February 20, 2014

Beauty is only skin deep

With two fatalities in Western Canada over the weekend and very large avalanches happening in the region, it looks like we have reached a climax or turning point in the story of our winter.

Today’s video clip is about the size 4 avalanche that occurred today at Island Lake Lodge’s Cabin Bowl in the Lizard Range bulletin region. These types of historic avalanche events can serve as a wake up call to ensure our winter story doesn’t have a sad conclusion.

Today’s Forecaster Blog by Karl Klassen tells the story of that tipping point and also gives some excellent advice on how to keep enjoying the snow during high hazard, and what we might expect in the coming weeks.

Finally it’s winter again. And doesn’t it look great out there right now? Unfortunately, I’m going to sound like the Grinch who stole the powder here but I will finish with a glimmer of hope if you stick with me to the end of another of my fireside chats.

We all know that the early winter drought created weak basal (near the ground) layers. These layers were a major problem when the first blast of winter hit in mid-late December. Remember all those big slides that ran deep in the snowpack or on the ground? Well, those layers adjusted to the load they were subjected to in December and went dormant in January. Dormant as in the Monty Python parrot sketch—“It’s not dead. It’s just sleeping.”

Then we had Drought-Part 2: Return of the endless dry spell. Over a month with only a few dribs and drabs of snow, leaving us with sun crusts, wind crusts, surface hoar (weak, glittery feathery ice crystals) and facets (weak sugary crystals). Pretty crappy riding in a lot of places and tracks, tracks, tracks everywhere else. These conditions prevailed across most of the western Canadian ranges. That was the bad part. The good part? The weather was fabulous, the storm instabilities settled out and bonded, and the deep instabilities locked in. You could ride almost anywhere with impunity. My knees were sore every day I guided in that period but I skied lines with guests that I haven’t touched in four or five years (more on that later). By the end of that four or five weeks though, there were a lot of powder-hungry people all over western Canada, waiting for winter to come back.

And now it looks like winter again. Up to two metres of storm snow in the last 10 days or so. Ohhhhh mannnn, I can just see all you hounds straining at the leash, waiting for the stormy weather to end so you can go SHRED! I’m gearing up too—heading back in for my next guiding shift on Sunday and looking forward to riding Monashee powder instead of whatever that stuff last month was. But—here’s the Grinchy part—right now all this new snow is just lipstick on a pig. We have a beautiful skin of amazing powder lying on one of the crappiest layers we’ve seen in years.

The snow surface that formed during Drought Part 2 was smooth and hard (wind/sun crusts) or weak (surface hoar/facets) and absolutely perfect for NOT bonding to new snow that falls on top. And that’s exactly what’s happened. From the first snowfalls on February 9th or so we’ve been experiencing an avalanche cycle where the storm snow is sliding off that old weak surface. OK, so this is not that unusual. It dumps a metre or more, it avalanches. So what. Just wait it out. And yes, that’s the first part of the equation. But the biggest challenge will come later this week, this weekend, or next week when we transition out of the storm avalanche phase and into the persistent (read avalanche problems lasting longer than you think) avalanche phase.

Here’s my follow-up on the comment about skiing lines I haven’t been on for four or five years. In my profession as a guide, I have learned that patience is a virtue. I know that sometimes I have to wait for conditions to be right before taking on aggressive terrain. I’m not scared of big, complex features but I do respect the potential consequences if I hit them at the wrong time. As a professional guide and a Dad my tolerance for risk is relatively low and over the years I’ve taught myself how to enjoy more moderate terrain and less aggressive objectives as much as the adrenaline-filled days I used to crave all the time. But honestly, sometimes I wait all season or several seasons to ride my favourite big lines because even with a probe, shovel, transceiver, balloon pack, other guides nearby to help if something goes wrong, and all the other safety systems we put in place I’m just not prepared to accept risk the way I used to be. So I don’t ski 007 or The Hourglass or Hot Viking Woman every time it snows, or even every season. Sometimes I’ll even wait for several seasons as I bide my time waiting for everything to be just right. Then, like last month, I go for it, knowing it might be weeks, months or years before I go back to these places again.

You can and should make your own decisions about how you’re going to handle the next few weeks. And if you decide you’re willing to accept more risk than me, I’m good with that. But I do think a decision like that should be a well thought out, well informed and calculated. Too many people just go. All I’m saying is: Think before you go.

OK, enough of being your Dad. Here are some things I’m thinking about in preparation for going into the mountains next weekend for a couple of weeks:

As more snow gets added to the mix, winds blow that snow around, and under the influence of relatively warm temperatures the upper layers of storm snow are settling and becoming slabs. This is subtle right now; I’m not talking hard, drum-skin slab. I’m talking ever so incremental increases in cohesion where the riding is still great but the snow across a slope sticks together a little more every day.

As a slab gains strength by way of this increase in cohesion, the potential for fracture propagation increases. That is, failure travels farther and faster from one part of the slope to another and bigger sections of the slope will fail.

The layer underneath this most recent dump is a bad one. Certainly the worst in a few years. It’s not gaining strength nearly as fast as the overlying slab and it’s not bonding well to the overlying snow yet. And it probably will stay that way for some time—maybe weeks.

1. Looking at the data and comments coming into our office I’m seeing and hearing things like:
-Increasing whumphing (that sickening sound as the entire snowpack collapses beneath you).
-Tricky. Electric. Very touchy. Terrifying.
-Big propagations.

2. Remote triggering (that’s when you trigger a slide from a distance—things are so unstable you don’t even need to be on the slope to initiate an avalanche).
-Surprising lack of reactivity considering how easy it fails in stability tests.
-An increasing number of large avalanches.
-Slopes that were heavily tracked before this storm started are not stable—tracks visible on bed surfaces after avalanche have run.

These are all classic indications of an instability that’s not yet reached its full potential. In my experience, there are two likely scenarios for the next phase:

Scenario one is it keeps snowing, blowing, and stays warm. Under these conditions, natural avalanches (triggered by weather) will continue. The weak layers causing the problem will be wiped out in a lot of places as avalanches run. Where the layers don’t get wiped out, they get crushed into submission by the sheer weight of the overlying snow and eventually they bond. Avalanche danger ratings remain elevated. People remain well attuned to the hazard and risks because the bad weather and obvious avalanche activity that’s constantly occurring along with high danger ratings is an ongoing reminder that caution is required to stay safe.

Scenario two is the stormy weather breaks and we go into a clearing trend—maybe even blue sky and sunny. The weak layers are only wiped out by avalanches on some slopes but not all. Typically they remain on moderate slopes where the downslope pull of gravity isn’t quite enough to overcome the friction (bonds) between the weak layer and the overlying slab. We don’t get enough weight to crush those layers into submission. Natural avalanche activity tapers off, perhaps even stops, but human triggering (the added weight or stress of a skier, sledder, snowboarder) remains an issue. Danger ratings go down because the likelihood of avalanches is decreasing. People are not well attuned to the hazard and risk because they don’t see much in the way of avalanche activity and we tend to have a more positive outlook and make more aggressive decisions in good weather than in bad weather.

Scenario two is the one that worries me. And, looking at the long-range weather forecast it looks like we’re going that way starting sometime this coming weekend or next week.

Adding to the complexity if this picture is all those lingering basal instabilities I referred to with my Monty Python reference above. While I’m not convinced that this particular parrot will wake up over the next week or two I’m sure not going to forget that it’s under my feet in a lot of places and might eventually come back to life.

So, if you’re on my risk tolerance wavelength, here are some things I’ll be doing over the next few weeks:

Wait. Wait longer than usual before moving onto larger, more aggressive terrain. Some runs might have to wait for a couple of weeks or more. Some might be out for the rest of the season. This is especially important for all you folks in the coastal ranges where you’re used to waiting a few days to let things settle down, then going for it. The snowpack you’ve got out there, especially the south coast, is like nothing many of you have dealt with before. Don’t use your coastie tactics and expect them to work this season. You need to think more like the Interior or even the Rockies guys right now.

Don’t trust compaction. Even on slopes where I know there were a ton of tracks before the storm, I’m going to be extremely suspicious until I’ve got pretty solid proof that things are hanging together.

Today is not the same as yesterday. Things are changing a lot every day right now as all this new snow tries to figure out what it’s going to do. Just because nothing happened on a given slope yesterday doesn’t mean it’s ok to go there today—especially if weather changes are occurring (something as simple as sun hitting a slope or temperatures warming up will be a signal for me to pull back a bit and wait to see what happens).

Always remember, it’s a terrain game. Under these conditions more than ever it’s all about terrain. Did I mention that terrain is important? So keep an eye on the terrain. I’m going to avoid terrain traps like the plague. I’ll remember how to enjoy riding small, simple, low-angle, well supported slopes. I’ll be avoiding exposure to large features and cornices overhead

Sharpen my rescue skills. Now’s the time to refresh my companion rescue skills and make sure I and everyone in my group knows how to use the gear and gets some practice. And make sure everything is in good working order: probe and shovel in good shape, transceiver tested and with new batteries, airbag/balloon pack tested with a new fully charged cylinder properly installed.

I sure hope I haven’t turned anyone off going out into the mountains. With the right training, good planning and preparation, and maybe some guidance from more experienced mentors there’s lots of places where you can safely go and have a great time even now with these conditions. And there’s still lots of winter left. If this weekend or next week aren’t right, then we can always wait until March, or April, or even May to get our alpine fix.

Stay safe out there, because we all like happy endings!