A crust buried mid-storm produced reactive conditions on Feb. 2 in Vancouver's North Shore mountains. MIN report from brento.

Last week we published a forecaster blog about shifting our mindset and stepping back as stormy conditions brought a sharp rise in avalanche danger. Widespread weak layers of surface hoar, facets, and hard crusts are now buried around 30 to 60 cm deep in the interior and up to 80 cm deep on the coast.   

As we return to cold and dry conditions, avalanche danger will likely remain elevated due to these buried layers. Maintaining a conservative mindset is key as these challenging conditions continue.

The Mountain Information Network (MIN) lit up over the weekend as people headed into the backcountry–thanks to everyone who posted! These observations help our forecasters and other recreationists. Most reported obvious signs of instability, even in conservative terrain. Several observers even noted slab avalanches on lower-angle slopes, around 26 degrees, which is typical of buried weak layers like surface hoar and facets. 

Storm snow takes longer to stabilize and weak layers are preserved in cold temperatures, so it’s time to embrace simple or non-avalanche terrain depending on your local avalanche forecast. Stick to low-angle or densely forested areas and look for options to reduce your exposure to avalanche terrain. While natural activity will likely decrease over the coming days, human triggering of avalanches will remain a concern for some time.

Here’s a reminder of some key signs of instability to watch out for: 

Remotely-triggered avalanches, often triggered from flatter terrain adjacent to a slope, e.g., ridge crests, benches, or areas below steep slopes.

Whumpfing, which is the collapse of a buried weak layer. It is often associated with a distinct “whumpf” sound. 

Shooting cracks in the snow that propagate away from you.

These all are red flags of an unstable snowpack that’s primed for triggering avalanches. Think of it as free advice from the snowpack itself—time to step back and reassess your plan.

Here are some recent MIN images to highlight some avalanches, observations, and signs of instability from around BC. 

This rider-triggered slab occurred on a 26 degree slope on Feb. 2, near Terrace. MIN report from gordweary.

Extensive cracking within the storm snow near Nelson on Feb. 1. MIN report from c.dierker.

This size 2.5 slab was remotely triggered near Pemberton on Feb. 1. MIN report from willvg7.

This slab was remotely triggered by riders as they were descending near Squamish on Feb. 1. MIN report from christieimages155.

A skier remote observed near near McGregor on Feb. 2. The group also had an avalanche incident that they highlight in the MIN. MIN report from ben-hawkins. 

When the snowpack is giving you free advice, take it

Keeping a Conservative Mindset

After a lengthy period of low avalanche danger for the southern half of western Canada, conditions are changing and it is now time to shift our mindset in the backcountry. Many regions will undergo a major increase in avalanche danger as stormy weather returns. The past three weeks of dry conditions formed layers that new snow won’t bond with. As new snow accumulates and forms slabs over these layers, we expect large and dangerous avalanches to be triggered both naturally and by humans. These avalanches are likely to propagate widely across slopes.

Weak surface hoar crystals grew on the snow surface over the past few weeks in many regions, which new snow won’t bond well to (Photo from Hyland Backcountry in the North Rockies).

What this means is that we all have to adapt our mindset and step back. Here are some travel tips to help:

Sticking to dense forests or slopes shallower than 25 degrees without overhead hazard is the best way to stay safe.

Dial back your terrain choices and even avoid avalanche terrain altogether as new snow accumulates. 

Stay away from terrain traps, such as cliffs and gullies.

Assess for conditions as you travel, looking for signs of instability: recent avalanches, whumpfing, and shooting cracks.

Consider that you could trigger an avalanche from a safe spot that releases on adjacent or overhead steeper slopes (remote trigger). 

Always be aware of what is overhead and if there are others around you.

Stay disciplined and don’t let powder fever lure you into terrain capable of  producing large avalanches.

Keep in mind that deeper slabs will likely be found in wind-exposed terrain, which means larger avalanches if triggered.

Ensure that each member of your group is engaged in disciplined terrain selection.

Travel one at a time when exposed to avalanche terrain and regroup in safe spots well away from overhead hazard.

We all want to enjoy the snow and come home safe at the end of the day. Remembering to follow these travel tips will help make sure that happens.

An avalanche that propagated widely in northwest B.C., providing an example of what avalanches may look like as new slabs form in the southern half of Western Canada.

Shifting Your Mindset

Whether you're a seasoned professional or a recreationist, building a strong mental model of the current conditions is essential for making informed decisions in avalanche terrain. Professionals returning after time away or joining a new operation start by gathering and reviewing critical information during shift handovers. This includes snowpack analyses, significant avalanche observations, layers of concern, and areas of uncertainty. Beyond collecting data, they assess the weight of each piece of information and how it shapes the bigger picture, ensuring sound decision-making in high-pressure environments.

Recreationists follow a similar process when they follow the Daily Process. Reviewing past and current weather data, analyzing the avalanche forecast in detail, and consulting MIN posts or local social media are key steps. Recording this information in a field book is a helpful practice, especially when internet access is limited, as it allows you to track critical factors throughout your trip. Together, these strategies form the foundation for safer and more effective decision-making in the backcountry.

Observations are an essential part of a strong mental model.

How to Use Your Mental Model in the Field

Once you’ve established a baseline mental model, you’ll need to maintain and strengthen it. Remember in constantly changing and dynamic environments, your mental model becomes stale unless you are continually updating it. This is the basis of situational awareness. 

A remotely-triggered, deep persistent slab avalanche in the North Rockies. A good reminder of the consequences of our decision making.

Let’s take a look at a simple example and some strategies we could use to maintain and strengthen our mental model: the sun unexpectedly emerges and is rapidly warming the air and snow surface. 

This information may well change the way we plan to move through the mountains. Let’s break down how we might need to update our mental model. 

We’ll start by thinking about what clues you might have noticed to tell you it was getting warm.

The surface of the snow becoming sticky and heavy.

Snow beginning to fall from trees, or small snowballs or pinwheels are starting to roll off rocks. 

Next we need to think about this information is telling you about the state of the snowpack.

The surface of the snow is changing rapidly. 

Small loose wet avalanches may now be possible.

In bigger terrain above you, the loose and dry snow may be rapidly settling into a slab. 

If there are deeper snowpack instabilities, they may begin to wake up.

All of these hints and clues tell us that we need to make changes to our mental model. We are no longer travelling in the same conditions we set out in, and we need to make sure we’re adapting. Ask yourself:

You’ve made an assessment that the snowpack conditions and weather are changing. Is your original route plan still appropriate for these changes?

Does sticking to your plan increase the risk outside of your acceptable range?

If the original route no longer works in the new conditions, it’s time to consider alternatives.

When we don’t work to maintain good situational awareness, our decision-making is often influenced by biases that can lead us into heuristic traps that undermine our careful planning. The first step in addressing these biases is being mindful and aware of their presence. While this blog doesn't detail these factors, understanding them is a fundamental aspect of avalanche safety training. 

As we move through the terrain, here are some key factors we need to keep in mind and work into our dynamic mental model.

Terrain: Identify terrain features, overhead hazards, safe areas, and terrain traps. 

Snowpack: Be aware of rapid snowpack changes, such as heavy snowfall, warming temperatures, or wind transportation of snow. 

Weather: Stay informed about the forecast and keep a sharp eye on changing conditions. If the weather deviates from the forecasted conditions, you’ll need to think about whether the avalanche danger might have changed too. 

Team Communication: Keep checking in with your group. Make sure everyone is on the same page about what you’re doing, why you’re there, and whether any of this has changed during the trip.

Severity: Make sure you’re considering what the consequences of an error might be. Has it changed during the day? What happens if you’re wrong?

A very large loose wet avalanche cycle late in the season North Coast, consequences from being caught in something like this could be severe.

It doesn't happen in the field, but it’s a key step keeping situational awareness skills sharp. After your trip, take the time to reflect and analyze your decisions. Debrief as a group and ask questions like:

Are there times where you think you might have been lucky?

What could you do differently next time? 

Answering these kinds of questions can improve your mindset and make your next adventure that much better. 

If you’d like to learn more about the Daily Process, you can find it here: https://avysavvy.avalanche.ca/en-ca/the-daily-process 

For a more detailed look at heuristic traps, check out this paper by I McCammon: https://arc.lib.montana.edu/snow-science/objects/issw-2002-244-251.pdf 

Heads Up! How to Maintain Situational Awareness During Winter Adventures

After several winters of low snowpacks and challenging avalanche conditions, this season has started with a refreshing return to "average." How average? As of December 15, the BC River Forecast Centre reported that the provincial snow depth was 102% of normal—about as typical as it gets!

Basin snow water index from the BC River Forecast Centre’s Snow Conditions Commentary for December 15.

November brought steady storms, building a solid snowpack without many notable weak layers or crusts. Most regions now have enough snow at treeline for great recreation: around 150 cm in the Coast and Columbias, and 100 cm in the Rockies.

Early December brought a dry spell, creating a mix of layers like surface hoar, rain crusts, and sun crusts. These layers can become problematic when buried, and while some avalanches have occurred on them, the issues seem sparse and likely short-lived in most areas. Recent activity has been most notable in BC’s southern Interior, particularly the southern Selkirks. Northeast of Pemberton is also suspect.

Webcams showing 25 to 50 cm of new snow on December 18.

December looks set to end with a bang. A storm on December 18 brought 25 to 50 cm of snow to southern BC and Alberta. And the action isn’t over yet—several frontal systems are lined up to bring more snow in the coming week.

The 500 mb forecast from the Mountain Weather Forecast shows a parade of storms hitting western Canada for the next week.

What to expect in the coming week? Avalanche danger will rise and fall with each storm as new snow and wind build reactive slabs. During storms, choose more conservative terrain and avoid steep, exposed areas. Afterward, start on low-angle slopes that are too small to produce large avalanches to assess the snowpack before considering venturing into steeper terrain.

What about the weak layers? In some regions, uncertainty remains about how long the early December weak layers will persist and which types of terrain will be most affected. Check your local forecast and if a persistent slab avalanche problem is listed, take a more conservative approach.

We’ll see what the rest of the season brings, but for now, we’ll gladly take an average snowpack without many significant weak layers. Wishing you a fun and safe holiday season!

A Refreshing Start to Winter

Daily avalanche forecasts are about to start for the season and winter backcountry recreationists are already getting into the mountains. 

AvCan team hard at work preparing for the first forecasts.

Travel is still a bit rugged down low, but as you gain elevation, you’ll find that there are fewer ground obstacles impeding your travel and the snowpack is likely above the threshold depth for avalanches. In many places, this transition is now somewhere below treeline and several Mountain Information Network (MIN) users across the province have already reported human-triggered avalanches.

Nov 18 Harvey Pass, southeast of Fernie Photo: MIN user DYLANSIGGERS

Nov 18 The Gorge, west of Revelstoke. Photo: anonymous MIN user

A bomb cyclone is currently lingering off the southwest coast of BC. This weather phenomenon is different from a run-of-the-mill storm because the atmospheric pressure in the center of the low drops very rapidly. This intensifies stormy weather driven by the low pressure system. We have already seen the effects of this on Vancouver Island and the south coast, with high winds and heavy precipitation. Coastal areas further north of the low are experiencing amplified outflow winds. The extreme weather conditions have not spread into the interior of the province. 

As the bomb cyclone weakens and shifts west, the intensity of the storm will decrease, but stormy weather is expected to continue for southern BC into the weekend. It’s likely we’ll see storm and wind slab avalanche problems for most avalanche forecasts over the weekend.

Bomb Cyclone moving west. Source: Mountain Weather Forecast

In parts of the interior mountain ranges that have seen less snowfall and cooler temperatures, a frozen crust buried in November is likely to be coupled with weak layers like facets or surface hoar. This is the case in some of the avalanches already reported, and the forecasted weather is not likely to improve avalanche conditions for these places.

Nov 17th Shovelnose, west of Whistler. Photo: MIN user KYLE_G1

Nov 16 West of Tumbler Ridge, North Rockies. Photo: MIN user DAVE

As you get a handle on avalanche conditions and get your winter legs under you, it’s looking like it will be a good time to start with small, mellow slopes where buried hazards like stumps, rocks, creeks, and larger terrain traps are easy to spot and avoid. As always, it will be important to check your local avalanche forecast and MINs in your area before heading out this weekend. The changing weather and setup of the snowpack mean that conditions could change quickly, so it’s important to get the most up to date information. The first daily forecast for Friday, November 22 will be published on the evening of the 21st.

Nov 13th Mt. Harvey, northeast of Smithers. Photo: MIN user HYLAND BACKCOUNTRY

Any Fallout From The ‘BOMB’?

Your guide to interpreting meteograms and interpreting them into your planning process. 

Meteograms are weather forecast diagrams created by Environment and Climate Change Canada (ECCC). As public avalanche forecasters, we use these on a daily basis as part of our forecasting workflow. They are a highly valuable and freely available resource that you too can incorporate into your daily process. You can find them on our website in the weather section. 

Although they can seem overwhelming, but once you learn how to read them, they're full of helpful information.

There are three choices of model you can use in your meteograms, which you can select using the drop down on the top left of the screen. They are the HRDPS, RDPS, and GDPS. We use each model for slightly different purposes. 

HRDPS (High Resolution Deterministic Prediction System)

This is a short-range and high-resolution model. It gives a prediction for 48 hours in the future across a 2.5 km square area. Usually, this model is the most accurate for short-term weather forecasting and often best reflects the mountain environment.

RDPS (Regional Deterministic Prediction System)

This is a medium-range and mid-resolution model. It predicts 84 hours into the future for a 10 km square area. This model doesn't account as well for mountainous terrain, but it is very helpful for spotting trends in the weather forecasts. 

GDPS (Global Deterministic Prediction System)

This is a long-range and low-resolution model. It predicts 10 days into the future for a 15 km square area. Due to the long term nature of this forecast, it may be less accurate in the short-term. We mainly use this for long-term planning. 

The meteograms are issued 4 times a day. They use Zulu time, which is a standardized time zone. For our purposes, we don't need to worry too much about Zulu time—we're just going to use the most recent one. 

We can choose between point meteograms or group meteograms. Point meteograms provide a forecast for one specific location and group meteograms summarize the information for a wider region and forecasts based on that.

A group meteogram can help us to understand the regional extent of the weather, pick out trends, or find hot spots for snowfall, wind, temperatures, etc. A point meteogram is going to zoom in on one specific area and give you an idea of the weather forecast for that particular area.

There are also (SNL/PT) versions of point and group meteograms that provide additional information about snow level and precipitation type. While this can be useful, the additional information sometimes makes it more difficult to see trends.

In the below example, the red lines show the freezing level and the blue line shows the expected snow line. Typically, we expect the rain-snow line to be 100 m below this line for weak precipitation and up to 300 m below during strong storms. The panels in this type of meteogram also gives you the precipitation types:

At first glance, this is a lot of information to process in one diagram! Let's break it down and start with the top panels.

This will tell you the location, with GPS coordinates, typical treeline elevation for that area, and the model grid point elevation. It will also give you the date and the model run. 

The green shading is telling us the relative humidity at different elevations. Dark green means high relative humidity, white is low. The black lines are humidity contours. As a rough rule of thumb, 80% relative humidity means it will be cloudy, 100% means precipitation, and the white areas suggest clear skies.

The chart also tells us about expected winds. The black wind barbs show the wind speed and direction at different elevations.

The barbs point in the direction the wind is expected to come from. You can also use the next panel down to learn about wind speeds at 2,000 m and 3,000 m elevations. The top panel is usually more accurate for learning about wind where you will be recreating though. 

The dashed red lines show the air temperature at different elevations (shown on the vertical access). 

The solid yellow line indicates the typical treeline elevation in that area. The dashed yellow line is the model grid point elevation, this means there is no data below that elevation. 

The bold red line indicates the freezing level. 

Let's skip down to the cloud cover panel. 

The blue line here shows the percentage of cloud cover. You can use his with the relative humidity data to get an idea of cloud heights and layers. 

The red line is shortwave radiation. This basically means how strong the sun is expected to be. We measure this in watts per meter squared. The influence this will have on the snowpack depend so on the surface snow conditions, but we generally consider anything more than 400 W/m as likely to have a strong impact on sun-exposed slopes. 

The next panel gives us information about the air temperature. Although this information shows us the difference between the air temperature (red line) and the dew point (blue), most meteograms are too low to be helpful for mountain forecasting. Often the first panel is more helpful for our planning.

This panel gives us the 12 hours QPF (qualitative precipitation forecast). It tells us how much snow or rain we're expecting and we measure it in millimetres. The red numbers show minimum, average, and maximum QPF for the 12-hour period between 4 AM to 4 PM (or 6Z and 18Z!) and 4 PM to 4 AM.

When we're dealing with snow, the amount of precipitation doesn't always result in a uniform amount of snow. To work out how much snow to expect from each millimetre of precipitation, we use the snow to liquid ratio (SLR). SLR is linked to temperature, colder air tends to produce higher SLR (15:1 or 20:1) and give us lighter, fluffy powder snow. Warmer temperatures usually mean a lower SLR (7:1 or 5:1) and denser snow, which is excellent for making snowballs.

I consider the world of weather forecasting to be a bit of a dark art. Meteorologists are literally trying to pin down a moving target to determine the exact track, timing, and intensity of a frontal system. It's essential that you verify the weather conditions in the field, in the same way that you are verifying the snowpack, because the two are very deeply related. 

There are so many fascinating things to learn about the complex and dynamic phenomenon of mountain weather. In the winter, reading the Mountain Weather Forecast on a daily basis is the perfect place to start to build a foundational knowledge of weather and start your trip planning on the right foot. There are many other freely available resources that can help in your knowledge and trip planning, here are a list of some of my favorites: 

 ARFI- Designed to help private and public avalanche forecasters, guides, and recreationalists. ARFI was developed by the Applied Snow and Avalanche Research Group at the University of Calgary (ASARC). Around 2014, the ownership of ARFI was transferred to Avalanche Canada.

 VizaWeb- The site is awkward and cumbersome to use but provided a great visual of precipitation hotspots. This is I would generally set up the viewer to look at total precipitation accumulation. 

The GFA- The GFA (Graphical Forecast Area) Is produced primarily for pilots by NavCanada.Learning the different symbols and and abbreviations takes some time, but can help with your analysis of visibility/cloud cover, wind and precipitation.

SpotWx- Designed as a spot weather forecasting tool. It offers a variety of weather models and offers data insimilar charts as the meteograms, but without the visual top panel. I usually look at SpotWx to compare models. If there is a lot of model disagreement in the weather forecast I may factor that uncertainty into my trip plan.

Canada RASP- This site was created by a paraglider and provides two visualizations from the HRDPS model. One is a map that primarily shows information about wind at different elevations, and the other is a ‘windgram’ which shows wind and temperature at a single location as a function of altitude over the next one or two days. This windgram also shows atmospheric stability, which can give an indication of enhanced or convective precipitation (especially in the spring!)

Getting the (meteo)Gram!

April 25 is the last day of daily avalanche forecasts in Avalanche Canada’s forecast regions. Danger ratings expire on April 28 and as of April 29, Avalanche Canada’s forecast regions will list Spring Conditions.

Spring is the time of year when conditions can change in the matter of hours. The weather can switch from a wintry storm to intense summer heat quickly, which rapidly affects the snowpack and avalanche conditions.

Although the daily avalanche forecasts for our regions are finished for the season, there are still some great resources to help you plan for a safe day in the backcountry:

Our Spring Guidance can help you plan for the various conditions you may come across this spring. It breaks the spring up into four scenarios, based on the weather, snowpack, potential avalanche activity, and associated terrain and travel advice. This is the go-to for spring travel in avalanche terrain.

The Mountain Information Network hosts observations by fellow recreationists. The blue pins on the avalanche.ca homepage show the shared information. If you do head into the backcountry, please consider submitting your observations to help others. Even just a photograph helps.

Look for nearby Mountain Condition Reports on the homepage too. They show up as blue pins, but with white circles inside them. These reports include high-quality data, submitted by certified professional guides.

Check the Snowpack Summary section for your region of interest on avalanche.ca for a generalized description of the snowpack.

The Dangerator can be a helpful tool to assess for potential avalanche danger if conditions are wintry.

Review the information on the Mountain Weather Forecast page and associated weather products to understand what weather conditions you may experience during your travels. Although the text that summarizes the information may not be available mid-spring into the summer, the graphics can still provide valuable insights. 

Terrain and travel advice will vary for a given day and location, but here are some general tips for safe travel in the spring:

Aim to start your day early and end your day early, particularly during warm, sunny days. Sun-exposed slopes could quickly form wet-related avalanches and cornices could weaken and fail with daytime warming.

If it is stormy, expect storm slab and wind slab avalanche problems at higher elevations. Dial back your terrain choices and give some time for the new snow to bond, particularly if it is sitting on hard, smooth surfaces.

Expect to find very different conditions with elevation and aspect. The snow may be a hard, melting brick below treeline, but a cold snowpack with weak layers may exist in the alpine. Dry snow may persist on shaded slopes while sunny slopes bake in the sun.

Get at it safely, make some memories, and please report your findings to the MIN to help the backcountry community. We’ll see you in November!

Resources for spring in the backcountry

For many mountain sports enthusiasts, spring is their favorite season. The mountains lure us in with a greater potential for good visibility and comfortable temperatures. If you are a skier, mountaineer, or sledder, you know some of the best alpine conditions are found late March into early May. For those into hiking or biking, the valley bottoms will start to melt out providing great low elevation adventures, but spring is not without its challenges.

Loose wet avalanches, like this one in the North Rockies, are common in the spring.

The trick to having a good time in the mountains in spring is understanding the mixed bag of conditions waiting for you. It may be summer at valley bottom and winter on the summit—with a bit of everything in between. This time of year, a good avalanche forecast and knowledge of mountain weather is invaluable in your quest for adventure.

Just like any other day, we start by looking at the avalanche forecast. We want to pay close attention to the elevation and aspect for each problem. Where on our proposed route will we be exposed to each problem? 

Wet loose avalanches are likely to be a problem on east aspects earlier in the day, and become a concern on south and west aspects as the day progresses. At lower elevations, daytime warming and the resulting rise in freezing level may increase the likelihood of this problem.

During periods of rapid warming, large persistent or deep persistent slab avalanches may run all the way to valley bottoms. You may be hiking or biking on dry low elevation trails and unknowingly be exposed to avalanche danger.

Wind or storm slab avalanche problems may still linger in high north facing alpine terrain.

Cornices are largest in the spring and the chances of them falling increases with solar input and above freezing temperatures. These can be a hazard on their own, but they can also trigger large avalanches on the slopes below. Many recreationists have been killed or injured by simply being on a cornice and causing it to fall.

Cornice falls can cause large avalanches on the slopes beneath. This one was in the Northwest region this week.

Convective flurries are common in the spring. These can be problematic for two reasons. They can result in intense localized wind and precipitation, which can create or worsen a wind or storm slab avalanche problem. They can also surprise recreationists with limited visibility in alpine terrain.

There are also other hazards to consider beyond just avalanche problems. The daily rising and falling of freezing levels, commonly referred to as spring diurnal cycle, will usually form a strong surface crust. When this crust is present early in the morning, the likelihood of triggering avalanches is low. However, in steep terrain, this crust could pose a “slide for life hazard”. Self arresting on this firm smooth surface can be challenging.

There are several resources on our website to help in your spring planning beyond the avalanche forecast. The mountain weather forecast is a great starting point for your morning deep dive into expected conditions. Often it will describe unsettled air and the potential for convection, this can be challenging to pick out in local forecast products. Our weather station list can help you find a station near your objective that can help to verify freezing levels and other weather factors. And of course, the Mountain Information Network is full of valuable conditions reports.

Get the forecast, go further, get home at the end of the day. We will see you out there!

Spring Challenges

The coming days are bringing a significant change of weather and a widespread increase in avalanche danger. A combination of existing snowpack instabilities and unseasonably warm weather means the potential for large and dangerous avalanches. 

A large persistent slab avalanche which failed on the early Feb weak layer in the Monashees near Revelstoke last week. These types of avalanches are expected to continue with the upcoming warming and sun. 

Most of western Canada has been entrenched in a pattern of large human-triggered avalanches since the start of March. The culprit of these persistent slab avalanches is a weak layer above a crust that formed in early February. The behaviour of these avalanches is alarming, with many being triggered remotely, releasing in low angle terrain, and starting part way down slopes. These avalanches have persisted almost daily throughout March, despite the layer getting buried deeper and deeper.

Persistent slab avalanche remotely triggered by skiers in lower angle terrain in the Cariboos on March 3 (MIN report from CRAIG HARTMETZ).

Sudden and significant warming is hitting the coast on Thursday and the interior on Friday, with sunny skies and double digit temperatures continuing over the weekend. The impact of this warming is clear—a spike in avalanche danger, with large natural avalanches.

Regions with persistent slab avalanche problems (which includes most of them), can expect very large natural slab avalanches (size 3 to 4!).

Wet loose avalanches will occur on sun-exposed slopes.

Cornices will break, and potentially trigger avalanches on the slopes below.

In addition to natural avalanches, all the above types of avalanches will be very sensitive to human triggering.

Forecasting persistent slab avalanches can be tricky, but under these conditions it is not. The combo of a hyper-sensitive snowpack with intense warming is a recipe for high danger.

Forecast for Whistler village from Environment Climate Change Canada.

Once the warming arrives in your region, we strongly recommend the following precautions:

Choose activities or routes that do not require exposure to avalanche terrain.

Avoid crossing below avalanche paths, including valley bottom trails that pass through runouts.

Remember that many avalanches have been triggered remotely from low angle terrain.

It's a straightforward message – avoid avalanche terrain.

Let's all hope for improved conditions once temperatures return to seasonal norms!

Remotely-triggered avalanche in Kananaskis Country on March 11 (MIN report from MAJOSRNIK).

Warmup Woes

March 3, 2024: Remote triggered from the lookers left, low angle ridge by a group of ski tourers. Cariboo Mountain (MIN user CRAIG HARTMETZ). 

As the Special Public Avalanche Warning (SPAW) ends on March 7 for regions west of the Rockies, it's important to understand that dangerous avalanche conditions are expected to persist in many areas. Buried weak layers within the snowpack remain a significant risk going forward. Apart from in some of our coastal regions (where stormy weather is about to elevate avalanche danger), we are transitioning into a period where it is becoming less likely you’ll trigger an avalanche, but the consequences of an avalanche could still be very high. These persistent weak layers continue to demand respect and it may take weeks or more for these layers to stabilize. Conservative decision-making will remain essential, even with avalanche danger ratings potentially decreasing in some regions.

Remain vigilant and don’t overlook signs of heightened avalanche danger, like fresh avalanches, whumpfs, or shooting cracks. As the weak layer continues to get buried deeper, signs of instability may be less frequent and less obvious. 

Patience will be critical. Don’t be lured into dangerous terrain when there is new snow or sunny weather.

Be diligent about terrain choice. Stick to low-angle terrain without terrain traps, such as cliffs or gullies. 

Minimize overhead exposure. There is lots of recent evidence of remotely triggered avalanches and avalanches that are running far and pulling back into low-angle terrain. 

The following are examples of some of the persistent slab avalanches we have been seeing recently. Avalanches of this nature are expected to persist so continue to check the bulletin daily to see how conditions are evolving and use this to plan your objectives.

March 2, 2024: A large natural avalanche that propagated across the entire feature. Glacier National Park (MIN user CCMSKI)

March 5, 2024: Skier-triggered size 2 avalanche in the Sea to Sky area (MIN user ERIK.EP).

March 4, 2024: Remotely triggered by a ski tourer in the North Coast mountains (MIN user LAMONTAGNE.YANN).

March 4, 2024: Remote triggered large avalanche in the North Purcells (MIN user COLE). 

March 4, 2024: Rider reported no signs of instability in low angle terrain. While stepping out into steeper terrain remote-triggered this avalanche, another size 1 avalanche was sympathetically released just outside the photo. Duffey Lake area (MIN user CHRISRSMITH12). 

March 3, 2024: A wide-propagating avalanche triggered by a snowmobile rider in the South Purcells (MIN user SCOTT.HICKS). 

March 5, 2024: A very large natural avalanche broke ice on the lake below up to 1 km away. Waterton National Park.

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