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  1. #51
    Join Date
    Dec 2008
    Quote Originally Posted by klar View Post
    I really appreciate all the input. This has been interesting, especially in contrast with discussions at home .
    Excellent thread.

    I agree that it's not possible to claim that climate change as such is the driver of the changes we have seen the last few years, but I'd say that in Norway the last few years have been very different from when I started skiing and freeskiing/touring as such became normal in Norway. The last 5-ish years have had more extreme weather; as in longer dry spells, bigger storms when they come, colder and warmer periods during the winter etc. This leads to more complex layering in the snow, more scarcity and bigger local variations. When this is added to the already somewhat funky geography of Norway, where you can go from a costal climate to a more "continental" climate within an hour, I'm surprised we haven't seen the same tendency as in the Alps regarding avy deaths.

    Quote Originally Posted by davidof View Post
    I was reading the German (swiss) article you posted in more detail and they seem to highlight problems with interpreting the bulletin when there was old snow situation (no fresh snow for some days) but one which involved a PWL.
    "Für die Benutzer des Lawinenbulletins ist es relativ schwierig zu merken, welche Situation gemeint ist"
    They suggest making the difference clear in the bulletin. We're assuming the user had gone beyond the headline risk which is frequently 2 in this situation.
    The bulletin is also trying to target two kinds of users: backcountry enthusiasts and people concerned with infrastructure, civil defense.
    Anyhow, the norwegian forecasting site has tried to put more information in the headline section this year.

    On the left it lists the regions with links to the region forecasts. It then lists the avalanche problems in the regions before the actual danger ratings (In the Indre Sogn region in actually lists a deep persistent weak layer). On some of the ratings you can see an exclamation mark suggestion that there is something specific to be aware of in addition to the normal hazards for a given rating.

  2. #52
    Join Date
    Aug 2006
    I like the concepts above ^^ that sf describes.

    Since the munter method is based on statistics, wouldn't statistics need to drive a change to the risk reduction methodology? are the statistics being updated with a goal of updating the method? (apologies if this has already been discussed upthread) Is there quality data from 2 more decades of touring and avi incidents in the sample region that could allow for a meaningful update? Some of the data may be skewed because of the use of the munter method during that timeframe, but I would think that could be accounted for in the number crunching.

    the very recent incident in japan with those kids (RIP ) made me wonder if there's a similar risk reduction tool in japan; however, i think it would have been mentioned here if that was the case.

  3. #53
    Join Date
    Mar 2017

  4. #54
    Join Date
    May 2007
    Quote Originally Posted by bodywhomper View Post
    made me wonder if there's a similar risk reduction tool in japan
    Nothing at all. Which is a shame as Japanese culture and character lends itself very well to rule based decision making.
    Life is not lift served.

  5. #55
    Join Date
    Dec 2014
    Colorado Front Range
    Quote Originally Posted by neck beard View Post
    Nothing at all. Which is a shame as Japanese culture and character lends itself very well to rule based decision making.
    That really is surprising! Thanks for starting this thread, klar.

    ... Thom
    Galibier Design
    crafting technology in service of music

  6. #56
    Join Date
    Oct 2003
    Quote Originally Posted by klar View Post
    uhhh. I don't think I understand what you mean. Bayesian problem as in a logical cause and effect issue? "Statistical" is perhaps the wrong word for the methods in question, maybe "empirical" would be better?

    If X% of skier triggered avalanches occur in steep slopes with a northerly aspect, avoiding steep slopes with a northerly aspect will decrease your chances of triggering an avalanche to Y%, compared to a chance of Z% (Z>Y) when you select a slope at random from slopes of all aspects and angles. What do you mean by historical rate in this context?

    Should the posterior distribution be reevaluated as more information becomes available (perhaps to incorporate additional "causal" variables), with the result then serving as the basis for a new model? yes.
    I mean the stats are not based on "selecting a slope at random", but they are applied that way. I was defining historical rate as incidents/# of tests, and we don't know the # of tests. For example it's likely there are more tests on northern exposures than southern exposures.

  7. #57
    Join Date
    Apr 2004
    Big slide in the Hautes-Alpes in France on Sunday, one ski tourer seriously injured, again due to the PWL that has been there since the start of the winter. The frontier area has been the scene of a number of big slides this season, such as this one in the Ecrins: - a "stable" snowpack that went on a PWL that was possibly reactivated with the spring weather - the area is in the shadow during the winter months.

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