I was going to skip the annual avalanche blog post, but multiple avalanche fatalities, coupled with many close calls compelled me to type up a few thoughts into a little two part
series. In this post, I will focus on a few
specific factors (snow stability/uncertainty, terrain, and social factors). In the second, I will present two recent decision
making scenarios and how I handled them. Of course these come with the caveat that I am not an avalanche professional, just a skier who has thought a lot about risk and wants to live to a ripe old age running around in the mountains.
How confident are you about snow stability?
It is really important to recognize the level of
uncertainty associated with the snow stability
side of avalanche assessment. I see a
lot of folks who read the avy forecast, dig a pit, spend a lot of time
discussing snow and weather minutia, and draw the exact wrong conclusion. Why? Because it takes A LOT of time in the
backcountry to really understand snow and even know which questions to ask. Think 300 days at least moving in avalanche
terrain and making tricky calls. An
introductory avalanche course helps jump start process, but it
only gets you about 5% of the way there. And remember, avalanche forecasts are often inaccurate, and it is unwise to pin your life on them.
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| Snow assessment gone wrong. A group of younger skiers were digging a pit at this spot when their buddies triggered the slide above them (summit knob at Gash). I don't know what they were finding in the pit, but it didn't translate to smart decision making. I was not impressed. |
With time, backcounry skiers should expend the mental energy required to really understand snow. Be able to answer questions like: what is the biggest avalanche threat on that slope? Am I sure it is just the new snow, and not a more consequential deep instability?
Given the snowpack, what would an avalanche look like on this
slope. How far would it propogate? How far would it run? Could a small slide step down to a more
deeply buried week layer? I heard some
collapsing on the approach. Which layer was collapsing? If the same thing happened on the slope I am thinking of skiing, would it avalanche? It has been warm in the valley, has it been warm enough in the mountains for the new snow to
bond? It is raining. Is that a problem? (in addition to the fact that skiing in the rain does kind of suck…) The weak layer is an ice
crust. How is that different than if the
weak layer is a thick layer of facets? I dug a pit and got high test scores but clean shears, what does that mean? Is the snowpack on the slope I am skiing different than in the pit? If so, what does that mean? Am I sure?
Does this slope have a thin/weak snowpack? If so, is that a problem? Has it snowed enough in the last storm to
activate deep week layers? And on and on and on.
I find it useful to remember that you or someone in your party should
be able to explain why what you are skiing is safe. If you aren't sure about snow stability, that is OK as long as you limit avalanche exposure accordingly.
Where I am at with
snow assessment: With years of experience, both good and bad, I am confident in
a lot of my on-the-fly assessment skills, but fully recognize that they are not
sharp enough to make cutting edge decisions.
I have not taken an Avy 2, and don’t have a firm grasp on a lot of the finer points of snow science. My pit assessments are merely adequate to identify major weak layers deeper in the snowpack, and I rely heavily on
whether or not a weak layer propagates a fracture in an ECT. I am also bad at assessing "stabilish" fresh soft slabs when they they have stabilized enough that shooting cracks and propagation with ski cuts have stopped, but they could still slide in the right spot. Which is fine - I just try to avoid them.
Not sure about snow stability? Use Terrain
It is easy to stay safe in the backcountry without doing much snow stability assessment by paying close attention to terrain. In contrast to snow stability, terrain is visible, and the concepts are fairly basic. With a rudimentary
understanding of everything terrain (slope angle (be able to eyeball to within 3
degrees), wind direction, aspect, position on the slope, tree density, sign of past avalanches,
etc) you can identify slide paths, gauge how consequential an avalanche would be, and avoid avalanche slopes altogether on high hazard days. No snow assessment required other than a basic
awareness that “things are touchy today”.
Just remember, you have to be consistent and conservative with terrain
choices, but within those constraints, you can do a lot out in the mountains. This is an essential skill for solo skiers. This is also how many experienced skiers safely ski day in and day out without ever digging a pit.
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| Considerable avalanche danger. Utilizing windswept ridgelines to confidently ski steep peaks in the heart of Yellowstone. This photo was taken during my first few years of backcountry skiing. I still had a lot of misconceptions about snow assessment, but was extremely diligent about managing terrain and never had a close call. Photo: Kyle Story |
Where I am at with
terrain choice: Having spent countless days in the mountains by myself with no
one to dig me out, I have spent a lot of time micro analyzing terrain and am
comfortable assessing on the fly. I
spent the first three years or so being very conservative with terrain when stability was at all in question. I still
skied a lot of steep stuff, but waited until I knew it was welded. Where I still occasionally fall short is consistency. Most of the close calls I have had are when I
knew stability was suspect, but I skied an avalanche slope anyway on the edges,
thinking it was manageable. I am getting much better in my old age, and when the avalanche danger is stout Moderate or higher, I am usually either on
slopes that will not slide, or am skiing small terrain with a (hopefully) sharp
sense of what is actually manageable. And
as a rule, I don’t ski many steep and exposed lines with more than a few inches
of powder, except in the spring when the underlying snowpack is welded. And I’m OK with that.
An few thoughts on decision making and the human factor
A lot of recent avalanche focus has been on decision making and human/social/pysological factors. I will save a longer rant for another day,
but this stuff is very important, especially in groups. I strongly encourage everyone to spend some time with Powder Magazine's two part series. Here and Here.
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| I triggered this avalanche while traibreaking. There was a foot of new snow with wind. I knew the slope was marginal, but went for it anyway. Human factors include: Group of guys, familiar slope, ego, haste. Stupid Stupid Stupid. (This was several years ago. I think I have gotten smarter since then). |
As an introvert, a lot of the social factor
stuff for me is about communicating well, but a lot is centered around making consistent choices no matter what the
weather/avalanche danger/group size/need to impress that rad, smart skier
girl is. For example, are you touring with a bunch of hard charging dudes? Be aware that any avalanche conversations are
probably going to be minimized. Either look out for yourself, or be the one who initiates an avalanche
conversation (both approaches work). Skiing sidecountry? Be aware that many/most of the people out
there do not know what they are doing, and are probably pushing the avalanche
envelope. Skiing with someone less
experienced, or quiet (like myself)? Be
aware that they might not speak up, and that you need to either
trust their experience, or ask them what they are thinking about stability, and
be able to explain what you are thinking. Just out for an easy spin and not going to push it today? Keep your eyes peeled. The mountains don't care that you think you are taking it easy. The key is consistency.
And remember, there are days when snow quality and stability are great. When this happens you can go big.
And remember, there are days when snow quality and stability are great. When this happens you can go big.
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| Steep, stable powder and 3.000 foot runs. Solo. As good as it gets in the Bitterroot. |
Stay tuned for part two.
Nice post Brian all good points. I would like to hear about how you determine that things are "welded" other than when it is isothermic corn snow. So often around here we get pit results that suggest really low probability but rather high consequences. I really would like to ski more exciting terrain with more confidence in my assessment than I currently have. My nature is to be conservative, I don't want to get hurt or stress anyone out by my getting myself in a situation that will put my partners at risk so I tend to not ski the exciting lines unless someone else more experienced than me confirms my assessment, any thoughts on how to build assessment confidence?
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteHoward - Determining when the snow is welded should be pretty intuitive. The avy forecast should be Low or on the lower end of Moderate. There should be no intuitive reason to believe a consequential avalanche is likely. Snow could be a bunch of things: consolidated spring snow, facets to the ground with no slab, sastruggi, wind scoured aspects without little pocket slabs, bed surfaces (it is not uncommon to be out skiing and find a steep couloir which has already slid, and is quite safe), deep avalanche debris. Hard, old, dense slabs with no boot penetration on slopes over 38 degrees are often stable. The terrain component is really important as well. There are a lot of days when the hazard is isolated to wind loading. With care, you can often ski steep terrain and couloirs as long as you can avoid big wind loaded starting zones. And one more thing, look at SNOTEL gages and start to correlate snow water equivalent with what you are seeing when you go out. An inch of water is about a foot of blower powder. If it has precipitated more then an inch of SWE in the past few days, or more than two inches of SWE in the past week, it is unlikely that avy conditions will be less than a stout Moderate even if there are no other obvious signs of instability.
ReplyDeleteThanks Brian, great information, I genuinely appreciate you taking time to address my questions.
ReplyDelete-Monitor SWE
-ECT sheer cleanly with energy even with a high shoulder tap number, don't ski avy terrain.
Cheers
Howard
Howard - It sounds like you are on the right track. I am serious about the ~300 days of experience thing, so if you have been skiing for less than a decade, chances are you need to be patient and keep asking questions and testing your theories. If you are in the Flathead, you have several advantages. One is an excellent avalanche center. A good strategy is often to use the forecast as a starting point, and test to see if your observations match what they are finding. Also, the Flathead tends to have a semi-costal snowpack which means that at any given time, there will probably only be one or two deeply buried weak layers of concern. If you stay in tune with the snowpack, you should always know which deep layers are a concern. For assessing deep weak layers, I primarily use the avalanche center, listening for collapsing, natural avalanche cycles on the deep layer, and experience with a wide margin of safety. I almost never use pits to justify why a slope is stable. I more use pits to get a basic understanding of the snowpack, and to make sure I am not missing something obvious.
ReplyDeleteThere will often be deep layers in a pit that break with dirty shears at high force. I will usually think about when that interface formed, how long it has had to stabilize, and if there was any chance of a buried facet layer during that time. If I have been tracking the snowpack, and there is no reason to believe the low probablility/high consequence layer is a problem, than I usually don't worry too much about it. If anything shears cleanly with energy in an ECT, I am usually afraid. Also, if the snow structure of a deep weak layer is suspect, then I am usually afraid.
Another good thing to do is to track your observations relative to public observations over several seasons. Did other, bolder skiers trigger avalanches on layers you were finding in a pit? Chances are, they are on the major weak layers (deep, well identified weak layers, or new storm snow) and not the intermediate funky layers you are bound to find in a pit. For example, we dug a pit last weak. I am confident that the on the ground depth hoar is a non-issue on the slope, so we only dug down 3' to my perceived high consequence layer of concern (New year dry spell layer). We did two quick ECTs and found dirty shears at about 18" and on the New year layer on shoulder taps. Since both interfaces were high consequence, and it had snowed 4" of SWE in past two weeks, I proceeded on the assumption that a consequential avalanche was still possible (stout Moderate), but we had a little buffer of stability to work with as long as we avoided big, steep wind loaded slopes. We skied steep terrain, but limited our steep skiing to non-wind loaded and solar aspects. We did ski one steep wind loaded shot, but spent a bunch of time dropping cornices and monkeying around in the wind loaded starting zone.
Thanks for sharing your thoughts on this (and the 2nd post too). Good reminders coming from someone who is out there more than most of us. Best, SG
ReplyDelete