This weekend, Avalanche Canada, in partnership with Parks Canada, issued a Special Public Avalanche Warning (SPAW) for several regions in the southern half of BC and western Alberta. Our concern is the warm temperatures and clear skies in the forecast, which will destabilize buried weak layers in the snowpack.

We have written previous articles detailing activity associated with these layers, including this blog from Dec 30 and this photo essay from Jan 5. The large, spooky, mostly human-triggered persistent slab avalanches on the December layer really makes the hairs on the back of my neck stand up!

I’ll add a couple of more recent images to hammer home the point: the December weak layer cannot be trusted. 

This skier triggered event occurred at North Tombstone in the Lizard Flathead region and was submitted to the Mountain Information Network on Jan 15. Credit: MIN user FBS.

This size 4 avalanche occurred in the Sea to Sky region on January 15. This gives a harrowing perspective of the scale that we’re talking about here. There are additional photos of this event at the bottom of this article. Photo credit: Powder Mountain Snowmobile Club.

Previous patterns of avalanche activity have told us that the December layer is most likely to become active during periods of warming. Guess what? There is a big, warm ridge poised to affect western Canada starting today (Friday Jan 21), extending through the weekend and into the start of next week.

There are some nuances to how the warm weather is likely to come in, depending on where you are. Looking at the map below, we can divide the area of concern into two broad zones: a coastal zone that also includes much of the Kootenay Boundary region, and an interior/Rockies zone.

In the coastal/Kootenay Boundary zone, we’re expecting broad-scale warming that will affect all elevations. You can see this illustrated in a different way using a freezing level timeline below.

This freezing level timeline is for Brohm Ridge north of Squamish in the Sea to Sky region. The bold red line indicates the freezing level and the zone of warm air is annotated on the chart. By around noon on Saturday, warm air is expected at all elevations.

Contrast the pattern above with a freezing level timeline from the interior/Rockies zone.

This freezing level timeline is for Fidelity Mountain in Glacier National Park. The upper, oval-shaped line marked with an “0” indicates an inversion, with above-freezing temperatures at higher elevations. In the interior/Rockies zone, we’re more likely to see cooler mid-elevation temperatures, but alpine areas will be warm with plenty of sunshine.

The likelihood of an avalanche will be linked to three main factors this weekend: how warm it is; how sunny it is; and the structure of the snowpack.

Areas that harbour weak layers and get hit with a double whammy of warm temperatures and sun are the most likely to produce very large avalanches. However, where the snowpack structure is inherently weak, experiencing only one of these weather factors (either warming or sunshine) may be sufficient to trigger a large avalanche.

Many professionals have described the current snowpack as “untrustworthy”. Combine that with a very significant warm-up and it suggests this weekend is not the time to seek out big lines. If very large avalanches do occur, keep in mind they can run beyond historic path boundaries and trim lines. So it is essential to understand where you are in the terrain and what is above you at all times. 

Best advice is to stick to simple and/or small terrain that is insufficient to result in a burial if the slope was to slide. Find a low angled slope and soak up some rays!

Additional photos of the Jan 17 size 4 avalanche in the Sea to Sky region. Photo credits: Powder Mountain Snowmobile Club.

Avalanche Canada has issued a Special Public Avalanche Warning. Read on for an explanation of what forecasters are thinking.

Untrustworthy snow - explaining the SPAW

Since posting the original article on this subject, several questions have come up. In this follow-up I’ll do my best to respond but remember I’m a guide and avalanche forecaster, not an electrical engineer. I can’t offer definitive answers on the more technical questions, but I can give you my perspective as an avalanche practitioner and pass on what I’ve learned by talking to experts in the field. 

Question 1: Does airplane mode make any difference?

On my phone, airplane mode turns off some but not all transmit/receive functions. When airplane mode is on, Wi-Fi and cell signals are turned off but:

·        Bluetooth remains active; and

·        I’m still getting positional and tracking functionality in mapping apps, so GPS remains enabled. 

Given this, it’s my opinion that the only way to eliminate potential active interference from your phone is to turn it off. 

We know turning off isn’t realistic or practical in all circumstances. So, if you decide not to power down completely, then turn off functions you don’t need (e.g., Bluetooth) and using airplane mode are at least a partial solution and it’s probably better than nothing. 

Question 2: What about heated clothing, heated googles, googles with fans?

Anything that uses electricity is a potential source of interference. When these items are turned on, you’re dealing with active interference. And even when turned off, the battery, metal components, and wires in the equipment are potential sources of passive interference. The more wiring and the more current being used, the more I worry about interference. And anything that surrounds or covers the transceiver is a no-go.

So, heated jackets—nope; not ever in any circumstances. Heated gloves must be turned off and stowed in your pack when searching. Same for goggles. Heated socks should be turned off and be careful to keep your distance when you’re in fine search mode, with your transceiver close to the ground and near your feet.

Question 3: Many snowmobiles have Bluetooth. Will that make a difference?

Even without Bluetooth, sleds are a source of active interference when they are running. Electricity is flowing and that creates an electromagnetic field. 

And yes, a sled with Bluetooth adds another dimension to the problem. I’m not sure how Bluetooth works in these sleds. If the Bluetooth still functions when the engine is off, then you need to figure out how to turn it off or you need to keep it 25m away from the search area. 

Electronic devices on newer sleds may cause interference. 

If, like other electrical activity, Bluetooth gets shut down when you turn the machine off, then you are just dealing with a rather big chunk of metal which is, of course, a potential source of passive interference. 

Question 4: Are some brands of transceiver better than others in terms of interference? 

I’m not aware of any research or test results that indicate a difference in transceiver brands regarding this issue. Given that all transceivers use the same frequency and the same fundamental principles to send and search for signals, I suspect there’s little or no difference between brands. 

If you’re concerned, I suggest contacting the manufacturer to see if there are brand-specific features or functions for managing/mitigating interference, then choosing a transceiver that you’re most comfortable with.

 Question 5: What about medical devices?

Any medical device that has metal or foil components must be considered a potential source of passive interference. Any medical device that has a battery, uses electricity, and/or sends/receives signals is a potential source of active interference. 

Now, with medical devices we’re solidly in the realm of balancing risks. Obviously, you don’t want to turn off or disable a device that’s keeping you healthy and alive. So, you’ll need to figure out how to mitigate interference while using these devices.

I strongly suggest you check owner’s manuals or contact the manufacturer of your medical device and transceiver for advice. Barring contrary advice from the manufacturer, at least keep your transceiver a minimum of 20cm away from your medical device when in send mode and 50cm away in search mode. And learn the strip search technique in case you do end up in a situation where you can’t fully mitigate interference.

If you are getting signs of interference near power lines, I can’t think of any way to mitigate this other than learning the strip search technique. Same goes for buildings and electrical machinery, motors, etc. 

 Question 7: Do smartwatches interfere with transceivers?

I can’t think of any situation where a smartwatch is an essential piece of equipment, although I admit I’ve never used one so perhaps I’m wrong. My advice is turn off your smartwatch and stow it in your pack, if not at all times, then for sure when searching.

I completely forgot to discuss packs and airbags in my original article. So, here’s my take.

All packs are potential sources of interference—there could be metal components (e.g., buckles or stays) and almost certainly there are metal contents (shovel, probe, etc.). No matter whether it’s an airbag or not, your pack is an essential piece of gear. In most companion rescue situations, dumping your pack isn’t a realistic option. 

Airbags driven by a compressed gas canister can be treated as a source of passive interference. Figure out where the metal components are (remember there are probably metal parts or wires involved in the trigger mechanism) and wear your transceiver in a way that maintains at least 20cm separation from those components. Battery-powered, fan-driven airbags require the same 20cm separation when in send mode. 

Things change when in search mode. If you’re using a compressed gas airbag, it is a source of passive interference, and you need to keep your transceiver at least 50 cm away. You can usually achieve this by holding your transceiver in front of you and on the opposite hand from an airbag trigger.

A battery-powered, fan-driven bag is a different story. Like any other electrical device, it’s a potential source of active interference. You must decide whether it’s safe to turn the airbag off while searching. If yes, then do so and use the same 50cm separation as described above for passive interference. But if you’re in a situation where you don’t feel you can turn it off, you’ll need to mitigate as best you can. Change where you hold the transceiver while searching, shift the pack a bit to increase the distance from the transceiver as much as possible, and, if all else fails, use strip search techniques. 

 Airbags and radios can both be sources of interference. 

Question 9: How do I test for interference?

This is a highly complex problem that defies a simple ‘one size fits all’ approach to testing, given the huge array of potential connections and interactions between devices and signals. The experts I consulted were very reluctant to consider testing as a solution to this problem, saying that there’s no surefire way to provide definitive answers. 

With no comprehensive guidance on how to test effectively, my real-world strategy revolves around preparation, awareness, and backup search strategies. Here is my approach:

1.      Turn non-essential devices off and stow them in my pack. Maintain adequate distances between transceiver and interference sources.

2.      Stay vigilant. If I see strange or unexpected behaviour when working with a transceiver, recognize problems early and assume it’s interference.

3.      Mitigate the source(s) of interference.

4.      Use strip search techniques if adequate mitigation isn’t possible. 

If you go to the International Snow Science Workshop archive and put the word interference in the search field, you’ll find links to some historical papers on the topic. A Google search on “avalanche transceiver interference” will turn up some additional information. And the coming issue of The Avalanche Journal has an article on interference that contains some test results.

 Question 10: I’m wondering if a Faraday pouch or lining my phone pocket with Faraday tape would block the interference caused by the phone signal?

Faraday tape and fabric is intended to block electromagnetic radiation. In theory, keeping your devices in a Faraday bag or pocket would stop potential active interference. But this would also block incoming calls and communications with other devices. Similarly, a navigation device would not be able to receive GPS signals so tracking functions won’t work while the device is in a Faraday enclosure.

So, while there are probably some potential benefits for specific scenarios, you’re going to have to live with limitations. If you do decide to go this way, remember that the Faraday enclosure is an additional source of passive interference and will almost certainly be highly effective in blocking transceiver signals if you’re not careful. Just like you keep it away from other metal or foil objects, be sure to keep your transceiver away from a Faraday pouch or pocket.

 Forecasting supervisor, James Floyer, checks his phone before turning it off and stowing it away from his transceiver. 

Interference and Avalanche Transceivers Part 2

In last week’s blog we discussed the uncertain and spotty nature of a persistent slab avalanche problem that’s associated with the early December crust and facet layer. Since then, we have seen several notable avalanches involving this layer in southeastern BC. We can now say with greater confidence that this problem is a major concern in several regions including the Kootenay-Boundary, Purcells, Lizard-Flathead, and South Rockies.

The following photos illustrate the type of terrain where this problem is found as well as the size of avalanches that can result. We’ll provide some basic details about each avalanche, but you can click the links to read the detailed reports submitted to the Mountain Information Network.

Jan 4: A very large (size 3.5) avalanche at Pedley Pass (east of Invermere) remotely triggered by skiers travelling along the ridgetop. MIN report from Tyson Rettie.

Jan 2: Skier-triggered avalanche at Leach in the Lizard-Flathead region. MIN report from mattd6178.

Footage of a skier-triggered size 3.5 (very large) avalanche on the Whale's Back near Whitewater Ski Resort on Dec. 31, 2021. By Bobbi Poirier/Kootenay Valley Helicopters

Whale's Back avalanche

Dec 31: Skier-triggered avalanche on Whales Back near Whitewater in the Kootenay-Boundary region. MIN reports from luquasar, ezralloyd26, and kellytooleski. Video footage from Bobbi Poirier/Kootenay Valley Helicopters.

Dec 30: Skier-triggered avalanche on Serac Ridge in Kootenay National Park. MIN report from Parks Canada snow safety.

Dec 28: Natural avalanche on Mt. Plewman in Rossland range in the Kootenay-Boundary region. MIN report from goingupthegrundy.

Dec 27: Skier-triggered avalanche on Evening Ridge near Whitewater in the Kootenay-Boundary region. MIN report from kylegorenko. Photo credits:Jason Wishlow

Photos of recent persistent slab avalanches in the southern interior

One month ago, the stream of atmospheric rivers that flooded parts of British Columbia came to an end. When temperatures subsequently cooled, the mountains of southern BC and Alberta were left covered by a thick crust that extended into the alpine. At that point we were unsure how this crust would impact future conditions. Over the last month, we’ve developed an understanding on how this problem has evolved.

As snow began accumulating in early December, weak faceted snow formed above the crust in some, but not all, locations. What emerged was a spatially variable persistent slab problem. Words like “spotty”, “patchy”, and “spooky” were used to describe problematic areas.

Persistent slab avalanches have been observed over the past few weeks in most forecast regions, including the Sea to Sky, South Coast Inland, North and South Columbias, Kootenay-Boundary, Purcells, Lizard-Flathead, and South Rockies. The most evident pattern was that the majority of avalanches occurred around treeline elevations, between 1,700–2,100 m depending on the region. But there have not really been any other clear trends.

There have not been many periods when avalanche activity on these layers spiked, but rather we’ve seen a handful of large avalanches reported each day. The problem has persisted and our forecasts have featured sustained elevated danger ratings and advised choosing conservative terrain to manage this problem.

Snowmobile-triggered avalanche in the Sea to Sky region from Dec 20 (MIN report from David Dobson).

Skier-triggered avalanche in the Columbia Mountains from Dec 26.

As time passes, this persistent weak layer will gradually strengthen and avalanches will become more difficult to trigger. It will likely become a low-probability, high-consequence scenario.

This is likely already the case in coastal regions, where this layer is buried 100–200 cm deep. We have started to see a declining trend in avalanches, with the most recent avalanches triggered in shallow rocky start zones where the weak layer was closer to the surface. In the interior, where the weak layer is only 50–150 cm deep, notable avalanche activity has continued since Christmas.

In either case, the spotty reactivity of this problem makes it tricky to manage. As an example, we may have 10 slopes that fit the criteria for this avalanche problem, but only see reactivity on one of those slopes, with virtually no indication of which slope it will be.

To manage this problem, one would ideally obtain a strong grasp on its distribution in one’s local area, but this is only really possible with intimate terrain and snowpack knowledge. Realistically, you should exercise patience and be willing to avoid suspect slopes. This requires great discipline, as we will not always experience direct feedback from the avalanche problem and it doesn’t scream “dangerous!” the way a touchy storm slab problem does.

In this case, we can say the most suspect slopes are ones steeper than 35 degrees around treeline elevations. Be especially careful where the layer is buried by less than a metre of snow, or where the snowpack transitions from thick to thin spots. In this terrain, you should exercise good travel habits and keep in mind the potential for large, destructive avalanches.

And, of course, check the avalanche forecast to get the latest recommendations about how this problem is evolving in your region. We wish you a happy and safe New Year!

An update on the lasting impact of the atmospheric rivers

Don't always trust a robust crust

A screenshot from a video of Chris Rubens performing a real avalanche rescue near Revelstoke in January 2021. The video is a testament to the value of practicing companion rescue.

'Practice makes perfect. Better yet, practice makes progress. Practicing companion rescue is an ongoing part of being an active backcountry user. It builds muscle memory we can tap into when it gets real, and it can always be worked on to refresh and recalibrate.

In a recent Avalanche Canada webinar, I had the chance to chat with pro skier and Avalanche Canada ambassador Chris Rubens about a real companion rescue that happened in January 2021. Chris talked about getting into a “flow state” during the incident and how he felt like “auto-pilot” took over. This is a best-case scenario—so long as your auto-pilot knows what to do. We found out that Chris’ auto-pilot knew exactly what to do.

“We know now because (the duration of the entire rescue) was only 90 seconds,” Chris told the watching audience. “So many different thoughts go through your head, but it was really going through exactly what we practice so much, but not even really thinking about it.” 

The big take home for me in this story is that this was the first time Chris had ever used his transceiver in a real incident. But it was clear to everyone watching that his training had paid off. Chris was able to see the big picture and act quickly and efficiently thanks to his years of experience and diligent practice in companion rescue. This is crucial, because you have just 10 minutes when the odds of recovering a buried victim alive is at 80%. After that 10-minute window, the chances of survival drop steeply.

The avalanche survival curve shows the odds of surviving an avalanche drop rapidly after 10 minutes.

We learn so much from other people’s rescue stories and I see it as a free lesson that we all can get better from. There is some great GoPro footage from Chris’s incident and watching from this perspective helps us build a realistic picture of what it would be like to be doing a live companion rescue. Check out this edit of the rescue by Forecast Ski Magazine.

Revelstoke Backcountry Avalanche with Chris Rubens & Noah Morrison

One of the biggest challenges with companion rescue practice is making the stakes seem real so you can do it effectively and learn where you need work. Adding a bit of realism can go a long way to finding those gaps in your plan and skill set. Here’s how we do it as professionals:

When we set up a practice site we try to work in snow that is realistic, with a scuffed up area tracked by sleds or skis, or—even better—a disturbed area like an old debris pile. Ideally we practice on a slope, not just flat ground, and an area preferably over 100 m long and 100 m wide.

We start simple by burying one transceiver deep enough that we have to work to find it. If the transceiver is buried 10 cm under the surface in a glove, that is pretty easy. Instead, we bury the transceiver in a bigger target, like a big duffle. If we are feeling really ambitious, we use a dummy (you can make your own with an old set of coveralls). This let’s you really feel the difference between a probe strike on the ground and one on a soft target.

One good way to make your practice realistic is to bury the target in old avalanche debris. Just make sure there's no risk of avalanche if you do.

We always keep our gear with us (gloves, poles, pack, etc…) and practice with our pack on and all the tools we need. We split our time between searching as a solo rescuer and as a team with a leader. We learn by practicing with the same people we ride with and figure out who will likely do what in a scenario. Some people are just naturally the leader of the group, or the fastest shoveler, or the best rider. It’s good to know that going into a real scenario.

The whole scenario is different if you are moving up or down the slope so we try and practice doing both. Practicing a scenario first from the bottom and then from the top (or vice versa) is a great way to maximize a training day. This is especially true when we do our sled scenarios.

Practicing in realistic terrain can be hard to make happen but it will be the highest value scenario you do. Getting into character and really trying to visualize scene safety, high points, escape routes, and your mental map of the scene all help make it feel as real as possible. 

If we start far enough away that we don’t have a signal from the beginning, we get the added bonus of doing a signal search practice. It gives us a chance to flow through the whole progression: signal search, coarse search, and, finally, fine search. The Companion Rescue Card is a great reminder of the sequence of steps. 

As the season goes on and we get more familiar with the simple scenarios, we introduce more complexity to our practice sessions, such as multiple burials, deeper burials, and close burials. We start to intentionally introduce transceiver interference and practice problem solving so we can reduce the chance of it happening in real life. When it gets tricky or there are things that don’t work, these are direct learning moments. We debrief and we try to identify the problem without blame to see how we all can do better next time.

Most of all we make it fun. If you are the competitive type, time yourself and your friends and make it a race against the clock. Keep it light and practice often. Bury a beverage or a favorite chocolate bar along with the transceiver as a reward for digging up the target. Most importantly, make sure your partners practice with you—your life depends on them. 

How to add realism to your companion rescue practice so you're ready for the real thing.

Rescue Practice: Keeping it Real

In much of Western Canada, a 50 to 150 cm slab is sitting on top of a crust/facet combo which has produced some surprises over the last few days. Conditions are officially tricky and potentially high consequence. If you’re heading out, making conservative terrain choices and leaving a wider margin for error is essential, here are some strategies AvCan forecaster Josh Smith uses to manage persistent slabs:

I make more conservative terrain choices and leave myself way more margin for error in my decision making. I reduce the likelihood of triggering the layer of concern by avoiding classic trigger spots in the terrain, such as steep slopes, roll-overs, and spots where the snowpack is shallow or thin to thick.

I reduce the consequences of being wrong by sticking to smaller pieces of terrain that aren’t capable of creating large avalanches. I also avoid slopes with terrain traps such as cliffs, crevasses, and deep depressions where even a small avalanche can have deadly consequences. 

I find this easy to do for a few days, but when the problem persists for weeks, I find it takes a lot of discipline to not let my desire to push into bigger terrain get the best of me. However, in my experience, patience pays off when you nail that dream line in perfect conditions.

Want to really get into it?  Here is the Full Low Down: 

How did this persistent slab scenario develop? This problem was created by the atmospheric river event in early December that left a hard surface crust capping the snowpack. After the storm, a weak layer of facets (sugary snow crystals) began to develop above and below the crust. There’s now 50-150 cm above this interface. While there have only been a few avalanches reported on this layer, the ones that we’re seeing are concerning due to their wide propagations. This means, if you do hit the “sweet spot” on the wrong slope, it results in a large destructive avalanche that can connect smaller pieces of terrain.

Here’s why we are concerned. In many of the regions, the cohesive slab of snow on top of this layer has been building slowly; something we refer to as “incremental loading”. It seems to be coming into its own right now, it’s getting just enough cohesion to fail as a slab, and there have been a few different human triggered avalanches in the last few days across the province.  They’re sporadic, but they’re spooky avalanches in terrain that isn’t all that threatening at first glance.  

Here's an image of an avalanche a skier accidentally triggered in the Cariboo Region on Tuesday December 14:

It’s incredibly difficult, if not impossible, to predict exactly how much snow it will take to finally tip the balance and really bring this problem to life. Is it the next storm that overloads this weak layer, leading to numerous natural and human triggered avalanches? It might be. Or is it one of us moving through the terrain that becomes the proverbial “straw that breaks the camel’s back”?

Image of an avalanche a skier accidentally triggered in the Sea to Sky Region on Thursday December 16. Photo: Michael Cooperberg

The storm forecast to impact much of the province this weekend is looking like it's going to wallop the coast, and then dry out as it moves inland, producing more moderate snowfall amounts in the interior and Rockies.

Avalanche Nahatlatch area, South Coast Inland region Dec 14 2021

Video from the Nahatlatch area, South Coast Inland. Credit: Harrison Lake Heliskiing

You will see elevated danger for regions where significant snow is forecast, but the ratings may not look so bad across the board. However, it’s important to remember that even a moderate danger rating means: “large human-triggered avalanches are possible in isolated areas.” Danger ratings are helpful for getting an overview, but to get the whole picture, you’ve got to dig deeper than the danger rating– this is especially important when dealing with the kind of condition that currently exists.

The real “meat and potatoes” of an avalanche forecast are the avalanche problems. When we’re out in the mountains sledding or ski touring, avalanche problems are at the forefront of our minds. Here’s what we think about:

Where in the terrain are we likely to find them?

How big will the avalanche be if we do trigger it?

For example, when the danger is rated moderate and the only avalanche problem is a storm or wind slab, we treat the mountains very differently than when the danger is rated moderate and there is a persistent slab problem. Storm or wind slabs are way more predictable than persistent slabs. We have a lot more uncertainty about the snowpack when dealing with persistent slabs. This makes recognizing and managing or avoiding persistent slabs a much more complex challenge.

The only real option at times like this is to scale back and adopt a conservative approach.

As the next weather systems roll in, continue to watch the forecasts where we’ll keep you updated on how this situation is evolving.

Another view of the avalanche a skier accidentally triggered in the Sea to Sky Region on Thursday December 16. Photo: Ken Bibby

A persistent slab problem is here. How do we deal with it?

We’ve long known that transceiver signals can be affected by metallic and electronic items. In our increasingly wired world, where we head into the backcountry with phones, video cameras, satellite communication devices, and more, this subject has become more important. With this in mind, I did some homework. 

A transceiver search can be quite challenging. Make your life easier by eliminating potential sources of interference. 

First, I discovered that interference is generally described as being either “passive” or “active.” Passive interference blocks the transceiver’s signal, and it happens when the transceiver is too close to items made of metal or foil. I’ve often seen transceivers produce an error message or alert when someone was wearing it near or under a pocket that contained a candy bar with a foil wrapper or a metal water bottle (ok, truly, it was a whisky flask—but you get the idea). 

One of my most memorable experiences with passive interference involved a regular one-metre transceiver check that showed no problems, but at about 10 metres the signal completely disappeared. Eventually we determined there was a layer of heat-reflective foil in the person’s jacket. When they took off the jacket the problem disappeared. (Yes, we did find them another jacket, so they didn’t have to ski in their underwear).

Active interference disturbs the transceiver’s signal. This occurs when the transceiver is too close to devices that use electricity, carry an electrical current, or transmit or receive electronic signals. The result of active interference is like static on the radio or a pixelated TV picture. The signal is distorted, which makes the transmitted information hard to understand.

These days, we’re surrounded by items that can present active interference. Heated jackets, gloves, and socks all have wires carrying an electrical current. Add mobile phones, GPS units, and satellite-enabled communications devices to the list. And don’t forget when we link our devices using a wired connection (attaching headphones to our phone) or wirelessly (pairing a GPS unit or SOS device to our phone via Bluetooth). All of these and more are potential sources of interference.

Interference—both passive and active—affects a transceiver’s send and search modes. Mitigating interference is not complicated while you’re in send mode. Keep all sources of interference, passive and active, at least 20 cm away from your transceiver. I personally shoot for 30 – 40 cm. 

This means making some effort to ensure your transceiver stays in place, so it can’t get closer to any gear that might cause interference. This may require some modifications to your transceiver harness. I keep my transceiver on my right hip, in an inside pocket with a zipper closure. Anything I need ready access to, like my radio, goes in my top left jacket pocket. Electronics that don’t require quick access, like my GPS, SOS device, and phone, all go in the top pocket of my pack, on the left side. 

If you are shooting POV video, wear your camera on your helmet or use a stick. A chest harness is a no-go (where I ski a chest harness is useless anyway—all you see is white all the time). Jackets with a heat-reflective foil liner are also a no go. Be careful—sometimes the foil is between the jacket shell and liner so it may not be visible. Heated socks are probably okay but heated jackets are definitely not. Heated or foil-lined gloves should be avoided because the transceiver is in your hand when you’re searching. If you use these types of gloves, they need to be taken off and stowed away during a search, so you better have a back-up pair. 

When in search mode, you’ll need to increase the distance between your transceiver and sources of passive interference to 50 cm. This is not as big a deal as it might seem. Simply taking your transceiver out and holding it in front of you will likely be adequate. If you wear an electronic watch, you’ll need to take it off and store in your pack while searching. 

The electrical engineers I talked to were most concerned about active interference in search mode. There are so many types of devices operating on various frequencies, the experts I consulted felt there is no realistic way to test all those combinations and configurations to come up with a standard approach to solving this problem. 

The consensus advice was this: When it comes to active interference—items with an electrical current, or any type of signal like Wi-Fi, Bluetooth, GPS, or phone—the best approach is to turn these devices off when searching. Even when not in active use, many devices are actively searching for or receiving information, which can interfere with your transceiver. Even sleep mode, airplane mode, and other means of restricting functions does not guarantee your device is fully dormant, and interference remains possible. 

In practically all cases, when you turn off an active source of interference it then becomes a passive source of interference and needs to be kept 50 cm away from your transceiver in search mode. So, after you’ve turned everything off, stash them in your pack before you begin searching. Turn off your heated socks and remember that in the fine search stage, when your transceiver is near the ground (and your feet), be aware that you’re getting close to the wiring and batteries. 

Remember to turn off your heated socks so they don't cause interference during the fine search.

However, some electronics may be essential in some situations. You may want to use a phone or a radio to call for help or communicate with other rescuers. You’ll almost certainly want to send an SOS from your emergency messaging device, and you may need to provide information to the recipient of your SOS message. 

If you’re using a device to communicate while searching, the advice I got was to keep that device at least 25 metres away from the searching transceivers. In a best-case scenario, you would have enough people on scene to allow someone to move away from the search to handle any messaging. If that’s not possible and it’s essential you use a device, consider stopping your search, do what you need to do, then turn the device off and stash it before resuming your search.

Keep vehicles, snowmobiles, and other machinery at least 25 metres away from search areas. These are generally packed with electronics, have lots of electrical components, and are going to cause significant problems if they are too close, especially if they are running.

What’s essential and what’s not essential will vary from one situation to the next. In a place where there’s no cell coverage and you are out of range for two-way radio communications, mobile phones and radios may be non-essential and you’ll rely on your emergency satellite communications device. If you’re using your phone or two-way radio to coordinate an effective rescue and are getting help by these channels, then maybe your sat device is non-essential and can be turned off.

Interference commonly manifests as intermittent transceiver signals, distance indicators changing for no apparent reason, inconsistent directional arrow displays, and audible tones fluctuating even when you’re standing still. Ultimately, if you experience any of the above or other unusual transceiver behaviour, especially when in search mode, you should suspect interference and take steps to mitigate it. Personally, if I get any weirdness while searching, my first response will be to turn off EVERYTHING and stash it.

If all else fails, make sure you are fully familiar with micro-strip search patterns. If you’re having trouble locating a signal, micro-strip searching will resolve most situations, not only interference but also other issues like multiple transceivers buried in proximity. If you don’t know what a micro-strip search is, take a Companion Rescue Skills course.

Here are some common sources of interference:

Heat reflective clothing (jackets, gloves, mitts)

Magnets of any kind, including those used in closures for zipper flaps and pockets. 

Satellite communications devices: Satellite phones, GPS units, and SOS/emergency communications devices

Watches, especially GPS and smart watches

Heated clothing (jackets, mitts, gloves, socks)

Medical devices (pacemakers, insulin pumps, etc.)

Mitigating Avalanche Transceiver Interference

Avalanche hazard is declining in much of western Canada in the wake of the trilogy of atmospheric rivers that drenched the region, but new problems are developing in the snowpack. During the rather warm storm cycle, intense precipitation and strong to extreme winds drove a natural avalanche cycle and made decision-making easy. With avalanche danger high to extreme, most of us just stayed out of avalanche terrain. As temperatures cool and we get into a more seasonal weather pattern, avalanche hazard is decreasing but decision-making is going to become more challenging. 

Since the weather began to clear on Dec. 1, freezing levels have gradually fallen, the extreme southwest winds have diminished, and there has been a break in the precipitation. As a result, a crust has formed below 1,700 m in much of the mountains of western Canada, and as high as 2,400 m in some ranges (it averages about 2,000 m). More recently, the winds shifted to the west and then northwest, which has created unusual loading patterns and left us with a wind slab above the crust in some regions.

For those seeking good riding conditions, this will most likely mean trying to get up high to find dry snow. This is also where you’re most likely to find this combo of unusual wind loading above the crust. The fact that these slabs rest on the crust may allow them to remain sensitive to human triggering a bit longer than we’re used to. If triggered, they have the potential to run fast and far.

There are some serious objective hazards out there too. Many avalanche paths have hard, re-frozen debris in them. If there isn’t snow above the crust, a slip could result in a fall that is difficult if not impossible to arrest. Check out the video at the end of this post for an example of this hazard.

The complexity will grow as more snow arrives early this week. Observations are already coming in of surface hoar growing on the new crust below treeline in some locations, and facets on the crust in others. These are both dangerous combinations. In the near future, the supporting details in the forecasts will become invaluable as you manage the complex snowpack that is forming. 

Let's all remember it’s still early in the season and we’ve got a long way to go. For better or worse, this crust is going to be a player for the next few storms, at least. If you’re thinking about stepping out into more committing terrain, do it slowly as you gather more information about the bond between the crust and the new snow above it. As time passes and more observations come in, we'll learn more about the problem and how best to manage it.

Here's a fun video from our South Rockies Field Team as they were out "travelling" on the crust.

SoRo Crust

The backcountry is a changed landscape in the aftermath of the series of atmospheric rivers.

The River Has Run Dry

Welcome one and all to the 2021-22 avalanche forecasting season! Step right up!

As you read this, our home page will be brightened with the colours of danger ratings—and it isn’t a moment too soon. With snowpacks of varying heights and structures taking shape across western Canada, and headlines like ‘Atmospheric Onslaught’ leading the Mountain Weather Forecast, it’s time for all of us to get our heads into the avalanche game.

It's time to start checking the avalanche forecast. (Note: the current forecast is not pictured.) Photo: Jen Coulter

The first thing to know about our initial forecasts—and it’s probably clear in more than a few bulletin headlines—is that forecaster confidence is firmly in the low-to-moderate range. On the whole, our professional avalanche data stream is better described as a trickle. A few ski resorts are spinning their lifts, heli-skiing and cat-skiing operators are easing into their tenures, and professional guides are making their first forays into the field. Avalanche Canada field teams are about a week away from start-up, which is especially important to building a picture of the snowpack in the regions in which they operate: the North Rockies, South Rockies, Northwest BC, Vancouver Island, and Yukon.

Until all these operators are in full swing, our forecasters will be making the best of a limited data set. They’ll rate their confidence in their forecasts as either low, moderate, or high on the Details tab of each avalanche forecast, so be sure to check it out as you read the bulletin.

So, how do we manage risk and exposure to avalanche terrain in a low-confidence scenario? Here are five strategies:

1. Mellow slopes=better riding=less danger

Making conservative terrain choices is the safest option when there is limited information about the snowpack. This approach can also help avoid early-season injury. It’s usually the riders rushing on to steep features in the early season that find bone-jarring crusts, hidden sharks, and marginal sliding conditions. Seek out lower-angle terrain where snow has been filling in the cracks and gaps. You’ll be less likely to snag something lurking under the snow, and you’ll have minimized your exposure to avalanche terrain to boot.

Taking it easy on mellow slopes is a great early-season option. Photo: kflans.

This means watching for signs of instability, observing the bond of new snow to any old surfaces, scanning terrain for wind loading patterns, and thinking about how any weather changes you’re experiencing will affect avalanche conditions.

A savvy sledder’s snap of shooting cracks (a strong sign of instability) at Bullmoose in the North Rockies. Photo: Dave Mustang

If the snowpack is thin, lumpy, and perforated with bits and pieces of ground roughness like small trees, rocks, and alder, there’s a good chance the snow isn’t deep enough for avalanches. Once you start to see smooth snow cover that has overcome ground roughness, the threshold depth for avalanches has been achieved. That means it’s game on—especially as new snow accumulates on this surface. Note how this characteristic varies with elevation as you move through the mountains.

That thing I said in the last section about thin snowpacks and threshold depths? Toss it out as you approach the alpine. Many alpine slopes are plenty smooth with even the thinnest blanket of snow over them. In fact, some of the easiest places to trigger an avalanche right now are where the snowpack goes from thin to thick on steep alpine slopes. This week’s storm will do more to add consequence to this problem than it will to overcome it.

If you’ve had a chance to get out and check on conditions in your area, post your observations to the Mountain Information Network (MIN). This helps others in the community learn from your day in the mountains, and your avalanche forecaster will be stoked to have another piece of information to help them put together the conditions puzzle in your region. This is always a good thing!

A MIN contributor surveys the aftermath of an avalanche involvement in Glacier National Park on Nov. 22. Photo: OliD

A highly active weather pattern will increase snow depths and avalanche danger across western Canada this week. This doozy of a storm will make landfall on the BC coast on Wednesday and continue through to the weekend. That helps mitigate the uncertainty in the short term, as in most regions we’ll have good confidence that avalanche danger will spike with its onset. Check your local avalanche bulletin to see how this storm is expected to affect regional avalanche danger. 

Remember to ease into the mountains cautiously. It’s a long season, full of opportunities for adventure, so keep that in mind when you head out.

What you should know about avalanche forecasts early in the season.

Avalanche Forecasts are Here!

Everyone is aware of the serious effects of the 2021 wildfires in British Columbia and other parts of North America. Forests burned off, homes and businesses were lost, and entire communities were destroyed. We feel fortunate at Avalanche Canada that none of our staff or facilities were affected, and our thoughts are with those who suffered losses.

A wildfire burns a mountainside. Photo: Aleks Klassen. 

A less recognized effect of wildfires is the potential for increased debris flows. When fires are intense, vegetative cover burns and root systems are destroyed. This results in loss of soil stability on steep slopes. The removal of surface organics (duff and litter) means there’s less vegetative matter to absorb moisture. And in some cases, when fire conditions are right, hydrophobic soil is created, which prevents water from penetrating the surface. This forces water to run off in much greater volumes and much faster than normal. These factors can lead to more and bigger debris flow events.

This summer's wildfires destroying vegetation. Photo: Aleks Klassen.

Some of the factors that increase the chance of debris flows also increase the likelihood of avalanches. A loss of trees removes anchors that hold snow in place. Removal of undergrowth creates a smoother ground surface that is less able to keep snow in place. These lower threshold snow depths can result in more avalanches.

Slopes with less tree cover are more exposed to wind and sun, which may create a snowpack with more and different layers than before the fire. Sun crusts, wind crusts/slabs, and even surface hoar layers are much more common in the open areas and sparse trees found after a fire event. These kinds of layers are associated with different (and probably more) avalanche activity than may have been common pre-fire.

Avalanche terrain ratings have almost certainly been impacted in areas where fire has significantly altered vegetation cover on steep slopes. After a major burn, slopes will almost certainly warrant a higher Avalanche Terrain Exposure Scale (ATES) rating. Changes in ratings will not be reflected on existing maps unless an area is re-mapped to account for the altered ground cover.

An avalanche crown in an area of burned forest. Photo: Grant Helgeson. 

Here are some things to consider when in fire-affected avalanche terrain this winter:

When using tools like the Avaluator Trip Planner and Slope Evaluation card, which rely on ATES ratings as part of the decision making process, be aware that ATES ratings for areas that have burned since they were mapped may not be accurate.

Be wary when the snowpack contains free water in burned areas. Water can percolate right down to the base of the pack. If it encounters hydrophobic soil at the snow/ground interface, wet avalanches might be more likely than normal. Even worse, an already destructive wet avalanche might become even more dangerous if it mixes with a debris flow.

Sparse trees and burnt stumps may give a false sense of security on steep slopes. Surface hoar forms readily in these zones, and the snowpack may not be sufficiently anchored to prevent an avalanche when persistent slab conditions are present. Instead, snags may act as dangerous obstacles that could increase trauma if an avalanche were to occur.

Avalanche forecasts can’t address the challenges you might encounter when in wildfire affected areas this winter. Only you can recognize if an area has changed due to fire and assess if you should take additional precautions. Perhaps the most important thing in all this is to not take your traditional knowledge about the snowpack and avalanches for granted if you’re headed to a familiar spot and find it’s been burned since you were last there.

How wildfires affect the avalanche conditions

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