Throttle Back – Forecasters Bulletin

If you’re heading into the mountains this weekend, go cautiously and watch for the possibility of human-triggered avalanches. The snowpack is not yet trustworthy following the recent big storm. This applies whether you’re sleddin’, shreddin’ or snowshoein’.

Pat on the Back
It’s been a great season. You have to go back to 1980 to find a winter in Canada with an equally low number of fatality statistics for this point in the season. That’s 33 years! And there are many times the number of recreationists using the mountains now compared to 33 years ago!

So let’s give ourselves a pat on the back. Collectively, we’re doing things right. Word has been going out when conditions are bad, and (for the most part) folks have been responding by making good terrain choices. When conditions have been good, folks have been hitting the higher/steeper/gnarlier lines and having a blast. It’s helped that this year the distinction between good conditions and dangerous conditions has been fairly obvious. Still, a big part of this year’s success has been due to the diligence and good decision making of the mountain user group.

Winter’s Back

Actually, it was never over in the higher bowls where people like to go riding. Lower down, it feels more like spring. Or maybe more like a deluge. In many areas, the recent pineapple express dropped a tonne of rain in the valleys and a mix of rain and snow higher up.

It’s what that new snow/rain is sitting on that has me a little worried. The recent weak layer from around March 10th has been very reactive, with storm snow above this layer reported to be very easily triggered. At lower elevations, once things cool down and the rain-soaked snow freezes, I suspect this won’t be much of an issue any more. Higher up, however, above the rain line, or where only a little rain fell, the new precipitation has simply added more load to the snow. This will have done little to stabilize the snowpack when we consider human triggers, but will have increased the potential size of any avalanche releases.

Folks looking to get their winter fix this weekend will be drawn to the higher bowls, to hunt down the good riding conditions. My advice is to travel cautiously and avoid big open lines. It’s too soon after a big storm to trust the snowpack. Small slopes with friendly runouts (no terrain traps) and escape routes are a good choice. Larger slopes, particularly those with steep, convex sections, are best avoided for now.

I’d like to point out that professionals are very much still watching the touchy weak layer from around 12th February. This weak layer was the suspected sliding layer associated with the two fatal avalanches in the second half of February. At higher elevations, I would consider this layer to be still in play in many regions. There is a very real chance a smaller avalanche triggered near the surface may step down to this deeper layer, dramatically increasing its size and destructive force.

Back to Basics
Just because you can see grass and crocuses in your yard doesn’t mean you don’t still need your full winter gear (including your transceiver, probe and shovel) for mountain travel. You also still need your avalanche brain in gear. Bear in mind that when conditions are changing rapidly, like they are at the moment, it becomes even more important to make your own observations to help assess snowpack stability. Be on the lookout for signs of instability. If you see recent avalanche activity, feel whumpfs, or see the snowpack start to crack at your feet or under your sled, you need to back off to more mellow terrain. Also, you need to consider the deeper instabilities. There are fewer observations you can make that will provide accurate information about this type of avalanche problem. The key is diligence, and a commitment to selecting smaller terrain that won’t bite too hard if the snowpack lets you down.

We’ve got your Back
As always, keep checking the bulletins before you head out. We’ll keep you apprised of the latest mountain conditions from our extensive network of observers. Also, make sure you talk to other mountain users from your area who you trust. And it may not be too late to take a course – there are still some providers offering Avalanche Skills Training (AST) courses in the second half of March and even into the first half of April for some regions.

Latest bulletins: www.avalanche.ca/cac/bulletins/latest

AST Courses: www.avalanche.ca/cac/training/ast/courses

By James Floyer, CAC