In this episode of Ask The Experts, find out what you need to do if you're ever caught in an avalanche.
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00:00Welcome to AccuWeather's Ask the Experts, I'm Jeff Cornish.
00:15We go beyond the forecast to give you the how and why on all the cool and interesting
00:19things you've wondered about and wanted to ask in weather, space and science.
00:23Today we're talking about avalanches, the natural disaster centered on winter and early
00:29spring a lot of the time in areas that get extreme snowfall.
00:32They can be deadly and depending on their severity they can literally change landscapes.
00:37So our expert leads a team that specializes in avalanche safety in the Colorado mountains
00:42and the Rockies and joining us right now is Ethan Green, he is the director of the Colorado
00:47Avalanche Information Center or CAIC and Ethan thanks so much for making time for us here
00:52on your busy day.
00:55No problem, thanks for having me.
00:56Absolutely, I think this is a fascinating topic and obviously it inspired the name of
01:01the major NHL team there in the Centennial State.
01:04So while avalanches are certainly not something the average person may come in contact with,
01:09they are certainly a big news item and we see and hear a lot about them when they do
01:13occur.
01:14So you've been working on avalanches for over 30 years and have been director of the CAIC
01:19since 2005.
01:20So tell us about your career and give us some insight into the work of this important organization.
01:26Well, like you said, I've been doing this type of work a long time in sort of different
01:32ways but almost 20 years at the CAIC and so we're a statewide group focused on trying
01:38to help folks with avalanches.
01:41That could be transportation along the highway corridors, municipalities, occupied structures,
01:48but a lot of what we do and sort of the most people that we interact with is putting out
01:53daily forecasts of the avalanche hazard for backcountry recreation.
01:57So people that are heading into the Colorado Mountains to ski, snowmobile, climb, snowshoe,
02:02whatever their activity of the day is, we're providing information for them so they can
02:07make good decisions and hopefully have a good time in the backcountry and come home safe.
02:11And this could absolutely be life-saving information and we want to talk about the science of avalanches.
02:18And I'm a little bit of an outsider when it comes to avalanche mechanics, but we understand
02:21there might be two kinds of avalanches in general.
02:25What do we know about their causes?
02:27Well, depending on how you look at it, there's a few different types of avalanches.
02:32A really common way for us to look at it is in terms of whether the snow has liquid water
02:37content or not, so wet or dry avalanches.
02:41And then the most dangerous avalanches are what we call a slab avalanche.
02:45So not just the particles of snow or ice kind of rolling down the hill like a snowball,
02:51but a cohesive layer of snow that breaks off the hillside and runs down into the valley.
02:56And we get those when we have a weakness in the snowpack, so lower down below the snow
03:01surface that is conducive for a crack to propagate, and those can go very long distances.
03:07One of the really amazing things about avalanches is that a very small input, like just a skier
03:13on a slope, can release thousands of tons of debris under the right circumstances.
03:21And what are some of the warning signs of unstable snow and ice?
03:25Well, the biggest warning sign is other avalanche activity.
03:30This avalanches tend to release in patterns because they're produced by weather patterns
03:34moving through the mountains, so we tend to see patterns in terms of location, the direction
03:39of the slope faces, and the elevation of that slope.
03:43And so if you see an avalanche, a recent avalanche on a slope that is similar to the one that
03:48you're crossing, it's a good time to go someplace else.
03:51The other signs of instability that we often talk about are cracking or collapsing in the
03:58snowpack.
03:59So you're moving out onto maybe a mellow slope, something that's fairly low angle, and you
04:04hear this big whoomph and see cracks shooting across.
04:07That's a really good sign that if you moved onto a steeper slope, you would be triggering
04:12an avalanche.
04:14And how is the avalanche forecast put together?
04:17Is this something that changes day-to-day, or is it slightly broader in scale in terms
04:21of time?
04:23It does change from day-to-day.
04:25The conditions for any particular day are really a combination of the weather that we've
04:30had all winter long and then the weather we're having that day, and that's because each weather
04:36event that we have during the winter, a snowstorm, a windstorm, a sunny period, produces a layer
04:41in the snowpack.
04:42And if you go up into the mountains and dig down in the snow, you'll see all these different
04:46layers that form, sort of like the rings on a tree, and avalanches tend to break at
04:52the interfaces of those layers.
04:53And so how those layers form is our past weather, and then the weather we're having today is
04:59going to potentially overload those layers and cause avalanches to release.
05:04And besides checking the avalanche forecast before heading out, what are some basic avalanche
05:08safety tips that you can share?
05:11Well checking that avalanche forecast is the most important thing.
05:14Get current information so you know what sort of hazards are out there on that particular
05:19day.
05:20A little bit of education is going to help you apply that information much better.
05:24So whether that's going online, listening to a podcast, or taking a class that's in
05:30the field, a little bit of information could save your life.
05:34And then if you are going into avalanche terrain, having proper equipment.
05:38There's a lot that you need to be going into the mountains in general, but for avalanches,
05:43it's really an avalanche rescue transceiver, a probe pole, and a shovel.
05:47Every person in your group needs to have those three pieces of equipment and know how to
05:51use them.
05:52Okay.
05:53Any other safety equipment beyond those three items that are additional helps when people
05:58are out skiing, hiking, or doing other winter activities?
06:02There certainly are other types of rescue equipment.
06:05There's avalanche airbags or balloon packs.
06:08These are packs that if you do get caught in an avalanche, you can trigger a balloon
06:12that helps you stay on top of the flow.
06:15But really the most important piece of equipment is the one that we're all carrying between
06:20our ears.
06:22If you use that to stay out of avalanches, you're going to have a much better chance
06:27of enjoying the backcountry and coming home safe.
06:30And are there any long-term trends in maybe recent years or decades or centuries even
06:35when it comes to avalanches in the United States, especially over the last several seasons?
06:40Well, there are some pretty long-term trends.
06:43When we start to look at the recent history, it fluctuates pretty dramatically based on
06:48both the amount of winter precipitation we're getting and the order that those storms come
06:54in.
06:55So that's why checking the forecast wherever you are each day before you're going out is
07:00so important.
07:01It's because we really see things fluctuate a fair amount.
07:05You'll see some trends over kind of days and weeks, but getting that current information
07:10is the most important thing that you can do.
07:12And do you know if avalanches are occurring more frequently now in general than 30 years
07:17ago or are we just kind of sensing them more so it's documented better?
07:22Any obvious trends there?
07:25We actually really don't know because the number of avalanches that we document is a
07:28fairly small fraction of the total number.
07:31We do have some indications that historically, not so much 30 years ago, but maybe 100, 150
07:39years ago that we were seeing more and larger avalanches.
07:43But the information that we have right now, it's really hard to tell how much things are
07:47changing over kind of a 10 or 20 year period because the amount of data that we have is
07:53really just a small portion of the total amount that's out there.
07:57That makes sense.
07:58There are a lot of weather variables that we're sampling way better now than ever before.
08:01The biggest rate of change for certain things might be the way that we observe them and
08:04document them, but then there are other things that we have a good baseline for a long period
08:08of time.
08:09Well, let's get to our first viewer question now.
08:11This comes from Courtney in Colorado.
08:12Courtney writes, what is some advice you can share if someone finds themselves facing an
08:16avalanche?
08:17Well, of course, the most important thing is to not get caught in an avalanche.
08:22But if you do get caught, we know that the things that kill you are some traumatic injury
08:28while the avalanche is running and then getting buried in the avalanche and not being able
08:33to breathe in the debris.
08:35So the most important thing, again, don't get caught.
08:38If you do get caught, try to get out as soon as possible.
08:41If you can't get out, try to stay on top.
08:44Very good.
08:45Simple advice there.
08:46Ethan, a quick question.
08:47Is there a very different type of avalanche that might occur in Colorado as opposed to
08:51in, say, the Washington Cascades where there's a different type of moisture there?
08:57The avalanches are really the same, but what triggers them can be different.
09:01In Colorado, we tend to get structural weaknesses that form throughout the snowpack.
09:07They get buried in the snow, and they produce avalanche cycles for days, weeks, and months.
09:12When you move to the coastal ranges of the United States, most of the avalanche cycles
09:16are triggered by really big precipitation events.
09:19So big storms that come in, snows a lot, a lot of wind gets moved around, and that's
09:24what triggers your big avalanche cycle.
09:27The avalanche danger ramps up very quickly and then drops very quickly, whereas in Colorado,
09:32it kind of ramps up and then it drops very, very slowly.
09:36Are there any surprising misunderstandings that people have or things that maybe people
09:40assume wrongly about avalanche danger when it comes to the Colorado risk?
09:46One of the common misconceptions is that really loud noises will trigger avalanches.
09:53In old Hollywood movies and some cartoons, you'll see that represented, and that's really
09:58not the case.
10:00We do trigger avalanches with explosives, but it's the concussion wave, a much more
10:04energetic wave than the sound wave that's producing that.
10:08Most of the avalanches that people get in trouble with, they're triggering themselves.
10:13Either somebody in the group or the person that gets caught triggers the avalanche.
10:18It's really about us being in the wrong place at the wrong time and not just a loud bang
10:23or somebody yelling or a marching band going through the mountains with drums and cymbals.
10:29Great information so far, Ethan, and we have a lot more to talk about with you coming right
10:33up after this upcoming break.
10:34Coming up later in the show in WeatherWise, we're going to have some surprising numbers,
10:39we love weather stats, about avalanches, including just how fast they can move in our Weather
10:45by the Numbers segment.
10:47But up next, we're going to go over some of the places that are the most dangerous
10:50when it comes to avalanches, plus we will have more of your viewer questions coming
10:55up when Ask the Experts continues, so stay with us.
11:05Welcome back to AccuWeather's Ask the Experts, I'm Jeff Cornish, and today we are talking
11:09with Ethan Green.
11:10Ethan is the director of the Colorado Avalanche Information Center, or CAIC.
11:15We're talking about avalanches, avalanche safety, and all the interesting facts you
11:19need to know about them.
11:20Some of this information can keep you safer when you're out and about in the Rockies.
11:25So Ethan, are you able to tell us what it feels like to be caught in an avalanche?
11:30Well, it really depends on the size of the avalanche, but a big avalanche is a really
11:37traumatic event because you have thousands of tons of snow rolling down the hill.
11:44It's very turbulent, so super disorienting.
11:48Some people really get injured very badly or even fatally just in the ride itself.
11:56It seems pretty terrifying for anybody caught in that kind of an environment.
11:59So we're going to talk about the danger scale for avalanches, and we have a 1 to 5 scale,
12:04we understand.
12:05So could you elaborate a little bit on that?
12:07Yeah, it's a really coarse way for us to communicate what the danger is for anybody going out into
12:15the backcountry.
12:16It has to do with how easy it is to trigger an avalanche, how many places you could trigger
12:21that avalanche, and whether those avalanches are likely to release on their own spontaneously
12:28or need a human trigger, somebody to actually cross the slope.
12:33When the danger is low, it means that there's still a chance that you could encounter an
12:39avalanche, but that chance is really low.
12:41They're not very easy to trigger.
12:43They're not very common.
12:44When you start to get up into high and extreme, that means that really probably you want to
12:49avoid traveling in the mountains as much as possible.
12:53Most of the fatal accidents happen in that middle range, that moderate considerable levels
12:59two and three, and that's where the dangers are not quite so obvious, but there's still
13:04some specific places where you could get into trouble, and those are highlighted in the
13:10avalanche forecast.
13:11That's why it's so important for people to read that forecast each day.
13:15And where do people get in the most trouble when it comes to avalanches?
13:19Are they often more remote places, or sometimes are they in the middle of a commercially run
13:24ski slope?
13:25Well, it's pretty unlikely for them to happen in the middle of a commercially run ski slope,
13:30and that's because those businesses, the ski areas, have a sophisticated team of folks
13:37that are going out there and forecasting the avalanche danger within the ski area boundary
13:43and reducing the avalanche danger before people go out.
13:46Just like they're grooming the slopes, they're doing a whole lot of work before people go
13:51out onto the hillside to groom the slopes or remove rocks, whatever they're doing, they're
14:00also doing that work for avalanches.
14:02So most of the avalanche accidents happen in the backcountry.
14:07That can still be very close to a highway, adjacent to a ski area, it doesn't have to
14:12be deep in the wilderness, it just has to be in a natural snow environment.
14:16And I'm sure there's some coordination and collaboration between your agency and those
14:21who are involved in the rescue operations.
14:24So can you talk about a particular rescue mission that you're aware of, what may have
14:28been the cause, and what made certain rescues so memorable?
14:31Is there one in your mind that jumps out?
14:34Well, unfortunately, we support search and rescue on numerous rescues each year, so there's
14:41quite a lot of them.
14:42I think the ones that kind of stand out are often where people are not wearing an avalanche
14:48rescue transceiver or some sort of location device, because that means that you're going
14:54to have a much more difficult and prolonged rescue.
14:58So whenever you're going out into the backcountry and going into avalanche terrain, making sure
15:04that you're searchable in some ways is super important.
15:07And the easiest way to do that is to have that avalanche rescue transceiver.
15:11It's a small radio device, you turn it on in the morning, it sends out a signal, and
15:16then if you do get into trouble, that signal is still getting sent out and other people
15:22can turn theirs to receive, pick up your signal, and pinpoint your location.
15:26Ethan, we have time for our next viewer question.
15:30This one comes to LeVar in California.
15:33What would you like to ask the experts?
15:36I have a question.
15:39Can a single person trigger an avalanche?
15:43Yeah, it's a really good question, and the answer is yes.
15:48It's one of the really interesting things about avalanches as a natural hazard.
15:52If you think about hurricanes, tornadoes, floods, those are not things that people cause.
16:01It's not something that we cause on a particular day.
16:04Whereas with avalanches, under the right circumstances, we can have a bluebird day in Colorado, beautiful
16:10snow on the mountainside, and if you cross the wrong slope at the wrong time, you could
16:15trigger a very large avalanche just from your presence on that slope.
16:20All right, good stuff, and I think this will be our final question coming up here.
16:24Our next question comes from Bradley in California, and Bradley writes, what impact might climate
16:29change have on avalanches?
16:32Well, climate change is definitely affecting avalanches, but exactly how is a little complicated,
16:38and of course it changes from place to place.
16:41But as the global temperatures warm, we may be seeing more wet avalanches and more wet
16:47avalanches in places and times that we typically didn't see them.
16:51Certainly here in Colorado, having a rain event high in the mountains in January was
16:56really unheard of 30, 40 years ago, but we do see those events now in Colorado.
17:03We also start to get more moisture-laden and intense precip events, so whether it's atmospheric
17:12rivers that are affecting the coastal ranges or penetrating deep into the continent and
17:18producing avalanche cycles in Colorado, we're starting to see more intense events like that.
17:23They may not be super common, but when they happen, they're devastating.
17:29We really appreciate all of your insight.
17:30Ethan Green, Director of the Colorado Avalanche Information Center.
17:34Ethan, thanks so much for your time here today.
17:37Don't forget, when you have a question about weather, space, or science, you can write us
17:40or send us a video question at asktheexperts at accuweather.com.
17:44You can also call us at 888-566-6606.
17:49Coming up next, we're going to test your avalanche knowledge in our weather by the
17:52numbers segment.
17:53Do you know the top speed of an avalanche?
17:55We've got the answer after the break.
18:04It is now time for weather wise.
18:06In a segment we call weather by the numbers, today we look at avalanches and some surprising
18:11statistics about them.
18:13So there it is.
18:13Our first number is 80.
18:1580 is the speed in miles per hour that an avalanche can travel.
18:20So here we're talking mainly about dry slab avalanches.
18:23These are the faster ones.
18:25They can happen so fast that a dry slab avalanche can reach up to 80 miles per hour within just
18:30five seconds of the beginning.
18:33Wet avalanches do tend to be slower, so these wet avalanches usually travel around 20 miles
18:38per hour.
18:39Still pretty tenacious if you're out there on the slopes.
18:42Our next number is 18.
18:44That's 18 minutes.
18:46If rescuers can get to an avalanche victim within the first 18 minutes, the survival
18:51rate is 91 percent.
18:53Now if you're still trapped after the first 18 minutes until about 36 minutes after the
18:57avalanche, the survival rate falls to just 34 percent.
19:01After an hour, only one in three victims buried in an avalanche are found alive.
19:07Finally, our last number is 90.
19:09That's 90 percent.
19:10So here we're talking about in nearly every avalanche involving people, either the victim
19:16or someone in the victim's group is usually the cause for the avalanche.
19:21Often the snow slide is triggered by a person's body weight providing enough extra stress
19:25on the snow to collapse a weaker layer of snow beneath.
19:29So in 90 percent of cases involving a human victim, a person is the cause for the avalanche.
19:34Thanks so much for being with us here on AccuWeather's Ask the Experts.
19:37I'm Jeff Cornish.
19:38Remember, when you have a question about weather, space, or science, you can email us at
19:42AsktheExperts at AccuWeather.com or you can call us at 888-566-6606.
19:49Have a great one.