Let's talk about avalanches, hazards and snowbiking

tribalbc

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So I thought about doing this thread for awhile, even just thought about it the other day and then this tragedy happened. 2 local snowbikers died in an avalanche Monday.


I will start with a bit of my background. I have worked in professional avalanche forecasting and heli ski guiding industry for close to 30yrs. Previous to that I was an extreme skier traveling the world looking for the biggest steepest lines. I grew up in the mountains and have been around snow and avalanches my entire life. I have seen hundreds of avalanches and incidents over the years.
I also grew up dirt biking in the mountains, my other passion. I did plenty of sledding over the years, but used them more often than not to access terrain for skiing rather than just sledding.
Then along came snowbiking. It's the best of both worlds. Skiing and dirt biking in one. Even uses the uphill ski touring skills as your climbing lines are much the same. It is my new favorite pastime and I get out there when ever I have the time from work. Helps that I can literally ride right from my doorstep.
So my plan is to try to pass on some of my knowledge to fellow snowbikers so we can all be safe out there. I will try to transfer the knowledge in a way that is specific to snowbiking and the hazards of the mountains. I know not everyone can be a professional so I will try to not get too technical and provide real world solutions to use.
Feel free to ask questions and I will pick away at different topics over time here. But be aware that when I am working I can be away for weeks at a time, with shoddy internet and not a whole lot of time. So I will keep up with this as I can.
 

tribalbc

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So let's start with the big one, avalanches.
To start I assume everyone reads the public avalanche bulletin? Does it influence your decisions for the day? I hope so because I see way too many people out there doing the exact same thing whether it is low or high hazard, but that is another discussion.
Now you start heading up in the morning and lots of information is being presented to you. Has there been any fresh natural avalanches anywhere. If so are they on a specific aspect or terrain feature? Any natural avalanches is a huge red flag and a sign that it is a day to keep it mellow.
Next, what is the weather doing. Snowing heavily is pretty obvious you have increasing hazard but what about the wind and the sun? Can you see snow moving at ridge top? If so what way is the snow moving and how much. Heavy wind transport is just as dangerous as heavy snow with the addition of adding a reactive windslab at ridge top, or even lower slopes with katabatic winds.
How strong is the sun? The solar effect from the sun not only causes the obvious wet avalanches. It can also take light dry fluffy snow and cause it to become cohesive enough to now form a slab. Now that fluffy snow that would just sluff away has the ability to propagate into a large slab avalanche.
The take from all this is the day starts with a forecast but snow is an ever changing form and you must observe and change your plans accordingly.

More to come.
 

tribalbc

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Okay let's talk about terrain, which is still talking about avalanches.
It is often said there are 3 answers to any guiding problem in the mountains. Terrain, terrain and terrain. You can have a safe day in the mountains whether it is high or low hazard, it's all in terrain choice.
The beauty of snowbikes unlike sleds is you can still have lots of fun in mellow terrain. But we have a weakness as snowbikers in that we love gullies, undulating terrain and we do big sidehills to climb. The gullies and the undulating terrain can be a problem because of terrain traps. It doesn't take a very big avalanche to bury you when the snow has no where to go but filling the big hole your in. People can ride out massive avalanches and end up on top or not very deep if the slope is smooth and has a big long run out into the flats. No where for the snow to pile up it spreads out. But add trees, rocks or dips in the terrain you have a different story.
So how do we deal with this? We start with a morning hazard rating of moderate or lower. Considerable and up you don't want to be around terrain traps. Then when you get to your riding area find a small feature that is really steep and unsupported ( convex more on that later). Look for something around the same elevation and aspect you will be riding. Do a nice big cut/ sidehill across the middle of the feature. Anything happen? No? Starting to feel better. Now do another cut about 2 feet above your last one. Does the piece of snow between the tracks release? Yes? Heads up make some adjustments to plan. No? With a moderate or lower hazard rating, no natural avalanches observed and stable weather then you should be feeling pretty good to rip that risky terrain trap terrain.
Terrain to be continued.
 
Apr 18, 2016
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I am liking this, some of your insight and ways to check are very helpful. I have all the equipment you can buy and have watched a lot of videos like the throttle decisions series. We make a lot of decisions very fast over and over all day and I have often thought about our saw jobs sideways across stuff. I'll be watching this for further info.

I will say something that has kind of concerned me over the years. Last weekend they had it listed as considerable for all aspects at all elevations here in Tahoe. There were zero sightings that I know of and very minimal coverage. I watched all day for signs of considerable threat and played it safe but I am not sure that was actually a fair assessment of the conditions after doing some assesment myself. Do you feel the avalanche watch group might be setting up a bit of a cried wolf scenario when they do this? or maybe where I was at it just never came to fruition but man did it seem to be stable....like super stable.
 

tribalbc

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This is something that as avalanche professionals causes many an argument. I like most believe in telling it like it is, so you have credibility. But there are those especially in the public forecast area that will up the hazard to try to deter people. Ski hills can be the worst for this.
That said considerable can be a tricky area with no signs of activity until you find that sweet spot.
You have to remember it is a hazard rating not a stability rating so size and scale of potential avalanches factors in.
Considerable is the worst place to be with the most uncertainty. At least with high it's pretty obvious what your dealing with.
 

tribalbc

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Ok let's talk about supported vs unsupported terrain.
Unsupported terrain is just like it sounds. The snow has nothing supporting it to the terrain. Convex terrain is a classic, that beautiful roll we want to go over. Because of the convexity the snow wants to literally tear apart from the snow above. The other big one is a slope with a cliff at the bottom. The slope could be as smooth and planar as could be but there is nothing supporting it at the bottom.
Supported terrain is again just like it sounds. Concave terrain is the best example of this. The shape of the concave actually makes the snow stronger. It is held in place by the shape. Even the tinniest bit of a bench feature on a big slope can make all the difference. These lines also make the best climbing lines so reading them will not only make you a safer rider but you will also always have the best climbing line.
 

nregistered

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Last weekend they had it listed as considerable for all aspects at all elevations here in Tahoe. There were zero sightings that I know of and very minimal coverage. I watched all day for signs of considerable threat and played it safe but I am not sure that was actually a fair assessment of the conditions after doing some assesment myself. Do you feel the avalanche watch group might be setting up a bit of a cried wolf scenario when they do this? or maybe where I was at it just never came to fruition but man did it seem to be stable....like super stable.
Or maybe the snowpack was unstable but you didn't dig a formal profile to confirm this? "Considerable" means natural triggers are possible and human triggers are likely. It doesn't mean that because you didn't casually observe avalanches, that "the avalanche watch group was setting up a cried wolf scenario."
 

tribalbc

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Or maybe the snowpack was unstable but you didn't dig a formal profile to confirm this? "Considerable" means natural triggers are possible and human triggers are likely. It doesn't mean that because you didn't casually observe avalanches, that "the avalanche watch group was setting up a cried wolf scenario."

I would never hang my hat on a profile and I think it is a disservice to teach the general public. It is a tool we use but far from definitive as spatial variation is huge. It is a tracking tool rather than a go/ no go tool. I will expand on this later.
Otherwise I agree with what you said as you can see from my post above.
 

nregistered

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You don't have to hang your hat on a profile. That's not what I meant. I meant that rhino only implied casual observations, so maybe he didn't know the details of the snowpack structure. At Moderate and Considerable, it helps to know the snowpack, because otherwise you might not get much feedback.

In rhino's case, he's saying he didn't get any feedback, and is therefore questioning the danger rating. No feedback does not equal no danger, especially at Moderate and Considerable.
 
Feb 4, 2011
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This is awesome @tribalbc and good for you for taking the time here to talk avalanches. I'm a public avalanche forecaster in Utah. I'd like to contribute to the conversation here but I don't want to step on your toes. Perhaps you are going to talk about the importance of what type of "Avalanche Problem" presents itself from day to day? Are avalanches likely because of new snow? Or perhaps windy conditions? Or perhaps, the most deadly, a layer of sugary faceted snow buried within the snowpack? Riders need to behave differently with the different types of avalanche problems.

In many areas of the west this season, we're dealing with a "Persistent Weak Layer" of faceted (sugary) snow near the ground. It's called a "Persistent Weak Layer" because it can persist for weeks or months causing avalanches with (and after) each storm. This is a bad set up and it's the type of situation where higher danger ratings might be present in forecasts for long periods of time. That's where we are here in Utah right now. Bottom line, you can't mess around with a known buried "Persistent Weak Layer". It'll bite you long after you might think things are safe.
 

tribalbc

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This is awesome @tribalbc and good for you for taking the time here to talk avalanches. I'm a public avalanche forecaster in Utah. I'd like to contribute to the conversation here but I don't want to step on your toes. Perhaps you are going to talk about the importance of what type of "Avalanche Problem" presents itself from day to day? Are avalanches likely because of new snow? Or perhaps windy conditions? Or perhaps, the most deadly, a layer of sugary faceted snow buried within the snowpack? Riders need to behave differently with the different types of avalanche problems.

In many areas of the west this season, we're dealing with a "Persistent Weak Layer" of faceted (sugary) snow near the ground. It's called a "Persistent Weak Layer" because it can persist for weeks or months causing avalanches with (and after) each storm. This is a bad set up and it's the type of situation where higher danger ratings might be present in forecasts for long periods of time. That's where we are here in Utah right now. Bottom line, you can't mess around with a known buried "Persistent Weak Layer". It'll bite you long after you might think things are safe.

No problem with stepping on any toes here Brett. Egos don't work well in our industry. All welcome to contribute. Just want to stick to good science though and keep the internet "experts" at bay.
My intention is to try to stay away from getting too technical and keeping things to some simple techniques and observations that anyone can do and make their day safer.
I say for the general population don't get wrapped up in weak layers, profiles, etc. The technical jargon just clouds the waters.
Work with simple solutions everyone can employ. A hazard rating, observations of changing conditions, and good terrain choices. If you can get enough people just making these simple changes it can save a lot of lives.
 
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This thread has the potential to be one of the best threads I have read on here in quite some time. I consider myself fairly conservative when it comes to route selection but still occasionally find myself in the "What the hell were you thinking on that line choice situation?" The more knowledge and tools you can ad to my toolbox the better so thanks for doing this.


M5
 
Feb 4, 2011
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No problem with stepping on any toes here Brett. Egos don't work well in our industry. All welcome to contribute. Just want to stick to good science though and keep the internet "experts" at bay.
My intention is to try to stay away from getting too technical and keeping things to some simple techniques and observations that anyone can do and make their day safer.
I say for the general population don't get wrapped up in weak layers, profiles, etc. The technical jargon just clouds the waters.
Work with simple solutions everyone can employ. A hazard rating, observations of changing conditions, and good terrain choices. If you can get enough people just making these simple changes it can save a lot of lives.
Simplicity is key. Big fan. I do think it's worth talking about the various avalanche problems at some point. The important thing for folks to understand is that you'll want to behave differently during, for example, a MODERATE avalanche danger with a "New Snow" avalanche problem versus a MODERATE avalanche danger and a "Persistent Weak Layer" avalanche problem. We'll work this in at some point. Carry on!!
 

tribalbc

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Simplicity is key. Big fan. I do think it's worth talking about the various avalanche problems at some point. The important thing for folks to understand is that you'll want to behave differently during, for example, a MODERATE avalanche danger with a "New Snow" avalanche problem versus a MODERATE avalanche danger and a "Persistent Weak Layer" avalanche problem. We'll work this in at some point. Carry on!!

Agreed. Good points.
Well I am going riding today so to be continued later.
 

portgrinder

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Our group is always talking about smaller slides in the trees. I think that’s where a person is going to get caught.

After a while, most snowbikers quit thinking like sledders and start getting real creative in the trees. Even a small slide can cause big trouble if is pushes you into a terrain trap, creek, trees, over a cliff.

I’m always looking for ‘ok if this let’s go, what am I going to be pushed into’. Also a big reason to use the buddy system. How many times are you playing in a group where you have no real idea where all your folks are. A person could be in trouble for a long time before anyone realizes. Not like a big open slide where everyone knows it happened.
 

needpowder

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Tribal, thanks. Awesome thread. This topic can never be discussed enough. I am fortunate enough to live in Utah with a team of avalanche forecasters and ski resort professionals who are amazing. I read the forecast every day whether I am heading to the mountains or heading to work. Unfortunately, we are dealing with a persistent weak layer here (like many places right now). Although it seems to be healing a little bit, like Brett said, a moderate danger in these conditions is extremely scary still. We are riding the terrain accordingly. Cannot wait for a moderate danger for fresh snow avalanches only—what my riding group affectionately refers to as “surface peels”. Keep up the good work!
 

tribalbc

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Our group is always talking about smaller slides in the trees. I think that’s where a person is going to get caught.

After a while, most snowbikers quit thinking like sledders and start getting real creative in the trees. Even a small slide can cause big trouble if is pushes you into a terrain trap, creek, trees, over a cliff.

I’m always looking for ‘ok if this let’s go, what am I going to be pushed into’. Also a big reason to use the buddy system. How many times are you playing in a group where you have no real idea where all your folks are. A person could be in trouble for a long time before anyone realizes. Not like a big open slide where everyone knows it happened.

Awesome, you guys are on the right track.
It's all about situational awareness. What could happen here? What are the hazards? Where's my out?
As you say it doesn't take a very big slide or feature to be a killer if there are terrain traps, obstacles. A big obstacle to be discussed later is tree wells.
The accident that happened in Pemberton was a classic example of that. Not a very big feature, 35 degrees tree glade with only a moderate hazard called. But that day 4 different large human triggered avalanches happened. Another sled skier was pulled out blue but recovered, another sledder was buried and injured and another skier was badly injured. All from a surface hoar layer down 60 - 100cm down that was showing in the moderate to hard range results in pits and no natural activity.
If you go to https://avalanche.ca/
Just north of Pemberton on the map is a red pin. Click on it and it will give you details and pictures of the accident.
 

tribalbc

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Tribal, thanks. Awesome thread. This topic can never be discussed enough. I am fortunate enough to live in Utah with a team of avalanche forecasters and ski resort professionals who are amazing. I read the forecast every day whether I am heading to the mountains or heading to work. Unfortunately, we are dealing with a persistent weak layer here (like many places right now). Although it seems to be healing a little bit, like Brett said, a moderate danger in these conditions is extremely scary still. We are riding the terrain accordingly. Cannot wait for a moderate danger for fresh snow avalanches only—what my riding group affectionately refers to as “surface peels”. Keep up the good work!

Yeah you guys deal with a completely different animal than I do in my work on the coast. I grew up in the Rocky mountains of Canada so I am very familiar with a continental snowpack but I can tell you I don't miss it.
Here we have that surface hoar issue but over the next 3 days we are receiving 2 meters of wet coastal snow with high winds so the whole world is going to fall down and then more than likely the issue will be over.
At my work further north our range goes from a full coastal pack to continental over the course of about 100kms. We tend to ski in the coastal and transition zone but do spend some time on the dry side.
 
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