Snow Pits

[Carl_Healy]

Two questions for everyone here.

First, how often when hiking/climbing in winter do you dig snow pits to gauge the state of the snow pack?
I can't seem to ever find any mention of people doing this in winter peak condition reports or trip reports, unless I just have been looking at the wrong reports.
Or is it a case of "If your route takes you through terrain where you need to verify the stability of the snowpack with a pit, then it's probably a route that should be avoided to begin with?"

Second, during my AIARE 1 course two weeks ago my instructor made it seem that it's common courtesy to fill in a pit after you've examined it. I can understand the reasoning behind this if the pit is dug in a location where it can pose a hazard to an unsuspecting skier uphill. But otherwise if the pit is well located and visible, wouldn't it be more helpful to others touring in the back-country to leave the pit open so they can see the state of the snowpack more easily?

[CaptainSuburbia]

Or is it a case of "If your route takes you through terrain where you need to verify the stability of the snowpack with a pit, then it's probably a route that should be avoided to begin with?"

This for me

[NathanRL]

Second, during my AIARE 1 course two weeks ago my instructor made it seem that it's common courtesy to fill in a pit after you've examined it. I can understand the reasoning behind this if the pit is dug in a location where it can pose a hazard to an unsuspecting skier uphill. But otherwise if the pit is well located and visible, wouldn't it be more helpful to others touring in the back-country to leave the pit open so they can see the state of the snowpack more easily?

The existence of the pit is gonna affect the snow (temperature, wind exposure, etc.) But if anything that seems like an argument for leaving it open, so that people don't accidentally dig into your filled in pit and think "wow, I can't make out the layers at all!" (Very small chance of that, I suppose.)

[Dave B]

First, how often when hiking/climbing in winter do you dig snow pits to gauge the state of the snow pack?
I can't seem to ever find any mention of people doing this in winter peak condition reports or trip reports, unless I just have been looking at the wrong reports.
Or is it a case of "If your route takes you through terrain where you need to verify the stability of the snowpack with a pit, then it's probably a route that should be avoided to begin with?"

Very rarely, CO snowpack is far to spatially heterogeneous to put much weight in snow pits unless you're doing many of them on a variety of aspects, elevations, and load zones. The Avaluator is a quantitative approach to overall terrain assessment and allows you to make go/no-go decisions based on simple observations and risk tolerance or confidence in buddies ability to find you and dig you out.

Second, during my AIARE 1 course two weeks ago my instructor made it seem that it's common courtesy to fill in a pit after you've examined it. I can understand the reasoning behind this if the pit is dug in a location where it can pose a hazard to an unsuspecting skier uphill. But otherwise if the pit is well located and visible, wouldn't it be more helpful to others touring in the back-country to leave the pit open so they can see the state of the snowpack more easily?

Yeah, you need to backfill a snow pit. If you do an ECT in it, it'll be useless for anyone else. Not to mention that exposing an otherwise buried surface with affect pack structure and lead to even more biased results than a CO snow pit would normally give.

[Carl_Healy]

Second, during my AIARE 1 course two weeks ago my instructor made it seem that it's common courtesy to fill in a pit after you've examined it. I can understand the reasoning behind this if the pit is dug in a location where it can pose a hazard to an unsuspecting skier uphill. But otherwise if the pit is well located and visible, wouldn't it be more helpful to others touring in the back-country to leave the pit open so they can see the state of the snowpack more easily?

Yeah, you need to backfill a snow pit. If you do an ECT in it, it'll be useless for anyone else. Not to mention that exposing an otherwise buried surface with affect pack structure and lead to even more biased results than a CO snow pit would normally give.

Yeah I was more thinking about someone coming across a pit no more than a couple hours later, particularly if it's not windy and the pit doesn't have direct sun exposure. Obviously if it's a windy day or someone comes a across a pit more than a day or so later then I can imagine the pit would look and "feel" quite different.
And I was more thinking these hypothetical travelers may get some information from seeing evidence that a column test etc. was done more than them re-using the same pit for said tests.
¯\_(ツ)_/¯

[Dave B]

Yeah I was more thinking about someone coming across a pit no more than a couple hours later, particularly if it's not windy and the pit doesn't have direct sun exposure. Obviously if it's a windy day or someone comes a across a pit more than a day or so later then I can imagine the pit would look and "feel" quite different.
And I was more thinking these hypothetical travelers may get some information from seeing evidence that a column test etc. was done more than them re-using the same pit for said tests.
¯\_(ツ)_/¯

Yeah, I'd think without knowing the actually results of the tests done in the pit, knowing that someone *had* done a pit doesn't help much. BC skiers should be self sufficient, making their own decisions, and not assuming someone else who was out knew what they were doing or that we can infer information about snow pack stability simply because someone dug a hole in the snow.

[Jorts]

how often when hiking/climbing in winter do you dig snow pits to gauge the state of the snow pack?

Hardly ever. I use them to confirm suspicions about things I generally already know from hand pits or probing with my pole or seasonal history. If there's a relatively low angle slope with sections that are right over that 30 degree line or a convexity, sometimes I'll do an ECT to determine propensity for failure and propagation. If the results are a sudden planar or sudden collapse there's a strong chance I won't ski the slope.

If CAIC goes green mid-winter, and I visit a steeper area I have yet to have gone, sometimes I'll do an ECT there to confirm that green forecast. I do not use pits to make a GO call on a considerable hazard day, but I have used them to make a NO GO call on low hazard days.

The cleaner the pit, the more reliable the results for assessment. You should be able to dig one and perform an ECT in under 10 min.

wouldn't it be more helpful to others touring in the back-country to leave the pit open so they can see the state of the snowpack more easily?

No. You have no way of gauging the results of what they did in the pit. Or knowing how old it is. Once the snowpack is exposed to the elements it changes rapidly. Leaving it behind would be pointless.

One thing to be aware of, you want to dig pits in places that are not often skied. If you dig a pit in an area with a history of skiing, the ski tracks will completely throw off the mid pack layers you find. (What's this strange discontinuous melt freeze layer amongst a bunch of faceting snow?... oh it's snow that was compressed by a ski track).

[TomPierce]

I really don't dig pits much at all anymore, mainly because I use terrain to avoid slide prone areas altogether, e.g. ridgelines, boulderfields, etc. I took avalanche training many years ago, have dug many pits in the subsequent years and I think it's interesting to see the various layers, which of course vary by slope, aspect, etc and years as well, i.e. some years are obviously much worse than others. It's fun to do, you get a sense of what's beneath your feet.

But speaking only from my perspective, a snow pit is a woefully inadequate diagnostic tool and I'd be an utter fool for staking my life or another person's life on such a diagnosis.

-Tom

[TomPierce]

Alec,

I think anyone who ventures out into the true winter backcountry (vs. someone who just hops out of the car for a quater mile winter walk at Loveland Pass) should take an avalanche course. Take any course you can, but of course you'd get more out of a good course, esp a classroom theory day coupled with a field day where you dig pits, do a practice rescue, etc.

Totally my opinion: I think avalanche education has gone down a path of making things seem more technical, e.g. labeling layers of snow, etc. Sure, makes it arguably more consistent, but I wonder if it's also trying to make it seem more like predictive engineering, "The T5 layer's facets have crystallized near X47" (totally being sarcastic). Sort of a "science will save you" theme. Don't get me wrong, I think avalanche education is generally always good, but pits for example: The force applied to cause layer separation is highly variable by user, and IMO a pit is at best predictive for that spot at that altitude at that time, etc. Some information is certainly better than none, but I wouldn't risk a life on a go/no-go snow pit analysis. Just me.

I'd also look at terrain analysis, there used to be some really thought provoking (i.e. difficult) online exercises put out by a Canadian avalanche education group, totally free, probably still there. And don't forget the fuzzy science of heueristics (sp?), e.g. expert halo, etc. Worth thinking about and tucking away in the mental arsenal.

Just my opinions.

-Tom

[JacerJack]

I do not use pits to make a GO call on a considerable hazard day, but I have used them to make a NO GO call on low hazard days.

+1 I always assume the worst in the snowpack, even on low hazard days (especially if it dips into the green during mid-winter).

To answer the original question, while it's fun (and important) to dig your own pits to get acquainted with the snowpack, I always take my own results with a grain of salt. Even after completing an AIARE 2 course, I'm woefully underqualified compared to many of the avalanche professionals that we have in CO. Colorado has some of the best avalanche forecasters in the world, so I've found it's best to leave the snow science to them and just get really good at interpreting their forecasts and data. If on a particular day, they say to avoid N-SE slopes over 30 degrees at or above treeline, that's exactly what I'm going to do (and yes, I check the forecast before winter hiking/climbing too, not just skiing). I think people can really overcomplicate things by thinking they can outsmart the forecasters by digging their own pits... Not at all implying that's what you're doing here, but it's a slippery slope (pun fully intended )

[Monster5]

Agree, Tom. I always thought it interesting to equate developing snow stability science to "developed" geotechnical slope stability science. I've seen a few papers on it. The principles are similar but jargon quite different. One can certainly adapt many of the GIS overlays and other predictive models to given areas.
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I never base a go/no go decision on snow pits or, more commonly it seems, on having avy rescue equipment and certs. The best mitigation is avoidance, and that's possible on perhaps 70% of 14ers based on route choice alone. No reason to touch the others without a good forecast and weather watching, and our weather has been trending more and more tame over the years.
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Sometimes in the most "extreme" avy conditions in CO, you've gotta be actively seeking the snow out to find enough to slide. Aka skiers/snow boarders. There are usually bare or safer alternatives if one's goal is simply to get from point A to B.

[Carl_Healy]

...Carl is a smarter guy than myself, so curious as to when/where pits are worthy

I wouldn't say smart, just always willing to learn!

Thanks for the comments and knowledge all!