Managing Avalanche Risk Part 8: Validation in Action

In Part 7, we went over how and why you need to constantly validate your hazard assessment and reassess your trip plan, from before you walk out the door until you are back in the car. What follows is a story describing a typical day in the field, which will give you an idea of what the validation and replanning process actually looks like.  

I’d been eyeing a large, north-facing alpine bowl for quite a while. After keeping tabs on the avalanche forecast for weeks, there were no avalanche problems listed. Danger was a “green brick” of low at all elevations. My friends and I decided to go on Saturday.

Where I live, forecasts are issued in the afternoon and the forecast for that Saturday was issued with a timestamp of 4:00 p.m. Friday. Danger was rated as alpine: moderate; treeline: low; below treeline; low. And we noted size 1 to 1.5 wind slabs were listed as possible on east aspects in the alpine. So clearly something was changing. Digging a bit deeper, we saw the weather outlook in the forecast indicated 20 cm of new snow was expected by Saturday morning, combined with light west winds and temps of -10o C. This explained what was driving the change.

Based on the forecast, our Friday evening hazard/risk assessment process resulted in a run list that avoided east aspect slopes in the alpine. Our north-facing objective was not going to be affected by the predicted conditions, so we rated it green on the run list and made it our Plan A as we had hoped. But, given that things were changing, we were primed to keep a close eye on things.

Early Saturday morning I started my pre-departure validation process. This involved first checking the avalanche forecast to see if an update had been issued: the timestamp was still 4:00 p.m. Friday. With a theory and plan that were 12 hours old, no updated avalanche forecast, and knowing an extended period of good weather and low danger were starting to change, I knew I needed to dig a little deeper.

“It was obvious our Plan A to ski a large north-facing bowl was no longer an option”

First, I looked at weather reports and weather stations in the vicinity of my Plan A trip. The morning snow report at a nearby ski area and readings from nearby a weather station indicated up to 40 cm had fallen overnight with moderate to strong southerly winds and temps of -5 o C. Then I went to my go-to weather forecast and reviewed for the morning update with a timestamp of 6:00 a.m. Saturday, which indicated another 15 cm of new snow was expected in the coming day with moderate southerly winds and temps steady around -5 o C.

Compared to what we had anticipated, the amount of overnight snow was significantly greater, the wind was stronger and from a different direction, and temperatures were warmer. Clearly a hazard and risk reassessment was in the cards, which led to a revised theory. Based on what we were seeing in morning information we knew the danger was already higher than what was described in the avalanche forecast issued the previous day. Based on morning observations and the updated weather forecast we figured that larger wind slabs were likely on north aspects, almost certainly in the alpine and perhaps lower as well. Our run list now had big swaths of red on north slopes in the alpine and at treeline, and it was obvious our Plan A to ski a large north-facing bowl was no longer an option.

Make continuous observations about wind and weather when you’re in the field—things can change faster than you think.

It’s at this point where, even if you’ve redone your hazard and risk assessments, things can fall apart. This is not the time to be arguing with your friends about what to do now that Plan A is out the window. Standing at the figurative and literal doorstep is not when you want to be devising your Plan B—you’re going to be rushed, you’re probably going to miss something, and you’re likely to leave the house with a flawed, ill-conceived plan.

Fortunately, as I’ve said many times in previous articles, I had a couple of backup plans ready to go. So there was no arguing, and we didn’t have to re-plan; it was just a matter of choosing from one of our pre-built backup plans. Knowing the forecast from yesterday afternoon was off and with conditions changing quickly I wanted a Plan B with lots of options and a pretty big margin of safety. This would allow me to ease into my day as I developed a better idea of what was really happening out there. In this case, Plan B was a west-facing area with a gentle, very low-risk up-track to treeline. From there we had numerous options, including going higher into more aggressive alpine terrain or skiing several lines with a variety of inclines and terrain configurations at and below treeline.

“Standing at the figurative and literal doorstep is not when you want to be devising your Plan B”

With pre-departure validation complete, the moment I stepped out the door I started my field validation—an ongoing process of looking for new information, updating my hazard assessment, revising my risk analysis, and reviewing the appropriateness of my plan. In this case, I began while driving—looking at the peaks and slopes I could see from the road to see if I could tell what the weather was doing at upper elevations and if there were any signs of avalanche activity.

At the trailhead, I checked in with the group and then, in my field notebook beside my theories and plans for the day, I recorded the first weather observation of the day: plumes of snow blowing off the peaks from a what looked like a strong upper-level southerly wind. At valley bottom, we measured 35 cm of new snow, a temperature of -4, calm winds, and snow falling at about 2 cm per hour. This was in the ballpark of what we expected after updating of our hazard/risk/plan, so after a gut-check, everyone felt comfortable continuing.

While traveling and at breaks, we shared our observations: Temperature was steady, but it was snowing harder than before, and a gusty variable direction wind was moving the tops of trees. We saw no cracking around our skis in the skin track and heard no whumfing sounds. Higher up, we stopped in a sheltered spot where we measured 45 cm of new snow and, above us where the trees thinned out, observed moderate cross-slope winds causing snow to drift across the slopes. With poor visibility limiting our view into the alpine, my spidey senses started tingling. Things looked and felt worse than we’d expected even after the changes we’d made in the pre-departure validation. But where we were standing, the snow felt cold, dry, and fluffy—perfect powder.

“The desire to ski knee-deep fluff is incredibly powerful, and anticipating it will cause your fun-meter to rise. But as the fun-meter rises, the smart-meter tends to fall.”

This is the point where you need to be extremely careful about what to do next.

At this point I did the thing that’s very difficult in these situations: I gathered my group and pulled out my notebook, then we re-assessed hazard and risk. As a result, we crossed off a bunch of green runs on our run list. Anything in the alpine was out, no matter the aspect. Large, steep, or convex treeline features also got the red pen, as did anything that had signs of wind effect. And we made a mental note that even on less steep, planar slopes, we’d be super cautious around terrain traps—even small ones like tree wells where even a small sluff could have serious consequences. During our gut-check, none of us felt particularly stressed because we all knew we were dialing it back and had good options for nice skiing.

When in the field, Klassen advises to never, ever make a red you previously marked red green, even if conditions are better than you expected. It’s likely that your fun-meter is overriding your smart-meter.

We went a little higher then near treeline and made a plan to manage our group to ensure no one slipped into terrain that wasn’t appropriate. We partnered up so everyone had someone who would keep an eye out for them.

I routinely get some gentle ribbing from my colleagues about my run selection routine. When I’ve got the option, I almost always pick something quite safe (aka boring) for the first run or two, even when things look pretty good. Ideally these first runs are ones I’m familiar with and have some very small, low-risk indicator features where I can ski-test stability with minimal risk. I know people think I’m overly conservative—but I can say without reservation that many of my most serious close calls have occurred when I’m over-confident and tackle more aggressive terrain without having checked things out first.

On my fifth turn, I felt a subtle change—the snow suddenly felt just a bit stiffer. We regrouped and I carefully approached a small roll and gave it a kick while my group watched me form a safe spot. And even with no sign of significant wind effect, a small 50 cm-thick slab popped off. The final piece of the puzzle clicked into place—not only was there a wind slab problem in the alpine and at treeline, we also had a storm slab problem at lower elevations in more sheltered terrain. We immediately scampered off to yo-yo moderate slopes in the mature timber.

This story is based on a real trip and describes the kinds of observations you might make on any given day. If you follow carefully, you’ll find lot of places in this narrative where lack of focus, a less-than-ideal validation process, missing something, or even not doing a gut-check with your group could produce far less-desirable outcomes. Remember my story in Part 7. And don’t forget:

  • You’re pretty much always wrong about something—it’s important to accept that.
  • Never stop observing and constantly do everything you can to figure out what you’ve missed before it bites you in the butt.
  • Use your notebook. Write down what you are seeing so you can compare that with your previously recorded hazard/risk assessment and trip plan.
  • Things can change fast—don’t get caught by surprise.
  • Recap, review, and do a retrospective at the end of the day to maximize learning and improve your understanding.

One final word on gut-checks: Be extremely suspect when your gut says it’s better than you thought and it’s OK to get more aggressive. This is almost always the fun-meter talking and drowning out the smart-meter. I never change red runs to green in the field. If everything checks out after my first more conservative line I might ski more aggressive green runs, but never a red one. On the other hand, if my gut is fluttering and it feels like something’s wrong, I’m very quick to pull back into less aggressive terrain, even if just to give me time and space to let the smart-meter do some work and test things out on safer terrain before committing to something steeper.

Karl Klassen took his first professional avalanche course in 1979 and spent the next 40 years working as a forecaster, guide, educator, and mentoring up and coming forecasters and guides. During that time he also sat on the Association of Canadian Mountain Guides board of directors including serving as vice president, president, then as executive director. He joined Avalanche Canada in 2004 as a public avalanche forecaster and became the warning service manager in 2009. Recently retired, he lives in Revelstoke, B.C., where he spends his time cycling in the summer and skiing in the winter.

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