How to Make Sense of the Avalanche Forecast
Hey, guys. It’s Sarah from Miss Adventure Pants. I’m here today to show you how to read the avalanche forecast.
When I first moved to Colorado, and I wanted to go snowshoeing, people would always say, “Well, have you read the avy forecast?” And I would go and look at it, and my head would explode.
It’s just not as straightforward as I’m sure we all wish it was. But I’m going to walk you through the basics today.
One thing I really want to emphasize to you — if you get nothing else out of this video — is that it’s so important to have avalanche education if you’re going to be in the winter backcountry.
Take your AIARE course. Don’t rely on videos on YouTube to keep you safe.
There’s nothing like being out there with an expert who can point things out to you and show you things in the field. That’s what’s going to really increase your judgment about these things.
But I will show you the basics, so come along with me.
How to Find Your Avalanche Forecast
First, let’s talk about where you can find the forecast for your area. There are different avalanche forecasting centers all over the country.
If you’re in the United States, this website, Avalanche.org, has a handy map.
Say I want to know what’s going on in this part of Washington State. I just click on the map, and it can send me straight to the forecasting center for that area.
- There’s also a website called Avalanche Canada that uses the same rating systems as the U.S.
- Europe and New Zealand also have very useful avalanche forecast websites. (Though their rating systems may be different.)
I’m in Colorado, so I’ll use our forecasting center for this demo. The forecast format for your area may look slightly different, but you should be able to get pretty much the same info.
Here’s the Colorado Avalanche Information Center site. As you can see, it’s been snowing like crazy in Colorado, so this is the perfect day to do this. We even have one region down here [South San Juans] that is super high avalanche danger, so we’ll definitely take a look at that.
But first, let me show you two more things.
First Is the North American Public Avalanche Danger Scale
The top two ratings, we actually don’t see those super often. I think I’ve only seen “extreme danger” maybe two or three times in many years of living in Colorado.
Whenever we have these conditions, the decision-making is easy. We just don’t go out. Or if we do, we stay far away from avalanche terrain, which basically is any slope over 30 degrees.
Where it gets a little trickier is down here in the considerable-to-moderate range.
This is where decision-making and judgment come into play. You need to be able to assess the danger and plan the safest route of travel and understand the risks that are out there.
It’s interesting. A fair number of people who die in avalanches die when the danger level is moderate.
Part of that is that more people are out, because it’s usually not in the middle of a snowstorm.
But people also get complacent. They see “moderate” danger and think, “Well, that’s not too bad. I can go wherever I want.”
Don’t do that. Because I love you, and I don’t want you to die in an avalanche.
Low danger: these are generally safe avalanche conditions. You can definitely still have isolated areas that are dangerous, so it’s still good to know what to look for. But generally you’re pretty safe.
There Are Also Different Kinds Of Avalanche Problems.
Avalanches have different causes, different behavior. So it’s good to know what kind of problems you’re likely to see.
You tend to find different problems in different parts of the country. I’ll show you a couple that we deal with a lot in Colorado.
Storm slab and the wind slab
These usually occur in new snow that hasn’t had time to consolidate and stick to the layer below after a storm. Usually, a storm slab avalanche will release right underneath your feet. These don’t tend to be giant avalanches, but they can certainly be big enough to bury you. Which is big enough, from your point of view.
Persistent slab and deep persistent slab
These actually form over weeks or months. They happen whenever snow consolidates over a weak layer. If there’s stress, the upper layers can slide down the weak one like a sled.
These tend to be very big, destructive avalanches. Deep persistent slab in particular can be huge.
They can also be triggered from a distance. So even if you’re walking at the bottom of the slope, you can trigger an avalanche up on top that can slide down and get you.
If you look on YouTube, there are some crazy videos of people walking on a ridge and triggering one of these, and the whole side of the mountain falls off. It’s insane. These are the big, bad ones you don’t want to see in your forecast.
These happen more in the springtime when the snow’s heating up, and it turns into a big slush pile that slides down and hits you. Not much fun.
But I’ll let you read more about these on your own. Get to know some of the common avalanche problems in your area.
Now Let’s look at some forecasts.
I’m in Denver, and I go snowshoeing a lot in the Front Range. Let’s take a look.
Okay. As you can see, moderate danger today and moderate danger tomorrow. And it’s above treeline, near treeline, and below treeline, in both cases.
Below that, we have a very nice summary. I love that the very first sentence is, “You can trigger unsurviveable, deep persistent slab avalanches that break into weak layers near the ground today.” Awesome.
But it does give you some tips to help reduce your risk. Like today, avoid slope angles over 35 degrees and all northerly and easterly facing terrain. So that’s good to know.
And if you scroll down, It shows you different problems that you might find. So deep persistent slab on north and east-facing slopes is a problem right now. It’s not super likely to be happen, but if it does, it could be very large.
One awesome thing about this site is you can look at pictures. These actually aren’t super huge for deep persistent slab avalanches, but you can kind of get an idea.
See how even from a distance, this avalanche crown looks like it could be 6 to 10 feet tall? That’s pretty dangerous if you’re a skier coming down.
And it looks like there was a skier. But he came down before the slide, because you can follow his tracks off the screen. Lucky skier.
It also looks like we have a wind slab problem below, near, and above treeline right now, and the forecast shows you which aspects those are on.
Avalanche forecasting sites also have a lot of really great information about weather as it relates to avalanches. If you click this tab [forecast discussion], you can read an in-depth analysis.
Some of it might feel a little bit over your head, but it’s good stuff to read. Just start trying to put it together, especially as you’re learning about avalanches and the science of how they work.
Let’s go back, just for fun, and look at this high-danger forecast.
This is for a mountain range in southern Colorado [the south San Juans] that just got hammered with snow yesterday.
Here you can see the avalanche danger is actually high above and near treeline.
And if we come down to the summary, it tells us: “Natural and human-triggered avalanches, large enough to bury or kill a person are likely today.”
So, yeah. I don’t know about you, but I will be staying below treeline!
If you look at problems, they have persistent slab, just like the Front Range. But it’s more likely to slide, now that the snow pack’s under more weight from this big dump of snow they got.
And here’s storm slab. Like I mentioned above, these avalanches are likely to occur in new snow. According to this, they’re pretty much everywhere in the South San Juans right now. So you’re not really safe unless you’re completely off of avalanche terrain and away from any steep slopes.
So Yeah. Avalanche forecasts are fun things.
I hope you had fun looking at that with me.
And again, I really hope that you pursue your avalanche education if you’re going to be in the backcountry recreating. Because then you can have fun, you can do more things, and you can go with confidence.
Really, the winter is one of the best times to be in the mountains. It’s just incredibly beautiful and quiet, and I hope that you’ll go and get the skills, so you can go out and enjoy that.
Okay, thank you so much for hanging out with me. I’ll see you here again soon and have a good day. Take care.