The Snowpack Picture Up North with Grant Statham

British Columbia’s Snowpack has been touchy this winter, particularly in the Interior. We spoke with Canmore-based avalanche forecaster Grant Statham to better understand in a general sense why this season has been atypical in the Interior.

In late December, I left a relatively stable snowpack here in Central Oregon for an uncharacteristically unstable snowpack in Interior British Columbia. When I think of the idea of “interior,” I conjure images of remote, windswept, and even tundra. Where I went, the Sunrise Hut just outside Golden, B.C., wasn’t that kind of interior. Yet, the Interior, as the locals call it, is a vast place with numerous mountain ranges, and as the name suggests, way inland, longer than an as-the-bird-flies distance from the roiling Pacific.

This season, the snowpack there has been touchy in a way that many locals haven’t seen in decades. I knew this heading up there, as the guides I was going with, Rob Copolillo and Nino Guagliano, communicated their concerns. We’d be taking a conservative and tempered approach to the ski terrain. Despite my prior knowledge of the snowpack scene thanks to my regular readings of Avalanche Canda’s website and Rob and Nino’s transparency, I was a bit unnerved while listening to the CBC between Radium Hot Springs and Golden, when a special avalanche warning (SPAW) for BC was announced. When I settled in the motel, I checked out the Avalanche Canada site to read the SPAW — much, if not all, of Interior BC, was shaded red on the SPAW announcement.

After the trip, I contacted Grant Statham in Canmore, Canada, to learn more about what was going on in Western Canada and, in particular, the Interior. I’ll follow this story up with a piece on how Rob and Nino managed the dicey snowpack at the Sunrise Hut during our stay.

Statham lives in Canmore, part of the Canadian Rockies, which lies just east of the Interior. Where I was, outside Golden, is the eastern edge of the Interior. Statham’s primary job is with Parks Canada as a visitor safety specialist; he’s not protecting anybody from bears but is part of a mountain guide team forecasting avalanche danger for the highway systems through several national parks. He’s been forecasting for 35 years and became a guide at 24. Statham is also a part-time consultant and ski guide and is widely published.

What follows is a lightly edited conversation I had with Statham in mid-January.

***

WildSnow: For those unfamiliar with snow in Canada, and thinking very big picture, how would you describe the typical snowpacks in Western Canada?

Grant Statham: The snowpacks are markedly different. On the coast, we have the giant deep snowpacks. Moving inland some, we have what I believe is known as an inter-mountain snowpack, and that’s sort of in the Interior where there’s tons of snow, but it’s not as wet as on the coast. Then by the time you get over to where I am, in the Rockies, you’ve dried right out; we have a Colorado-type snowpack over here, and it’s pretty dry. We’re the last ones to get any moisture out of the storms from the ocean.

We still have a tricky problem here in the Rockies, so not to minimize it, but really, I see the uniqueness in the Interior Ranges where they don’t get this very often.

WildSnow: What specifically makes the snowpack unique this year in the Interior, and what are some of your concerns? We’ve been hearing reports about how unpredictable it is.

Statham: I can start by stating I feel like a mild impostor because I’m in the Rockies. And we’ll be talking about the Interior snowpack, which is to my west by a few hours. And so this winter, in the Rockies, we have facets on the ground all the time, like Colorado. It is a tough winter over here. But, we always have facets on the ground here in the Rockies every year: we have what we call a deep persistent slab problem.

But, the thing is, you don’t have that every year in the Interior. To me, that’s the difference.

When I look west, and I’m reading reports, and looking at snow profiles, and talking to friends, and seeing reports daily, including this morning, of large, deep avalanches, failing on facets and crusts right near the base of the snowpack — that’s not something that you often see in the Interior, and we’ve even seen them on the Coast, and you rarely see them there. These are deep fracture lines propagating long distances, and they’re running on the ground.

I have been through a number of these winters now. I can age myself by referring to the touchy snowpack years. I remember 92’ as bad, 96’ had one of these, and 2003 too. But they’re not that common in the Interior. So you might just say every 10 years, there’s one of these. It’s infrequent.

People who aren’t used to this, they gotta watch it because it’s just different. Especially since the pandemic, we have so many new people who have picked up skiing; I mean, the backcountry is packed, our avalanche course numbers are huge, and Avalanche Canada’s AST (Avalanche Skills Training) program is booming.

There are all these new people out there, relatively new people. A lot of these people have just never really seen a winter like this. They’re different conditions, but you have to treat them differently because there’s this beast at the bottom of the snowpack, and It’s the hardest type of avalanche to predict.

WildSnow: Can you compare this winter so far in the Interior to what you normally might see in terms of a snowpack that maybe is unstable but not unstable to the base?

Statham: To be clear, we’re talking about the Interior. So again, leaving where I am at the moment, a typical Interior season always starts with some snow and rain in October and November, and we’re gonna see some warming events through that. So we inevitably, every year, see some rain. And typically, in November, we get the dreaded November rain crust. We have those pretty much every year.

What happens after that rain crust is what’s really important. We want to know how high that rain crust goes; did it rain to the top of the mountains? If so, we’ll have a rain crest in the avalanche-starting zones.

The best thing that can happen after the rain crust formation is it just keeps on snowing, and we get tons of snow, and that crust eventually just gets pushed to the bottom of the snowpack. We get a big, dense snowpack, and eventually, the crust bonds to the layers above, and we don’t have a problem.

That is commonly how things start in the Interior ranges and the Coast at the base of the snowpack. Then, of course, we’re always dealing with the usual problems, which are the new snow, wind slabs, and it’s common to get surface hoar in the Interior, especially around all those big lakes, say near Revelstoke and south near Nelson.

That always happens. We can expect it; we’re gonna get a clear spell for a few days and get a layer of surface hoar, some more new snow, and then you can trigger those layers too — those are also very tricky.

Here’s the key: in the Interior, we’re not usually worried about the base of the snowpack, which is this lurking thing that’s really hard to predict. That’s the difference in these infrequent years. This is a deep persistent slab winter, where now we actually have facets at the base of the snowpack in a typically strong place.

It takes some adjustment for people because it’s not normal.

Useful Links:
Avalanche Canada
Flexible Forecast: Avalanche Canada
Backcountry Lies We Tell Ourselves: By Ryan Burke
Alpha Angle: How Far Can That Avalanche Go?: By Lou Dawson

WildSnow: In Canada, forecasters use a system of dating the weak or suspect layers in the snowpack by “formation date.”

Statham: That’s right when we get a new weak layer, the day it’s buried, or the day it’s formed, it gets a date. So the day that gets buried, it gets tracked, and we log it in our system, and we follow it. That gives us things to target when we’re looking into snow observations.

For example, we have surface hoar on January 4th. We then will follow it and want to know, what are the test results on the January 4 layer? What’s the distribution? Where are we going to find it?

WildSnow: OK, so let’s circle back to the rain layer and how that can promote instability in some situations, like we are seeing in the Interior.

Statham: So it rains in November, and we have a crust, and there were two things that happened in November. It rained to the top, and there are crusts in the start zones near the top, certainly well above the treeline. And then it didn’t snow, you know, long drought.

That’s the worst case. That’s the worst thing that can happen as we get these rain crusts; even worse, if you get five to 10cm on top of it, it insulates the rain crust, and then it gets cold and clear for a couple of weeks.

I always use the word rot. It rots the crust; essentially, it facets the crust. That is due to variations in the temperature gradient because crusts change how temperature and moisture flow through the snowpack. You can imagine the temperature and the moisture; everything’s moving up from the bottom, from zero degrees on the ground, whatever it is on the air, and then up comes the heat and vapour, so to speak. That’s where we key in at temperature gradients through the snowpack.

So I’m gonna go a little granular here, but crusts alter that pattern, how temperature and moisture move from the ground up through the snowpack, what we call the temperature gradient. When we take temperatures every 10 centimeters, which we do to plot and look at the gradient in the snowpack.

If you have a change of less than one degree for every 10 centimeters, the snow gets stronger and this is rounding.

If you have a change of more than one degree for every 10 centimeters, the snow gets weaker because you get faceting. When you have a dense crust, it alters that gradient: you can imagine all the heat and vapour coming up through the snowpack, and the crust changes the way the it moves through the crust.

The crust creates locally steep (greater than 1 degree per 10 centimeters) temperature gradients right beside the crust, both above and below it, and this creates faceting adjacent to the crusts. You watch that crust evolve over the coming weeks and months. In early December, when it’s now been buried by some snow, you can see it’s getting weaker and weaker above and below that crust.

I haven’t dug in the Interior myself yet so I can’t speak with much authority. But I understand there are also just weak facets, not just the crust, and the bottom of the snowpack is just getting weaker and weaker.

So we’ve got a weak foundation. And now we start to add the load through the month of December until we get to a point when there’s enough load up above it to have a slab, and it can fail on those deep layers.

That’s kind of just the tipping point that we hit, and you saw that Special Avalanche Warning. But we’re gonna see action on that layer again, and we’re gonna see it probably all winter, I would guess; you never know. But these things typically last all winter, or at least until late March or April; they get worse because they get deeper with even more load.

WildSnow: I will say that when we ran through an avalanche drill on my recent trip, I took off my skis, took a step, and sunk to nearly my armpits in faceted snow. Anyhow, with that type of situation set up, what have you seen as the season progresses into January and beyond?

Statham: So my experience has been late January. That really is spooky — we see large avalanches. In previous years, we have seen reports of avalanches with propagations, fracture lines of multiple kilometers, and jumping terrain. They get big. These are the kind of avalanches that take trees and create new avalanche paths and stuff like that. So they’re not that big yet, because it’s early in the winter, and we don’t have that much load. But you know, you wait till six weeks from now, put another meter and a half of dense snow on top of it.

The problem is these layers don’t heal quickly.

They form fast, or pretty fast, four weeks after November and into mid-December; we’ve got it. But the healing process, the reversal of that, takes way longer, and it requires good temperature flows through the snow, and it requires a lot of snow on top of it. We call it pressure sintering. You can imagine two meters of snow pushing down on the base that helps. But it takes a long time. So that’s really the thing with these layers. They’re here. They’re deep. They wake up, which they did for that special warning, and then they kind of go to sleep again. And things seem better. The snow is less reactive. It’s not so obvious. So you’re tempted to step out a little bit, you’re tempted to go into places that you would normally go. Yeah, it looks pretty good. And then you get these random, almost unpredictable avalanches.

WildSnow: Personally, during a year like this, for your own outings, how do you make plans considering the relative avalanche danger?

Statham: We (the guides) use something called Informal X to communicate. It’s actually not the Info X used by forecasters and guides; we considered it to be a little less formal. If you’re a member of the ACMG (Association of Canadian Mountain Guides), then you get access; originally, it was like five of us who emailed each other. But now there are probably, I don’t know, hundreds of people in the ACMG, the guides, and association managers.

I put up a post there recently just asking for some of my colleagues’ experiences from past winters that have been like this, how we’ve got through them and some of the mistakes that we’ve made, and what we’ve learned. asked some of the more seasoned people, “hey, if anybody wants to share past lessons, let’s do it so that we can use them for this winter because here we are, again.”

Guide the terrain, don’t guide the snow.

It’s always terrain, terrain, terrain; it’s all about terrain. You can’t predict the snow in years like this one.

It was amazing. I can’t share it with you, this is supposed to be confidential stuff. But boy, it was interesting. Everybody who responded had 30 years of mileage and really good things to say about how to handle this winter. So much to learn in there. And you know, to summarize it, it was guide the terrain, don’t guide the snow.

It’s always terrain, terrain, terrain; it’s all about terrain. You can’t predict the snow in years like this one.

You have to manage it with terrain and patience. Because there are going to be periods where it doesn’t seem that bad. You’re not going to see any big deep avalanches, and you’re going to start to wonder if we should open that run up, maybe we should start going over there. And we need to be so careful about that tendency.

There were also lots of messages to employers of guided lodges; “don’t push too hard on your staff this winter, do not push them to deliver the big goods. This is not a year for that.”

I guess there are some lessons to sort of summarize what we’ve been talking about for this winter: make it simple. Just guide the terrain, stay in the safer terrain, use the terrain, and don’t expose yourself much. And be patient, you know, just really be patient and understand that it’s going to be tempting to step into a big steep start zone because it hasn’t avalanched yet. So you’re going to be thinking, “Oh, it must be good now,” but I would be really careful with that.