensive but still very capable: https://aussieskier.com/products/bca-tracker-2-avalanche-beacon
     
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  20. climberman

    climberman CloudRide1000 Legend
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    I have a pic somewhere borrowed from this forum of the S entrance to the Sentinel ripped to dirt / shrubbery in a spring full depth avalanche. Year 2000 I think.
     
  21. jonathanc

    jonathanc Well-Known Member

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    Would like to see that from a safe distance... e.g. top of carruthers.
     
  22. Endless_Winter

    Endless_Winter Dedicated Member

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    Glad you're OK from the recent bogong incident. Who am I going to ride and talk Furanodake with, skinning heavenly when this years mid October storm hits???? :p:p:D:D



    -----------------------------
    My following thoughts are not directed at anyone, merely some idle thoughts and my boring 2c worth.

    I've thought a lot about mitigating risk riding Bogong (amongst other places). I usually ride up there alone which means I really have to think hard about the conditions, gear and plan A,B,C,D, what if, what if etc etc. The good thing is that it has multiple aspects to choose from so on any given day or time of day it's actually not hard to find some nice, well safe, riding during higher risk days (provided vis/weather is not an issue).

    A good understanding of the type of mountain foe you're dealing with is essential. You can build up some expectations prior to departing by looking at the weather in the week (well indeed the whole season) prior - wind direction, precipitation amounts and type are a good start. I have no idea who these guys are but, http://mountainsportscollective.com/index will give you a good idea of what is happening in the alpine. The hotham report (I haven't looked at other resorts) also gives a short BC précis. On a scale from "fluffy kitten" to lion from 'ghost in the darkness', what are we looking at mountain-wise today? When you do get up in the hills, gather as much information as you can, by looking (is there any natural activity? is there any skier triggered activity? Where is the wind blown snow? is the snowpack wet or dry?) and digging (confirming what you have read or hypothesised, bearing in mind a snow pit 10m from where you are currently digging may yield totally different results) and talking to people (ski patrollers usually like ski touring and often give invaluable info). You are seeking to confirm or change the expectation you have built up.

    Is the problem you are dealing with related to the time of day (i.e. wet snow in spring on steep solar aspect)? Is it a temporary issue that is going to cure itself over a relatively short time frame i.e. days (snowpack adjusting to the weight of storm snow)? Is it a longer term issue such as a weak layer of frost underneath 50cm of fresh snow? Is it rain on fresh snow (ALARM KLAXONS)? Does it vary with aspect and elevation (e.g. wind slab)? How does the terrain hinder (gullies, trees, rocks in the fall line below) or help me (chute widening out to mellow terrain) with any or all of these problems? What are the terrain options? Is there gear I can take that will mitigate any of this or am I giving my self a false sense of security by carrying them? Do I need ski crampons (if it's Australia then the answer to this question is YES btw)? Is the problem even avalanche related (weather in alpine, slide for life, rocks, getting cliffed out, exposure etc)? Don't let all your decisions be driven by where the good snow is. If I suddenly find myself unable to walk right now, can I contact the cavalry and can a helicopter/sled/alpine rescue/whatever get to me right now and in what time frame? Can I survive the night here? It's so easy to get fixated on avalanche problems and forget about all the other stuff.

    Most importantly, how can I change my plans to minimise the likelihood of any or all of things killing or injuring me and my crew and yet still find some good snow?


    Here's my take on Bogong:

    If you're dealing with a 'winter' avalanche problem up on Bogong, let's face it, it's gonna be windslab - then you're often better off "seeing and avoiding" rather than "searching and destroying". The problem is that most people inevitably head straight to the glory runs starting at tombstone then curving around. These happen to be the high risk areas for windslab. Why not start with a mellow run down the west facing side of the gully? This gives you a great look at these east faces (photo time) and you can establish whether there's been any natural activity. I don't like being the first one down a run in avalanche terrain after a storm, so you might also see other people's tracks and if there's been any sluffing and/or skier triggered events. This beats peering over the (convex!) wind lip looking at each other and wondering if you should drop in. At the bottom of your first run you can even cross the creek and get out your shovel and have a dig, although that's not going to tell you a lot about the slab at the top. You can even ride the N mellow side of the east faces at the top of cairn gully (and have a dig at the top) and if you are feeling the love then head on up for tombstone et al. If you do decide to ride these runs then make sure that ONLY 1 PERSON is exposed to any one risk at any one time. At least if it does go, you've mitigated the consequences. I usually come out at the bottom with a head of steam and head left to a safe spot, possibly crossing the creek (if it's safe). Last thing you want is your buddy to trigger a slide and you're in the fall line.

    And remember no much how much you know and how much experience you have - avalanche risk is more quantum physics, that is probabilities, rather than newtonian mechanics, which is certainty.


    Sorry for the dribble.
     
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  23. SkiMountaineer

    SkiMountaineer Active Member

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    I'd also add that you should never forget that you can also trigger an avy from the bottom of the run, so take care when checking out a slope from below. Also, make sure the first person exposed to a risk is in a safe place before the second person exposes themselves to it (eg. crossing risky terrain, not just riding it).
     
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  24. Endless_Winter

    Endless_Winter Dedicated Member

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    Yep, the mountain does not care whether you are going up it or coming down it!