Forums Avy Discussion Forum Snowpack strengthening or weakening? For feet and inches people
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  • #785727
    Scooby2
    595 Posts

    So with the exception of the formation of surface hoar or near surface faceting, generally a snowpack gains strength at gradients of less than 1 deg. C per 10cm in depth, we all know this. But I like this table because my weather stations report in Deg. F and I think in inches or even better in feet of snow (hopefully) on the ground. Looks like we are going to be in the sugar shack in the Wasatch out of the starting gate. Here’s to getting some feet down fast in your neighborhood!

    low in Deg. F…………………..Depth required to prevent facet growth
    ………………………………………….(not at surface of course)
    …………………………………………….inches / feet

    30……………………………………….4
    26………………………………………13 / 1 foot
    21………………………………………24 / 2 feet
    16………………………………………35 / 3 feet
    10………………………………………48 / 4 feet
    4……………………………………….61 / 5 feet
    -1……………………………………….71 / 6 feet

    #785744
    HansGLudwig
    601 Posts

    Cool way of sharing knowledge Scooby. Good to bookmark this.
    You have a snow thermometer in Fahrenheit and bring an inch ruler into the field?
    I just do all my snow science in SI units. That’s how the formulas are geared. It gets really cumbersome working with standard units.

    Be sure to bookmark Splitboard.com's Recent Activity page...
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    #785780
    Scooby2
    595 Posts

    When I did more pits and digging around, I’d force myself to think in metric. But what I do more of is count those cold nights and think about where there is x amount of feet on the ground as we move from a few feet of faceted snow to think about if the thicker snowpack areas on the shady sides are getting stronger again. It’s more like cringing when a week of real cold temps and no snow is forecasted and I know there is only a foot or two on the ground. It’s been so long since the wasatch started with a three to five foot snow cycle, maybe five to six years.

    Sorry to hear about your knee, hope you heal fast and 100%

    #785844
    SanFrantastico
    1514 Posts

    @scooby2 – that is really helpful for visualizing (roughly) whether facet formation is likely.

    But people should remember that the gradient will prolly not be uniform throughout the snowpack. Heat and water vapor will transport more and less readily through the different density layers of a complicated snowpack. That’s why observers will profile a pit’s temperature gradient from top to bottom with a thermometer. But keeping that caveat in mind your analysis is a really nice rule of thumb for us Americans, fuck yeah.

    Putting the poo in swimming pool since 1968.

    #785846
    Scooby2
    595 Posts

    Right SanFran, that is just how I think about it: is the overall snowpack likely to be strengthening or weakening.

    Like you said, you have layers that are more rich in vapor, faceting can focus above and below crusts, and day time temps will pump heat into the upper layers sometimes slowing faceting sometimes accelerating near surface faceting by driving heat gradients in both directions. It’s a rule of thumb that makes me think pessimistically about stability trends and steeper terrain before I even think about going somewhere on the shady slopes when there are slabs and not much snow depth.

    Next hope, a big dump to open up the best S and SW faces while our shady side snow grows weak.

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