2012 Season Summary

By Doug Chabot

12 April 2012

Greetings!

We just wrapped up our 22nd season of avalanche forecasting with 138 advisories.  It was a busy, challenging winter and Mark Staples, Eric Knoff and I want to thank everyone for their support.

The winter started out with La Nina’s flirtatious promises.  We truly believed we were going steady, reaping her gifts of deep and plentiful snow, but in the end she wouldn’t return our calls.  We were jilted for Alaska and lived with below average snowfall for most of the season which allowed weak, faceted snow to form at the ground.  This poor snow structure led to many avalanches and prolonged periods of dangerous conditions.  The first measurable snowfall occurred on November 6th with the season’s first avalanches reported the next day.  We issued intermittent avalanche bulletins until beginning daily advisories on December 7th.  By the time the first large snowstorm arrived on December 29th, the snowpack’s foundation had changed to rotten, airy depth hoar.  We issued our first Avalanche Warning on the 30th.  Before sunset on the 31st there were two separate avalanche fatalities outside Cooke City involving a skier and snowmobiler.  Seven weeks later a huge snowstorm on top of an unstable snowpack led to a third fatality outside Cooke City, also involving a snowmobiler.  Over the course of the winter we issued five separate Avalanche Warnings, a new record.  The persistent weak layer at the ground caused some slopes to avalanche two or three times.  There were many close calls in the backcountry.  At season’s end, besides the three fatalities, 51 avalanche incidents were reported.

THE GNFAC INDEX
• Total number of people getting our advisory every day: 4,365
• Percentage increase over last year: 15
• Number of “Likes” on Facebook and “Followers” on Twitter: 1,953 and 836
• Total number of avalanche classes taught and individual attendees: 80 and 4,411
• The number of Level 2 avalanche certification classes offered for snowmobilers by the GNFAC: 1
• Total number offered in the entire US, ever: 1
• The number of YouTube videos made this season about the snowpack: 55
• Number of views: 117,039
• Number of miles logged on each of the two Yamaha Nytro snowmobiles that were donated by Cooke City Motorsports: 1,350
• Estimated  highway miles we drove to access the field: 14,000
• Number of field days: 110
• Days that volunteers accompanied us into the field: 84
• Gallons of coffee downed by Doug this season (estimate): 30
• Amount the Friends of the Avalanche Center spent this season on education, weather stations, administrative support and snowmobiles, respectively: $29,681; $6,200; $4,296; 2,500
• Total amount the Friends have spent in support of the GNFAC since 1992: $258,000
• The number of incidents and fatalities in the Gallatin National Forest since our inception 22 years ago: 715 and 38

Running the Gallatin National Forest Avalanche Center is a community wide effort.  We rely on volunteers and broad financial support for our daily operation.  Contributions from the Friends of the Avalanche Center and a Recreation Trails Grant from Montana Fish, Wildlife and Parks total 45% of our yearly budget.  We are indebted to the recreation community and local businesses for supporting the Friends every year.  The success of the GNFAC is a direct reflection of these strong local ties.  Thank you for another great season.

What is “MODERATE”: Understanding the Avalanche Advisory

By Scott Savage, Friends of the Avalanche Center

Published in the Big Sky Weekly, February 2012

“For today, it’s still possible to trigger an avalanche and the danger is rated MODERATE.”     Gallatin National Forest Avalanche Center (GNFAC) advisory, Valentine’s Day 2012

When you’re peering over the tips of your skis getting ready to drop into your favorite powder shot or idling your sled in the flats looking up at the pristine bowl you’re about to highmark, you’ve already made your avalanche hazard evaluation.  You probably started by checking out the GNFAC website (www.mtavalanche.com) at home and read that the avalanche danger was rated MODERATE for the day.  But what does that mean?  And how do they come up with those danger ratings?  Is the danger rating all you need to know or just a piece of the avalanche puzzle?

The avalanche danger rating (sidebar graphic) is a snapshot of the avalanche hazard for a given area, usually a mountain range or specific portion of a range.  Unfortunately, snow stability tends to vary considerably from slope to slope; while the danger for a mountain range may be MODERATE, some individual slopes will be very stable and a few slopes may be highly unstable.  Simply checking the danger rating before you head out to play and assuming that all slopes will behave similarly is a common mistake that recreationists make.  The avalanche danger rating is a great starting point, but you must determine the hazard on the specific slope you choose to ride!

Avalanche centers and forecasters act as information clearinghouses, collecting weather, snowpack, and avalanche data to produce a danger rating each day.  The one-word description of the avalanche hazard (LOW, MODERATE, HIGH…) gets you thinking about the expected avalanche conditions, but it’s just scratching the surface as far as the information that the advisory provides.  What else is in there?

·       A great local mountain weather forecast.  These guys usually blow away the TV weathermen and the National Weather Service forecasters because avalanche forecasters are focused on predicting the weather in the mountains where “the goods are” instead of in town.  

·       Bullseye data.  Recent avalanche activity, collapsing and cracking in the snowpack, and whoomphing noises are red flags in the avalanche world and make stability evaluation simple – this is bullseye data.  Look at the pictures and videos of recent avalanche activity.  A picture of an avalanche can be worth more than 1000 words, especially if it’s next to a slope you planned on riding.  Read the narratives and stories in the advisory that detail firsthand accounts from recent visits to specific areas – more great info that you don’t need an Avalanche PhD to interpret!

·        Pearls of wisdom.  The narrative style of GNFAC advisories allows the forecasters to introduce snow science and stability evaluation concepts.  Take advantage of these free mini-avalanche classes.  While it’s not the same as experiencing things in the field, taking 10 minutes to read and thoroughly understand the advisory every day is a great introduction to avalanche education.

Winters like this one – calling it winter seems like a stretch – challenge sledders, boarders, skiers, and avalanche forecasters alike.  Many slopes are stable and lull us into a false sense of security, but the facets and other persistent weak layers buried deep in the snowpack occasionally rear their ugly heads, causing MODERATE danger to linger…and linger. 

Remember that advisories are merely advice; you and your partners should use them as a valuable piece of the avalanche puzzle but only you can decide exactly when and where to play in the mountains.

Scotty Savage has spent thousands of days in the field evaluating avalanche conditions while at work and at play.  Currently a Friends of the GNFAC avalanche educator, Scotty plans on spending less time with knee surgeons and more time on skis in the coming months.        

Inquiring Minds Want To Know

By Doug Chabot

Published in the February 17, 2012 magazine Carve.

By mid-January over 2,400 people attended one of our 35 avalanche classes.  Grade school and graduate students, skiers and snowmobilers, search and rescue groups, ski patrols and businesses attended classes, all there for the same thing—to learn about avalanches.  Regardless of the user group, during the Q&A sessions people asked similar questions.  Here’s an attempt to answer the most common ones.

What do I need to know about beacons before buying one?

All avalanche transceivers work on the same frequency of 457 kHz.  All brands are compatible with each other and digital models work with analogs.  The newer digital models have multiple antennas and are intuitive to use.  Practice is still essential for a speedy rescue, but they are light years better than older models.  For batteries, use alkaline only.  Lithium batteries do not discharge at an even pace and the beacon’s battery meter will give erroneously high readings.  They stay powerful until the bitter end, and then die quickly leaving a rescuer with a worthless piece of electronics.  Rechargeable batteries should be avoided at all costs since they do not hold a charge for very long.  Get a good, new beacon and don’t skimp on batteries.  Once my beacon falls below 80% capacity I replace the batteries.

If a slope has previously avalanched, is it safe with new snow on it?

The simple answer is no. Weak layers are not easily destroyed, especially thick ones, and new snow would only rebury this layer creating instability and future avalanches.  This winter our New Year’s weekend avalanche cycle broke on a 1-2 foot thick layer of weak snow called depth hoar.  Since this layer is thick, all of it did not get swept away.  New snow might avalanche again, and again on this layer.  Many years ago another forecaster and I were in the middle of an avalanche cycle at Cooke City. We investigated a few slides and that night it stormed.  In the morning I skied onto a 30-degree slope that appeared unscathed, but I found the freshly buried crown indicating it avalanched yesterday.  I called my partner over since I figured the slope was safe.  As we dug our pit the entire slope cracked and moved a few inches right at the pit wall.  The weak layer was still there, as unstable as ever, and we were lucky the slope didn’t avalanche again.

Is a slope more stable after it collapses or “whumps”?

The whumphs we hear and feel are buried weak layers collapsing in the snowpack.  When they collapse but don’t avalanche it doesn’t mean they are stable.  Slopes have avalanched after collapses.  Two years ago a Montana ski patroller got a large slope to crack 1.5 inches wide with explosives, but it did not avalanche.  Another shot was placed in the crack and moments later the entire slope released.  Treat slopes that have fractured or collapsed with caution. They may not be immediately safe and should not be trusted.

Isn’t avalanche terrain big and obvious?

We typically think of avalanche terrain as big open bowls or long chutes.  We disregard the smaller hills on the ski in, yet any open, snow covered slope over 30-degrees steepness can slide.  And it doesn’t take much snow to bury or kill a person.  Recent data shows that almost 50% of all avalanche accidents happen in slides that ran less than 500 vertical feet.  Sure, your partner will find you quickly in a small avalanche, but don’t ever forget that even though 90% of folks dug up in 15 minutes survive, 10% don’t.  If I had a 1 in 10 chance of winning the lottery I’d play it every day.  But dying?  I think I’ll pass.

Can I ski out of an avalanche by aiming towards the edges of it?

If the slide is small and you’re at the top when it breaks and you’re an expert and your bindings don’t release and your skis are pointed towards the side---maybe, just maybe.  But maybe isn’t definitely.  An avalanche can accelerate to well over 80 m.p.h. in seconds, too fast to outrun.  If caught in an avalanche, something has gone terribly wrong.  Even with a perfect plan, expert ability and a cool head, once caught, unmanageable outside forces strongly influence life or death.

Don’t ski tracks on a slope mean it’s safe?

Ski tracks on a slope give a false sense of security.  Many people have been caught and killed in avalanches on heavily tracked slopes.  In order to avalanche, a slope must be steeper than 30 degrees, have a slab of snow over a weak layer and, finally, a trigger.  If a person cuts an unstable spot on the slope it can initiate fractures which will propagate outward avalanching all previous tracks.   A uniform weak layer buried deep in the snowpack can fail and create a slide, no matter how chopped up the slab above it is.

The Human Factor - The Avalanche Wild Card

The Human Factor - The Avalanche Wildcard

By: Eric Knoff

Gallatin National Forest Avalanche Center

During the New Year’s weekend of 2011/2012, avalanches killed 3 people.  Two of these fatalities occurred in the mountains near Cooke City and the third in the Flint Range near Phillipsburg, Montana.  This is more avalanche  fatalities than the entire state of Montana tallied all of last season, and this season is still young.  All three victims were Montana residents and were considered skilled at their respective sports. 

Why do experienced skiers and riders get caught and sometimes die in avalanches?

Because  we are all human and make  mistakes.  But if the consequences of a mistake include death, shouldn’t it be easy to make the right decision?

Research suggests that the 'Human Factor' creates conditions for most avalanche accidents to occur when people with at least basic avalanche awareness are involved.  Factors including  familiarity of terrain, riding with a more experienced partner and social acceptance (peer pressure) play a significant if not dominant role in avalanche accidents.  If snowpack instability was the sole factor driving our decision making process, avoiding avalanche hazard would be simple.  If there is unstable snow then stay out of the backcountry, but  the 'Human Factor' is a diverse and complex component of risk assessment and does not follow a simple, quantifiable formula.  

 A research study conducted by Ian McCammon reveals that familiarity of terrain has the strongest effect on avalanche trained parties.  McCammon discovered that groups with advanced avalanche knowledge exposed themselves to nearly twice the hazard level of less educated groups when riding in familiar terrain,  about the same level of hazard as parties with no avalanche training at all.   That is, familiarity with a certain backcountry area can lead us to take chances we would not take in unfamiliar territory. 

Another powerful component of the 'Human Factor' is the tendency of less experienced riders to follow  a leader.  Often, a specific member of a group is relied upon to make critical decisions based on their perceived experience.  Research shows that larger groups - 3 to 10 people - with a 'perceived leader'  make significantly riskier decisions than the same sized groups without a leader.  According to McCammon, following a leader simplifies the task of complex decision making.  This type of thinking - or lack thereof - can at times send the party astray.  Groups who follow an individual with less backcountry experience are more likely to be involved with an avalanche incident than groups with an experienced backcountry leader.

Possibly the most powerful component of the 'Human Factor' is the desire to be noticed and accepted,  more commonly known as ego.  In more challenging terrain,  some humans tend to fall into a competitive mentality and pushing the bar becomes more important than individual or group safety.  This sort of non-thinking  skews the decision making process of even the most skilled backcountry rider.

Avalanche accidents  seldom occur because of a lack of information regarding weather, snowpack and terrain.  The problem is how  backcountry enthusiasts process this information.  In order to prevent avalanche accidents and save lives, riders must gain a better understanding of the dynamics of the 'Human Factor' and how it directly contributes to avalanches.   Studies continue to indicate that education and experience are the leading combatants against decision making errors.   Improving situational awareness through education and training  helps identify the dynamics of the 'Human Factor' and ultimately improves  the safety of people in avalanche terrain.

Clear Skies Does Not Always Equal Clear Sailing
A Look At The Formation Of Persistent Weak Layers

By: Eric Knoff
Published in the January issue of MSA News

The snowpack is a record of weather events that take place during the winter.  Heavy snows, wind, even
long dry spells, help to create unique layers in the snowpack. The order in which these weather events
occur determines both the structure and stability of the pack.
The layers that tend to cause the most avalanche problems throughout the winter generally form
between storms.  Known as persistent weak layers, there are three main types that form in
southwestern Montana - depth hoar, surface hoar and near surface facets.  Each of these is capable of
existing in the snowpack for long periods of time and can produce avalanches weeks - or even months -
after a storm.

A weak layer is one of the four ingredients required to create an avalanche- the other factors being
slope angle capable of sliding, a slab of snow and a trigger.  It may seem counter-intuitive, but weak
layers are often created during dry spells - it is important to pay attention to changing structure in the
snowpack, even when there is no new snow.

The main process that drives the formation of persistent weak layers is strong temperature gradients.
Gradients are essentially the difference in temperature over a distance - in this case the difference in
temperature between the ground which is at a constant 32 F during the winter and the air temperature
which varies daily.  Temperature gradients are responsible for the formation of facets in the buried
layers of the snowpack.

Shallow snowpacks often fall victim to large temperature gradients - sparking the formation of weak,
sugary snow near the ground known as depth hoar.  Depth hoar forms when there has been a storm or
two, providing a shallow snowpack,that is exposed to a cold and clear weather pattern.   If a cold clear
pattern persists, faceted grains will form and can become cup shaped, reaching 4-10 mm in size.  These
grains have a hard time sticking together due to their angled structure and large crystal size.  Typically,
the larger the grain size the more persistent the instability.  Depth hoar layers easily can become
preserved deep in the snowpack and create instability for weeks or even months.

As the snowpack becomes deeper throughout the season, temperature fluctuations mostly impact only
the top 15-20 cm of the snow surface.  The longer the surface is exposed to large day and night
temperature swings, the weaker the snow surface will become.  This process is called diurnal
recrystalization and creates small angular grains known as near-surface facets. These faceted layers can
become buried by subsequent storms and linger for extended periods of time.  In southwest Montana,
nearly 60% of all human triggered slides occur on near-surface facet layers (Birkeland, 1996).A less common but equally dangerous persistent weak layer is surface hoar.

This layer is the dew of winter, featuring large feathery crystals that form during cold, clear and calm nights.   Due to the fragile nature of surface hoar crystals, they are easily destroyed by direct sun or wind.  But patchy surface hoar can survive weather events.  Once buried, sporadic distribution can make this layer both
unpredictable and hazardous.  Buried layers of surface hoar are renowned for fracturing far and wide
and can create avalanches that are capable of propagating into low-angle terrain.

The next time Montana’s under a spell of high pressure, look closely at the snow surface.   Future weak
layers are likely forming.