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  • Llewellyn Murdoch

A climbers approach to avalanche avoidance in the southern alps



A 2020 study of avalanche fatalities in New Zealand showed that 70% of avalanche fatalities since 1999 occurred to climbers and 63%of these occurred during the spring and summer climbing seasons. This is a considerable difference compared to other countries where the same activities take place.


The aim of this blog post is to outline effective strategies to minimise avalanche exposure to climbers in a way that suits how they travel in avalanche terrain.

It can be looked at as a non-exhaustive list of steps that you can take to become more knowledgeable, better trained and more aware of avalanche danger in the mountains.



First things first, get educated! Taking an avalanche course is pretty easy. Time is the main factor; you don’t need to bite off more than you can chew. Start simple and go from there. The industry and the NZ Mountain Safety Council are aware that courses currently do not cater to climbers as much as skiers and are working to rectify this. Despite this, the courses are still very worthwhile and equip you with important skills on avoiding and mitigating avalanche danger and on rescue techniques.



Practice the skills you learn

The foothills of New Zealand (anywhere outside of the Southern Alps) are generally safer places to practice to solidify your skill sets before heading into the big mountains. This is especially true during the winter when days are short and conditions are generally more difficult in the big mountains.



Stay interested and informed.

Tracking storms and avalanche cycles is something that professionals do to stay aware of what’s happening in the snowpack. Being engaged in your local terrain, or the terrain you have trips planned for will give you a better understanding of what is happening in the snowpack as well as travel and climbing conditions.


This is a simple but time-consuming task. The idea is to note down significant weather events and then match those with the snowpack information you can gain from observations, the New Zealand Avalanche Advisory (NZAA), or going out and gathering information yourself.


Once you feel well trained and knowledgeable enough to head into the Southern Alps, having a measured approach is the best way to stay on top of conditions, make smart decisions, come home safe at the end of the trip, and hopefully climb a good route while you are at it.


Below is an example of how I operate when traveling into the mountains to climb, say one of the 3000m classics in NZ. Starting from walking in from the trail head, climbing the peak and returning back safely to my car.



PRE-TRIP:

Before choosing an objective you have some work to do! Remember conditions should dictate your objective, not the other way round.


Read the public New Zealand Avalanche Advisory (NZAA) for the area you want to travel in.

This information comes from a trusted source who has taken the time to investigate what is happening in the snowpack and has a good idea of any recent avalanche activity. More detailed information like storm or layer tracking may not make it into the forecast, but the forecasters have the information and share the relevant parts. If you have been doing your own storm or layer tracking then this can be a confirmation of what you have been guessing would occur. It can also provide insights into any issues you may have missed.



Gather information and observations from other sources. This may be people who have been climbing or skiing in the area, but also could come from avalanche observations, snowpack information, or weather observations. This is what we call Class 1, 2 and 3 data, the three most important factors indicating avalanche danger. Getting quality first-hand information is a huge help to your decision-making process.


Gather detailed forecasts for the weather window including the following for each day:

• General statement for the day Eg:

• Fine with increasing clouds, snow showers from afternoon

• Forecast precipitation Eg: 25mm

• Forecast wind Eg: North westerly 30km/h rising to 80km/h

• Forecasted free air freezing level Eg: 2000m



In a pocket notebook make a trip plan for each day. \Write down the NZAA forecast for the applicable days.

During a longer trip leave this area blank for the days after the first or second day. You can then rewrite or change the avalanche forecast as you gain more information.


Write down the weather forecast for each day. Leave enough space in this area to adjust the forecast if you get an update while in the mountains from the mountain hut radio or via Satellite communications. Many alpine huts will also broadcast the avalanche forecast on the daily sched via radio as well.


What you have done here is captured all the information you have from external sources that influences avalanche hazard during your trip. I also like to write down any pertinent additional hazards that will contribute to my decision making; crevasse fall hazard, large cornices expected on the route, etc.


Once you have this information you can then complete a plan for each day of the trip.


It is important to write down the avalanche forecast and the weather forecast and discuss this with your climbing partner/s prior to completing the trip plan. This will highlight which aspects, elevations, and features you need to avoid due to avalanche danger as well as determine what equipment you need to take with you.

Deciding on an objective prior to reviewing the avalanche and weather forecasts leads to forced trip plans that may be unsafe.



Be patient.

Giving the snow time to settle after a storm significantly reduces your probability of being caught in an avalanche. The weather in New Zealand can be frustrating and make you feel like you need to do big objectives in short weather windows. You don’t. Give the mountains a minimum of 24 hours after significant snowfall or wind loading and make sure you have some margin on the weather window to get off the mountain before another storm hits.



All trip plans should have options.

This may reflect your overall objective, for example:

We want to climb the east face of mountain A but if we observe more wind transport or avalanche activity than we expected we will climb the west ridge of Mountain B.

or options on your chosen objective ie:

If we arrive at the snowslope later in the day than planned, we will traverse to the ridge and wait for the sun to come off the slope.


If safe alternative options like this are not available, for example because there is an incoming storm or there are no safe places on the mountain, you will need to be conservative. An example is turning around early if you are going slower than expected. It doesn’t take a genius to know that climbing into situations that have no safe alternative or bailout options doesn’t lend itself to a long life.


The notebook also has space on each day's page for any avalanche, snowpack and/or weather observations you make during your day out.

You can review these in the evening and make adjustments to your forecast for the following day.


It's important to review the forecasts and agree upon a plan with your climbing partner It is surprising how much of this topic people leave unsaid before leaving the carpark.




WALK IN:

Starting at or close to sea level and walking into alpine terrain, where avalanche hazards exist, is part of every classic New Zealand alpine climbing trip. Some approaches take a single day and others multiple, but the one thing you have plenty of in any case is time.


Time to make observations.

Targeted observations of the mountain terrain that you are moving into should be a high priority of any walk in.This is your first look at the mountains and your first chance to see conditions for yourself.

The goal of targeted observations is to gather real world evidence that supports or challenges your weather and avalanche forecast.

These observations could make you more or less confident, change your travel plans, or even lead to a turn-around but the important thing is that you start to make use of all available information. Remember it is important to always share these observations with your climbing partner/s and discuss the implications.


Observations could include:

• Natural avalanches; recent or currently occurring

• Can you see crown walls?

• Recent sizeable debris on lower angled slopes or at valley floor

• Slab avalanches or Loose snow avalanches are most likely directly after a storm

• If there is not widespread avalanching, look for slopes directly below ridge crest or under active ice falls. These areas have large natural triggers which will increase likelihood of avalanching.

• Signs indicative of an unstable snowpack

• Shooting cracks on the surface while skiing or walking

• Slope collapses or “Whumping”

• Density inversions within new snow. (Hard snow over less hard snow)

• Current weather conditions;

• Current precipitation and rate

• New snow

• Wind direction and speed

• Blowing snow

• Temperature


There is a lot to unpack if you are traveling in avalanche terrain and are observing natural avalanches. The one thing to remember is that if you are witnessing avalanches occurring naturally then the likelihood of human triggered avalanches is significantly increased.

Extreme caution should be applied if you decide to move forward.




Slab avalanches/loose snow avalanches

As stated above, slab avalanches or loose snow avalanches are most likely directly after a storm and when walking into the big mountains you will likely see some recent avalanche activity.

Loose wet avalanching is extremely common in spring during the first 24hrs of fine weather post storm. The rising freezing level and direct solar input causes new snow to lose cohesion. When this starts as a small point release, it can entrain large amounts of snow. Think about the size of the slope, big mountain sides, lots of snow to build into a large avalanche

Wind slab avalanches are also common in spring as wind, especially the common SW clearance, transports new snow onto lee slopes and forms stiff slabs above a less hard layer of new snow. These avalanches are usually dangerous for 12-36 hours after formation, sometimes longer in cold periods. These avalanches are often triggered by intense wind loading, cornice or icefall in the big mountains and can run down to valley floor in steep confined areas.


With these factors forming avalanches, it is clear that avalanche activity is likely post storm.

Some mountain approaches are much more hazardous than others. If you are making observations of rapidly changing conditions or worse avalanche hazard than expected, then you should re-evaluate your plan with your partner/s.


Consider the following:

• Do the avalanches you are observing have the ability to run to or across valley floor?

• Could you conceivably walk into that run out?

• During your approach that day do you have crevassed areas that may force you into the run out?

• As you get high on the glacier that day do you need to cross aspects that have similar characteristics to the slopes where you are seeing avalanche activity?

• If avalanche activity is widespread do you have the knowledge and skill set to avoid it?

• Is the weather and avalanche danger improving or deteriorating?

• How is the visibility? Will it hinder safe travel practices and further observations?


Ideally you have already considered these questions in your trip planning and have chosen an objective with an appropriate approach given the expected avalanche hazard.

If the conditions are worse than anticipated, then you may need to change your travel plans to suit the real world conditions.

If you have no options to maintain safe margins this could mean turning around, which is a frustrating thing to do, but a much better alternative than wandering all day into dangerous avalanche terrain and then deciding you have to turn around much later in the process. Of course it could get even worse if you end up involved in an avalanche.


At the end of a day’s approach, when you reach camp or an alpine hut, remember to write down observations, update the weather forecast and reevaluate your avalanche forecast for the following day. This should trigger robust conversation and either a confirmation of your plan or a re-evaluation for the following day.


CLIMBING DAY:

The above considerations and strategies should be applied to any climbing day.

Further to that, it is important to note that there are a few drastic changes that will influence avalanche hazards and exposure during the climbing days in NZ.


Average hut sites sit around 1800-2300m, which means climbers commonly gain around 1500m of elevation during a climbing day, sometimes more. This is a significant change in elevation, which can mean changes in avalanches type and significant increases in hazard.



Terrain steepness and exposure will change from relatively flat valley and glacier walking with overhead hazards, to climbers moving on, through, and underneath, significant avalanche terrain. Due to the steepness of the terrain, the likelihood of human triggering avalanches increases. It is also important to note that even very small avalanches are a big danger to climbers. Being swept off your feet by a small avalanche in steep climbing terrain could easily kill a climber on most “easy” NZ alpine routes.

“Alpine starts” and long days mean that travel in the dark is a common occurrence, hindering observations as well as decision making. Another reason to make good quality observations the day before and have a robust discussion around decision making prior to the climbing day.

Descending onto unfamiliar slopes after summiting during a long tiring day is another red flag.


Most peaks in the Southern Alps sit on or directly adjacent to the main divide which is a major catching feature for any wind or storm event. Significant avalanche formation can occur during even summer storms at the higher elevations. Permanent, hard summer snow or glacier ice can form a bed surface for wind slab any time of the year and loose snow avalanches can run year-round on the same surfaces.

Cornices are a near permanent risk on the main divide and a risk that is difficult to predict.

Strategies to minimise the above risk and/or gain some information:

• Continue making observations as noted above and make time to share and discuss these with your climbing partners.

• Keep an eye out for wind transported snow year round, this could form a slab in the lee

• Feel the snow surface under you, stop and investigate any changes

• Hand shears and pole probing will give you information about any near surface instabilities

• Stop and investigate when you change aspects, especially when descending after climbing on the southern side of the mountain

• Use of the rope can be helpful on small avalanche slopes, to protect from small avalanches but you need good anchors and protection that is out of the snow. This is not a safe strategy on big slopes.

• Cautious approach to cornices and the use of pitching can minimise but not eliminate this risk to the climbing team.

• Be wary of steep solar aspects in the afternoon. If your crampons are balling up then the chances of a loose wet avalanche may be increased

• Wait until solar aspects cool off at night before descending

• Avoid crossing avalanche terrain at night if you are concerned about wind slab avalanches. You cannot judge if the slope is loaded and you won't be able to see your partner if they do trigger an avalanche.



WALK OUT:

Many of the same skill sets should apply. The more days you are in the mountains, the more understanding you should have of the conditions and what aspects and elevations you are happy to travel in. Keep up the observations and forecasting in your notebook, and keep up the conversations with your climbing partner.


As you lose elevation and move away from the steeper terrain then the avalanche risk will likely decrease and in most cases you go back to only needing to be concerned about overhead hazard. It is easy for climbers to drop their guard on the descent or walk out and it can be easy to walk into a hazardous area.


Be wary of changing weather as the weather window closes, there could be a new concern building. Again, keep up the observations and this should be avoidable.

If the weather is deteriorating quickly, be observant and think through your options. Is it safe to walk out on the day? Or should you wait out the incoming weather? Don’t let “Get home-itis” sway good judgement.


In spring, warm temperatures at lower elevations may cause an increase in avalanche hazard that you may have been unaware of up at the higher elevations. This is often the case late in the day. Time your walk out accordingly if there is snow at lower elevations in steep terrain.



AT HOME

A few things that are good to do once you get out:


• Submit public observations of what you observed on the New Zealand Avalanche Advisory website at avalanche.net.nz

• Discuss your decisions and any learnings with your climbing partner

• Adjust notebook format to work for you

• Adjust packing lists



This is an overview of how to operate safely in the mountains in regards to avalanche hazard. More education and training is recommended whenever you have the time and energy to soak it up.


If you are looking for more information on trip planning, visit the NZAA and read their trip planning resources.




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