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  1. #1
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    Sep 2006
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    Spring to summer snowpack transition

    There seems to be little information in literature and technical discussions out there on this and wanted to spark a discussion.

    Outside of the occasional snowstorm, managing instabilities after the snowpack has transitioned to spring is relatively easy. Just ski on a morning after a hard freeze as the surface is starting to transition to corn and you are good to go on just about anything you want. But what happens when we start to lose the freezes, as is happening in Colorado right now? Obviously, the first few days and (weeks?) of this condition require caution and conservative terrain selection to manage the risks of a wet slide or wet slab avalanche. However, how does one judge, when the snowpack has undergone a transition to a summer snowpack such that the freezes no longer are required to maintain stability on steep terrain? Clearly, shortly after losing the freezes when you are sinking up to your thighs, things may be unstable and clearly well into the summer when the snow is well consolidated and the surface is hard regardless of the temperature, the risk of a slide is low. My question is more related to the transition between those two extremes. How do you judge when you no longer need the freezes to get back onto steeper terrain? Does the old rule of thumb of "sinking into the snow past your boot-tops" just always apply or is there some other criteria commonly used?
    Last edited by skiracer88_00; 06-07-2022 at 12:23 PM.

  2. #2
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    Once the free water has thoroughly drained from the snowpack, I consider it transitioned to summer. Usually, even without a freeze, you won't find yourself sinking that deeply into a summer pack, except in thin areas around rocks. Even that can get surprisingly solid, too. My $.02

  3. #3
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    Bumping this one up again because it is an interesting topic to me this time of year.

    I thought it was interesting that the CAIC has dropped the "wet loose" problem from the avalanche forecast for southeast, south and southwest slopes. Since those aspects get the highest solar radiation throughout the course of each day, I imagine one could interpret as meaning that the snowpack on those aspects is more likely to be fully drained and has transitioned into more of a summer snowpack. Would this be a correct assumption? The CAIC does not discuss the reasoning for dropping the southern aspects from the report in the forecast discussion, but that is my assumption.

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  4. #4
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    See, this is another failure of the CAIC. I can say with 100% certainty that the CBAC would say something like "We've decided to drop wet/loose concerns on SE through SW aspects because of ____". CAIC rarely gives any explanation even though that's exactly what the forecast discussion should be for.

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