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  1. #1
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    Understanding snow pit data

    Anybody have any links (or feel like playing teacher) on how to read these charts?



    Searching around for 'snow pit data' isn't too productive.


    Thanks!
    Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp

  2. #2
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    im going to guess here
    temp gradient is at the top and represented by the line
    snow hardness is at the bottom, knife, pencil, 1finger, etc, and represented by the blue bars
    on the right is the snow depth. the symbols are the standard sybols for snow grain type along with their size...i can dig this up somewhere if you need.

  3. #3
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    Yeah I recognize some of it. I was just wondering if there was a comprehensive description of any and all possible data somewhere.

    You know.....if you feel like it


    I'm looking around with google right now. If I find something, I'll put it up.
    Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp

  4. #4
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    some Snow crystal symbols
    http://www.atmos.washington.edu/~sto...l_symbols.html
    a couple books at home have the full list\more common ones

    symbols and abbv's
    http://www.avalanche.org/~research/g.../AppendixI.pdf

    Kidwoo
    Section 2.5
    everything you want to know
    http://www.avalanche.org/~research/g...f/Chapter2.pdf

    got those from here
    http://www.avalanche.org/~research/guidelines/
    Last edited by pechelman; 02-19-2009 at 10:40 AM.

  5. #5
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    Understanding snow pit data is more advanced and is typically reserved for the AST 2 courses. But....the data above shows the following:

    Red line (zig zag) is the temp gradient through the snow pack. The Depth is indicated in cm on the right.

    Blue Bars - indicated snow hardness through the different layers. Also indicate overal depth of each layer.

    Far right - shows the compression test results (easy, medium hard), the shear quality (Q1, Q2, Q3), the score (number of taps), and depth of the shear.


    Symbols - standard symbols indicating crystal type and size (facets, depth hoar, surface hoar etc.)

    Not sure what else you would like to know?

  6. #6
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    Right on.

    Just found this while pechy was linking to it.

    http://www.avalanche.org/~research/g...f/Chapter2.pdf


    I just want to be able to look at those reports and understand them somewhat efficiently.

    Thanks guys.
    Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp

  7. #7
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    Dumb Swede has a lot of this right on. The first thing you would want to understand is whether this pit was from top to bottom or bottom to top. Typically if you are not digging to the ground the pit would represent top to bottom.

    Column one from left to right show the following:
    1. Temperature in Celcius represented by the red line. Temperature numbers are at the top of the graph.
    2 Each of the blue rows in column one represents layers and the respected density in each layer. At the bottom of the graph you will see the hardness scale of F (fist) 4F (four fingers) 1F (1 finger) P (pencil) K (knief).
    3. Often you will see the crust layers in this area as well represented as solid black lines

    Column two show the height of the snow pack in CM. In this case the pit was dug to 180cm. Look at the notes at the top to see if it was dug to the ground. This information was not entered in this pit diagram and you should assume this was dug to the ground with the top being the top of the snowpack.

    Column three shows the crystal form symbols. These symbols and their meaning can be found in pechelman's post. What is important here is the crystal forms above and below temperature gradiants (i.e. +1.0 degree celcius change in 10cm). In addition you want to look at the crystal forms above and below the failures found in the stability test column

    Column four shows the size of the grains in mm for each layer.

    Column five typically shows the density of the snow similar to column one. In this pit the information was not entered.

    Column six shows the failures and the stability test performed. In this case from top to bottom you have 2x CTM Q2 Depth: (cm) 160 CT score 20 (Translation) Compression test was performed with a medium score of 20 from the elbow. The quality of the shear for this failure was a Q2 (ragged). It failed at a depth of 160cm. This tested was repeated twice with the same results.

    Second failure occured at 93cm as shown in the CTH Q3 Depth: (cm)93 CT score 29. Translation: This was a compression test with a score of 29 from over the head with a very ragged Q3 shear at 93 cm from the bottom. This result occured only once.

    At the very bottom of the stability test column shows the ECTNR. Translation: An Extended column test was performed and it rendered no results with no probagation.

    Understanding these results as well as being able to create these pit diagrams is typically handled in a Level II avi course. Keep in mind this only represents the snow within this area or location and does not represent the entire snowpack at all elevations or aspects. Where the pit was dup will also have a bearing on the results.

    Snow pits should only be one of the tools used in your overall decision making process and should probably be one of the last pieces of info you use in your tool bag. I typically tell my students that they should pretty much know what kind of results they are going to get and what snow they will be seeing in their pits before they dig them. You will occationaly get surprises and this should factor into your decion making process. Sorry for my preaching in this subject. I hope this helped. PM me if you have any specific questions.

    Profile Key: http://patrol.mammothmountain.com/Pr...ProfileKey.jpg

    Crown Profile with pictures
    http://patrol.mammothmountain.com/Pr...xWaterfall.jpg

    Crown Profile Pit - Notice this is from Top down to bed surface. In this case the top of the snowpack is represented at 0cm

  8. #8
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    ^ I like that mammoth report with the grain key on the left. That's actually mostly what I was looking for. I've been bc skiing and digging pits for years and took an avy 1 class years ago, but just never used these reports as a resource. These guys are doing them so I just want to be able to know what they're conveying.

    Thanks for all the info.
    Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp

  9. #9
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    Kidwoo,

    The software to publish the pit diagrams is free and can be found on the patrol.mammothmountain.com web site. I believe this is the link. I agree using these pits are a great resource. The can give some clues as to what has been going on with the snow pack and what you should be looking for within a given area. The info from the Sierra Avalanche center is great and I go there often to look at the pits dug recently.

    http://www.snowpilot.org/

    Hope this helps.

  10. #10
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    Folks.....I know all you know this as experienced BC people but I want to point this out should someone stumble on this thread. Snow pit analysis is not as simple as it appears. It requires a shit load of experience in order to accurately interprit the data. Understanding what everthing stands for on the chart above is not enough. This is serious stuff and frankly, avanlanche forecasting is an art, not a science.

  11. #11
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    Quote Originally Posted by srface_hoar View Post
    Bumping because I was looking for ^ & the link is broken. After a bit of looking, came across Comprehensive Canadian Craftsmanship guide here: https://cdn.ymaws.com/www.avalanchea...GRS2014web.pdf

    It's a long read, but as Swede pointed out, if you are reading someone else's observations online in an attempt to get a handle on local snowpack, you probably want to try to understand a lot of the nuances... Knowing the difference betwn a 5 and a 15 on a CT for example is a common mistake seen even in some otherwise pretty decent media out there

    However, if someone can find and wants to bump the link to the short version like what used to be in this thread, that would be appreciated.
    "In the end, these things matter most: how well did you love? How fully did you live? How deeply did you let go?" - Buddha

    "Come back alive, come back as friends, get to the top-in that order." -Mark Twight

  12. #12
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    Quote Originally Posted by kidwoo View Post
    Right on.

    Just found this while pechy was linking to it.

    http://www.avalanche.org/~research/g...f/Chapter2.pdf


    I just want to be able to look at those reports and understand them somewhat efficiently.

    Thanks guys.
    Link is broken.

  13. #13
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    The Snow, Weather, and Avalanche Guidelines (SWAG) handbook is online here: https://www.americanavalancheassociation.org/swag/

    It's pretty comprehensive.

  14. #14
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    Quote Originally Posted by Dumb Swede View Post
    Folks.....I know all you know this as experienced BC people but I want to point this out should someone stumble on this thread. Snow pit analysis is not as simple as it appears. It requires a shit load of experience in order to accurately interprit the data. Understanding what everthing stands for on the chart above is not enough. This is serious stuff and frankly, avanlanche forecasting is an art, not a science.
    i took a semester long snow science course that was way better bang for my buck as avvy 2 and help me be my own forecaster
    ill look into the avalaunche forecasting artist class
    "When the child was a child it waited patiently for the first snow and it still does"- Van "The Man" Morrison
    "I find I have already had my reward, in the doing of the thing" - Buzz Holmstrom
    "THIS IS WHAT WE DO"-AML -
    ski on in eternal peace

  15. #15
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    Quote Originally Posted by maximusj View Post
    The Snow, Weather, and Avalanche Guidelines (SWAG) handbook is online here: https://www.americanavalancheassociation.org/swag/

    It's pretty comprehensive.
    If you want a physical copy you can buy it off the A3 website. www.americanavalancheassociation.org
    "True love is much easier to find with a helicopter"

  16. #16
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    ^which you should so they keep offering hard copies.

  17. #17
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    Quote Originally Posted by hafjell View Post
    Link is broken.
    Hard to imagine a link from 10 years ago might not still be valid.
    Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp

  18. #18
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    Quote Originally Posted by NWFlow View Post
    ^which you should so they keep offering hard copies.
    Mine just arrived. It's excellent.

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