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

Wildfires and Avalanches

Boo to you from our crew! It’s that time of year again. The valleys have transformed into a gloomy shadow of their former selves while the sudden appearance of ghostly white mountain tops speaks to the enchantment of winter.

Taking care of your body might not be the first thing on your mind while hoovering up Halloween treats, but it’s definitely a mindset to take with you if you’re heading into avalanche terrain at this time of year. Info coming out of the mountains is still quite scarce and forecasts don’t start until November 25. This means you’ll need to make your own observations and assess conditions as part of your decision-making process. The Dangerator could be useful here but leave the Ouija board at home! You can also check out our Early Season Conditions page for a discussion of the different types of mountain hazards that start to reanimate at this time of year.

Coverage steadily improving In the Mountains of Madness (aka Brandywine Valley, Sea to Sky region). Photo: Jack Casey.

Be sure to do a thorough equipment check when it’s time to swap your Squid Game costume for backcountry gear. You’ll want to make sure your transceiver has new batteries and up-to-date firmware. Also check your probe and shovel are working properly, and, if you have one, charge up your avalanche airbag pack. Hopefully you kept your ski/splitboard, snowshoe, and sled maintenance up over the summer so that you don’t get stranded on your way home through those ominous woods on your first day of the season.

Hypnotic powder 8's flank an Sa (spider accidental) in Brandywine, demonstrating there's definitely enough snow to slide out there. Photo: Reece A.

Just like plotting out the best route for trick-or-treating in your neighbourhood, this is a time to think carefully about where you travel in the mountains and what terrain you want to pay a visit to. With this in mind, jumping on the first big, steep slope you see might not be the best idea and might give you more of a scare than you’re after. There’s a lot of winter ahead and easing into terrain gradually, evaluating slopes for the potential for avalanches will help to ensure you’re able to enjoy it fully rather than nursing an early season injury, or worse. Heading out to some familiar haunts also probably makes more sense than a long-distance journey into the heart of darkness as daylight hours keep whittling away toward solstice.

Field tech Jack O. slashing some low angle meadows to avoid murdering an A-arm in October. Photo: Nicole Matei.

Depending where you are, clearing skies and fresh snow in the mountains could lend well to an exploratory mission this weekend. If you decide to go and check things out for yourself, keep the ideas from this blog in mind and be sure to share your observations with the community on the Mountain Information Network. Scary Halloween crust? Wickedly white slopes reaching threshold depth for avalanches? Ski bases gored by sharks lurking just under the surface? Let us know!

How to avoid being spooked in the mountains this Halloween

Hallo-winter

Avalanche Canada is about to wrap up the forecasting season and the last bulletins will be published on April 23. The sole exception is the Yukon, where we will continue to forecast until May 7. As our forecasting team looks back on the season, we feel very thankful for what we were able to accomplish, in large part due to the amount of information that we received from all of you. We had great uncertainty on our data inputs with limited professional operations working, but a big chunk of you stepped up to provide invaluable information for us to prepare high-quality daily bulletins. Below are some of the statistics from this season. A big THANK YOU from all of us at Avalanche Canada.

2,600,000 forecast views at avalanche.ca and on the app

200,000 views of the Mountain Weather Forecast

Up to 101 MINs in one day (see graph below for daily distribution and comparison with last year)

Daily MIN submissions, showing a big increase this season compared to last season

This season, you’ve also helped to make our social media channels successful with all of your interactions and shares. With your support, we were able to reach 481,000 people on Facebook and gain 12,400 new Instagram followers. Thank you for all of your support in getting our messaging to more people.

As well as the likes and follows, we’ve also received lots of messages from people with ideas, information, and support during this tricky season. Thank you to everyone who took the time to get in touch. 

Up to almost 900 viewers in a single webinar, with a total of 5,400 viewers

Again, we thank you for your observations and we hope to see even more next season. Until then, enjoy the spring and summer and we’re already looking forward to starting back up next fall!

- Mike and the entire team at Avalanche Canada

We’ll leave you with a small selection of some of the photos from the MIN of the week winners from the season.

Thanks for a great winter

Around this time of year avalanche forecasts switch from rating danger by elevation band to rating danger by time of day. During winter months avalanche conditions are largely driven by snowpack layers, which vary dramatically across the terrain. But during spring they are largely driven by snowpack temperatures, which vary dramatically over time. So in the winter we communicate the danger with a single rating per elevation band that best describes the severity of the conditions in that type of terrain.

But eventually conditions fluctuate so much throughout the day it becomes more effective to represent this with the spring conditions icon.

This icon suggests avalanche hazards can largely be managed by paying attention to daytime warming and surface conditions.

But during the transition from winter to spring, additional strategies may be needed to avoid avalanche hazards. The complex layers in the snow can take prolonged periods of warm weather to consolidate into a simple and predictable spring snowpack. So during these current warm conditions there may be additional problems in the snowpack that require more than simply monitoring daytime warming.

Our forecasts largely rely on sharing professional and recreational field observations, especially avalanche observations that provide direct evidence of the conditions. Right now we are still receiving sufficient field observations to highlight unique problems in different regions. These are highlighted in the Problems and Details section of the forecast, and influence the danger ratings. Eventually as information sources dry up and the snowpack layering becomes simpler, we decide the spring conditions icon provides the best possible starting point for planning a day in the backcountry.

During this current warm weather we are using danger ratings to show the dominant overall conditions across the region. This rating is what we think is most useful for planning your day. While this is largely being influenced by daytime warming, it may also factor in additional avalanche problems and localized weather conditions. Other sections of the forecast provide context about when, where, and how the ratings should be applied.

We will likely start transitioning to the spring conditions icon on a region by region basis next week, depending on how the snowpack responds to the current warming. All other parts of the forecast including the headline, avalanche problems, and details will be updated daily until April 23 (and until May 7 for the Yukon).

After April 23 the forecasts will provide a spring conditions statement that highlights one of the four common scenarios in our Spring forecasting guide. This will continue for a few weeks until we switch to an off-season summer message.

Regardless of the time of year you can help your fellow backcountry travelers as well as the quality of the forecasts by sharing observations on the Mountain Information Network!

Communicating spring conditions

Spring is certainly in the air, and with it comes change to the snowpack. With warm air and generally clear skies, the snowpack weakens as it reaches its melting point (0°C). Resulting avalanche activity largely depends on the layering, or lack thereof, in the snowpack. If the snowpack is deep and strong, generally loose wet avalanches are the main concern. If the snowpack has weak layers within it, destructive, full-path avalanches can result. 

A full-path avalanche that travelled well into the valley.

Predicting avalanche activity when it comes to warming can be both straight-forward and tricky.

The relatively easy activity to predict is loose wet avalanches. As mild air temperature and solar input warms and melts the snow surface, natural avalanches will occur, often initiating near rocks or trees. The consequence of such avalanches is typically low, with the primary concern being if you are caught above a terrain trap (cliffs, gully, etc.).

Loose wet avalanche activity during daytime warming.

Slab avalanches are more difficult to predict.  It often takes multiple days of warm air temperatures for deeper layers in the snowpack to experience the influence of the warming, making it difficult to predict which day (if any) slab avalanches may occur. The concern is that resulting avalanches are often very large and destructive; they could even start high in the mountains and terminate in the valleys. Needless to say, you do not want to be near any of these when they occur.

Slab avalanche triggered by snowpack warming.

Cornices are very large at this time of year but predicting what day they may release is almost impossible. Cornices should always be treated as suspect, particularly during periods of mild air temperature and sunny skies. A person on top of a cornice that fails could fall down the mountain side and a cornice that falls from above could impact you, like being hit by a train.

Large cornices line mountain ridges at this time of year, which are more likely to fail during extended warm periods.

Large slab avalanche activity could occur in any of the forecasting regions, but we believe they are most likely to occur in the following regions, where buried weak layers are more likely to be found:

Although Avalanche Canada does not forecast for the National Parks or Kananaskis Country, these regions will see a similar pattern with the coming warm weather.

Widespread avalanche activity during daytime warming.

With the uncertainty of timing and size of avalanche activity, we offer the following guidance to play safe in the mountains during this warming trend:

Start your day early and end your day early. Avalanche activity will be less likely when the snowpack is coolest during the night and early morning, and most likely during peak daytime warming.

Watch for preliminary signs of daytime warming, such as a moist or wet snow surface, snow falling from trees, or snow falling from steep terrain and pinwheeling down the slope. This is most likely to first occur on sun-exposed slopes.

Be particularly cautious if there is no overnight freeze (i.e., air temperature stays above 0°C even during the night). This means that warming can push even deeper in the snowpack, increasing the likelihood of avalanche activity.

If you are in an area where deeper weak layers may be present, do your best to avoid large, high consequence terrain during periods of daytime warming. 

Since avalanches could release full path, you will want to avoid travelling through the runout zones of avalanche paths, particularly during the middle of the day. This includes runout zones that are snow-free, as large avalanches from above could travel far into the valleys.

Avoid travelling along the edges of ridgelines or on slopes beneath cornices. If you are on a ridge and can’t see the slopes beneath you, assume that a cornice is present and stay well back. Cornices themselves can kill people and their release can also trigger slabs on the slopes below.

Follow the avalanche bulletin for your region, which will be updated daily until April 23 (and later for the Yukon).

Spring riding can be some of the best of the year; let’s all enjoy it safely.

As the tulips rise

Some years, by April we’re shredding corn snow in sunglasses and a t-shirt. Our bodies are already accustomed to waking in the wee hours to bag all those steep lines we’ve been eyeing up all season. Managing avalanche danger is reduced to meeting back at the car by noon for beverages and listening to the sun bring down big wet slides. 

This version of spring skiing only comes around once the snowpack has experienced sufficient warming and cooling cycling to consolidate deeper layers and metamorphize surface crystals into corn. Avalanche danger then fluctuates predictably between high and low following the rhythm of diurnal cycles where the sun warms the snowpack up in the daytime and freezes it solid overnight. As a result, we can ride anywhere we want as long as we’re out of there before it gets too warm and avalanche danger ramps up.

Managing avalanche danger can be pretty straight forward when directly linked to wide temperature fluctuations between day and night.

This year we find ourselves at the beginning of April with upper elevations still in full winter mode. This means that managing avalanche danger isn’t yet so simple. Pow skiing has been great but it comes with surface instabilities like storm and wind slabs, as dry snow is prone to destabilizing changes brought on by temperature, sun and wind. Deeply buried weak layers also remain a question. Without deeply penetrating warming cycles, these structures remain intact. When those initial warming cycles do arrive, there will be a lot of uncertainty around if, where, and when we might see very large and destructive deep persistent slab avalanches.

It’s still the season for storm slabs .They can become increasingly sensitive to triggering with rapidly changing springtime weather conditions. Photo from a MIN submission on the Central Duffey March 30.

How can we manage this? Just keep up all the good habits you’ve been practicing all winter! Check the bulletin not just for avalanche danger but also the types of avalanche problems that drive the danger. Knowing the avalanche problems is key to helping determine how to choose what terrain to travel in and what to avoid. For example, wind slabs can be most likely found in lee terrain features at upper elevations. Maybe you find some good snow in a sheltered area lower down and avoid the problem altogether. Maybe you decide you can identify and manage wind slabs with careful route selection or ski cutting. Carefully consider the problem, its distribution, likelihood and consequences and your mitigation options.

 Keep your eyes and ears open for changing conditions. Spring weather can pounce on us at any time. Convective squalls can bring sudden and heavy localized snowfall, temperatures can rise quickly in the day and the sun packs a punch when it comes out. When it properly warms up to mountaintop for the first time, we’ll need to dial it back while the snowpack adjusts. We still have a bit more tiptoeing to do through these dynamic times, but remember, these processes that are destabilizing in the short term will ultimately result in that bomber spring snowpack we’ve been dreaming of.

Spring is Coming...

Every year around this time we start to think about the impacts of warming on the snowpack. Historically, March is the deadliest month for avalanche fatalities, likely due to a combination of snowpack and human factors. The first big warm up can shake things up, especially when we have cold snowpacks with persistent weak layers like the ones currently in play throughout western Canada. In addition to tricky avalanche conditions, longer and warmer days can lead to “blue sky syndrome” where we potentially underestimate risk and let our guards down.

The incoming weather has caught the attention of the AvCan forecasting team. As the week progresses we will see the first significant warm up of the season, in some regions accompanied with moderate to heavy precipitation. The timing, severity, and spatial extent are not yet fully certain, but from a few days out it seems like the greatest warming will be in southeastern BC and southern Alberta. That said, warming will be a concern in all regions - especially those with lingering persistent weak layers.

In the coming days we will closely examine weather forecasts, and any specific concerns will be reflected in our daily avalanche forecasts. But there are some overarching themes to think about this time of year regardless of your region or which day you are considering travelling into the backcountry:

Reduce your exposure to avalanche terrain when the temperature is rising rapidly. Be even more cautious if temperatures are above zero.

Avoid travelling on or under slopes that are getting hit by the sun. This includes keeping an eye on slopes above you, especially in the morning when upper elevations get sun much earlier than down low near valley bottom. 

The importance of aspect becomes more pronounced. South-facing slopes are more susceptible to the impacts of warming, while north-facing slopes remain colder.

Timing is increasingly important; start early when it’s cool and end early before it gets too warm.

Be mindful of overhead avalanche terrain; avalanches are more likely to run to the end of their paths this time of year.

Small avalanches or cornice falls have the potential to trigger large avalanches when there is a persistent or deep persistent slab avalanche problem

Use the power of group decisions. Giving everyone a voice helps groups to make better, safer decisions. Speak up if you’re uncomfortable, or you think there’s a better option that might just require a little more effort.

Sudden changes to the weather are forecast in the coming week. Expect this to complicate avalanche conditions...

Time to consider warming

This weekend’s storm will bring some long awaited fresh snow, but the past few weeks of cold dry weather has left us with some tricky avalanche conditions. Most regions in the interior have been dealing with persistent slab and/or wind slab avalanche problems that have caught people by surprise - producing large avalanches in atypical types of terrain.

It looks like there may not be enough snow for HIGH danger and a big cycle of natural avalanches, but with these tricky problems even subtle changes like warming temperatures or a bit of wind-drifted snow could push the snowpack past it’s tipping point.

These problems come with many uncertainties. Rather than trying to outsmart them and push into precarious terrain, it’s better to just stay disciplined with conservative terrain choices. Your local forecast will point you in the right direction...

The following human triggered avalanches in the Cariboos and Lizard Range from Feb 17 show large avalanches are easy to trigger across many interior ranges. New snow, wind and rising temperatures this weekend will only make things worse.

Thanks for the many great observations submitted on the Mountain Information Network! Stay safe in the backcountry this weekend.

Changing weather may tip the scales in the interior mountains of western Canada

Danger rising in the interior

Looking ahead to this weekend, particularly on Sunday, February 21, all signs point to dangerous avalanche conditions for BC’s coastal mountains. If you’re planning a trip into the backcountry during this time, please lower your expectations, select safe, lower angled terrain not exposed to avalanche paths from above and watch for worsening conditions as the storm progresses.

During the extended dry period we’re just coming out of, cold temperatures promoted facet growth near the surface of the snowpack. There have also been reports of surface hoar growth, including this one from the North Shore and this one from near Shames. These weakly-bonded crystals are now being buried by new snow generating a weak layer in the snowpack.

Towards the end of this week and through the weekend, storm snow amounts will build with successive snowfalls before reaching a crescendo on Sunday. On Sunday, it looks like we’ll see a triple whammy of weather inputs: significant amounts of new snow, rising temperatures and wind. All adding further to the building weight of snow sitting on the weak layer.

Higher snow areas, such as (but not limited to) the North Shore mountains of Vancouver, western sections of the Sea-to-Sky, the Coquihalla, Shames near Terrace, and areas near Kittimat will almost certainly see natural avalanche cycles. While the danger in these areas should appear fairly obvious, users should still factor in the influence of the weak layer, which will make avalanches very easy to trigger and is likely to increase how far they run and how wide they propagate. Unless you have professional-level avalanche training, this could be a time to stick to the safety of in-bounds ski areas or ride sleds on groomed trails and meadows.

Avalanches have already been reported from coastal areas, such as this one from Tim Jones Peak. These are expected to increase in size and frequency with incoming storms this weekend. MIN photo: Scott Shiggy Mackay

Areas with less snow may see fewer natural avalanches, but conditions will still be ripe for human triggering. In these areas it might not be so obvious that the world is falling down, but I suspect avalanches will be easily triggered on steep slopes in many areas, including steep openings in the trees, gully sidewalls, slopes below cliff lines, as well as the usual areas in exposed high elevation terrain.

Adding to the complexity is a recent 180 degree shift in the wind. Old wind slabs due to arctic outflow winds primarily formed on westerly aspects, while new wind slabs are forming on north and east aspects from strong southwesterlies. Since the old wind slabs were laid down over cold, facetted snow, they are likely to remain triggerable for longer than usual.

A final concern: there’s a small but real chance of a step-down to a deeper persistent weak layer in some areas – predominately close to the US border and/or in lower snowpack zones. A release like this could cause a very large avalanche. The most likely place for something like this to occur are areas such as the east side of the Duffey, Allison Pass and possibly the Chilcotins (although we have very little info to confirm this last suspicion).

Once again, the key to staying safe is to stick to simple, low angled terrain that is not threatened by avalanches from above. Save steeper lines and bigger objectives for times when conditions are significantly better than they are right now.

New snow, rising temperatures, and an old, cold weak interface spell trouble

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