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Warm Weather / Weak Layers

Weak Layers

As we approach the halfway point of February, we are yet again facing an onslaught of warmer weather as a ridge of high pressure moves into BC and establishes a pattern of dry weather and warm air aloft, creating quite a strong temperature inversion in many areas. The first half of February produced a series of storms that buried a variety of persistent weak layers under 50-100 cm of snow. These weak layers formed during our last period of dry weather at the end of January and have been a recurring problem these last couple of weeks with multiple skier accidentals across BC.

Enjoying spring-like conditions

Skier reactivity on these layers had started to subside as time passed but with the forecasted warm weather and solar input, we should expect things to become more reactive again as the snow above the weak layer settles into an even more cohesive slab. The possibility of cornice failures and subsequent avalanches triggered by these cornices would be very large if they fail on the persistent weak layers. It will be important to practice conservative terrain choices for the next little while as the nice weather will try and lure us out into bigger terrain and untouched slopes. Be mindful of your overhead hazards and any steeper, unsupported terrain especially around treeline. These weak layers are difficult to pinpoint and will be your classic low probability/high consequence avalanche problem.

Amazing hoar crystals

If you need any more information about your specific area, make sure to visit Avalanche Canada’s website and also make sure you review the Special Public Avalanche Warning they posted last weekend. Results of testing we did on Sunday, Feb 13th clearly reflect the reasoning behind Avalanche Canada’s SPAW. Here are the details, N. aspect, 2040m produced a CTM(14) and a ECTP down 38cms on surface hoar to 10mms. This is a pretty dramatic result and worth noting.

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Early Season Snowpack?

Fully developed snowpack, the base is being laid right now

The first official day of fall has just past and that means our days will start to get noticeably shorter and darker as we get closer to winter and the riding season. This weekend we expect an early season snowfall in most of the mountain regions across the province, with some areas receiving as much as 25-30 centimeters. If you’re a backcountry skier/snowboarder or snowshoer, this is the time to start paying attention to what is going on.

What should we make of the early snowfall? It certainly throws a wrench into the works for folks who were still hoping to get a few alpine hikes and mountain bike rides in, while others will be celebrating Ullr’s early arrival and the promise of a great winter season.

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Linus cruising some nice Coquihalla powder last winter

From an avalanche forecasting perspective, it means we should start to keep track of what happens next because there are a few different ways in which this snowfall could become problematic later this winter. The biggest problem with early season snowfall is that it is a (very) thin snowpack which is susceptible to either melting or weakening – or both.

If the temperatures stay cold and dry, we will see this thin snowpack start to become weaker as the snow starts to facet. With time the snow will consist primarily of large-grained facets. This will then sit at the base of the snowpack and once more snow arrives it becomes depth hoar. These types of layers take a long time to heal and sometimes never fully recover and are with us for the rest of the winter.

Very mature surface hoar

However, if we get a longer stretch of nice, warm and sunny fall weather, the early season snow will melt down to bare ground. It melts faster on sunny aspects but depending on freezing levels and temperatures even shaded aspects could be back down to bare ground. From an avalanche perspective this is probably our best scenario because it means that once the proper winter snowfall arrives, it will fall on bare ground.

If we get a bit of both we could end up with a melt-freeze crust above a weak layer of facets that then becomes buried by our winter snowpack. This in turn may mean ongoing persistent slab problems and eventually deep persistent slab problems. Not good. Luckily it is still only October so there is a reasonable chance we still have another warm spell or two before winter really sets in.

So what can we do from now until the start of winter? Mainly, we should monitor the snowpack and the weather. Keep track of the distribution of any potential future weak layers by keeping tabs on what elevation the snowline stays at and what the snow coverage is like on the different aspects as we get closer to winter. This will help you eliminate elevation bands and aspects that don’t have any snow left on it and shouldn’t be a concern for these particular problem layers going forward. Checking out webcams from highway passes and weather stations to gauge how warm it gets up in the alpine are some of the tools available to us from a distance.

In the meantime, this is a great time of year to take out your winter equipment and give it a once-over, double-check that your transceiver is functioning properly and that everything else is good to go. Industry professionals continue to work on their rescue skills year after year and run scenarios at the beginning of each season. Get outside and practice with your friends and touring partners to make sure everyone remembers what to do in case of an avalanche incident. No time like the present!

Why most of us do this.
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Avalanche Training Backcountry Mountain Culture Mountaineering News Ski Touring Uncategorized

Busy AST Season

We are well on our way through a very busy Avalanche Skills Training season. Subscription to all courses, AST 1 & 2, as well as CRS has been brisk. Conditions have been generally good, quite mild(until now) for most of the winter.

Perfect ski touring conditions
Thank you so much again for the amazing course. I learned so much from you guys, can’t wait to put those skills to use in the backcountry.” Jessica

We had amazing conditions in the Coquihalla for our AST 2 course this past weekend, over 100cms of storm snow, very light winds and moderate temps. Snowpack was a bit spicy, had to select conservative terrain.

You will definitely see me on another course next year with you. Thx. Amanda

I was surprised, given the dodgey road conditions, how many folks actually ventured out to the Coquihalla on the weekend. Avalanche Canada’s MIN report was lit up. Ride safe out there.

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Avalanche Training Backcountry Mountain Culture Mountaineering News Ski Touring

What Will Winter Courses & Ski Touring Look Like

It’s been hitting the high 30’s in Kamloops nearly everyday since the middle of July, so it’s hard to think about ski touring and avalanche courses. But winter really is just around the corner. We are all wondering how the Covid-19 pandemic, and the resulting, necessary measures to combat the spread of the virus will affect our winter activities.

I am very confident that we can deliver the Avalanche Skills Training 1 & 2, and Companion Rescue Skills course in an effective and enjoyable fashion, while meeting all the requirements set up by WorkSafeBC, the Provincial Health Office and the BC Centre for Disease Control. The classroom portion of all courses will be delivered online, and all necessary protocols will be employed during the field portions of the courses. Our courses nearly always run at capacity, so sign-up early.

I have decided to hit the pause button on any ski touring trips, at least for the time being. I prefer to wait and see if, and how the 2nd or 3rd wave of the pandemic manifests itself. I am going to try and run our very popular AST 2+ course, but only if I am completely confident if can be done in an safe manner. I will make a decision on that in early October.

Take good care, Brad