Wednesday, 16 November 2016

Know Before You Go at Glencoe

Winter is a great time to be in Lochaber. We are blessed with two ski areas both of which offer vastly different views and an experience both on and away from marked trails. Mountaineers also flock to the area as Scottish winter mountaineering is legendary requiring a toughness and resilience in often adverse weather, but amply rewarded by unique rime and ice formation or snow ice if you persevere.

If you’re a skier, then its “freshies” which are the holy grail. These first few tracks down a pristine slope with six inches or more of new snow are what it’s all about. Scottish powder snow is less Champagne and a bit more Sauternes but equally nice to float the wide skis down in big carving arcs of sweetness.

Whether mountaineer or skier, when the fresh snow comes its usually got wind behind it and somewhere on a lee slope the build-up of snow will be deep.  Avalanches tend to occur on slopes of an angle of about 30 to 50 degrees where this snow lays, and are most often triggered by the additional load of the victims. Sadly, many Scottish Corries have streams and gulches/gullies at the bottom and these trap the victim and so bury them deeply.

Folk need to “Know Before You Go”  

Get the gear and carry an avalanche beacon so you can be located, and which will also search for your friends. Three essentials including the Beacon also includes: Carrying a snow probe so a victim can be precisely located, and having a good alu shovel so you can dig someone out. Also, consider adding two Recco reflectors so your more searchable. Mountaineers shun the three essentials but Recco reflectors might at least give them a chance
Get some training on how to understand how avalanches occur, common cognitive mistakes and thinking traps that make us ignore obvious danger signs, and conditions. This will include how to interpret the weather and avalanche forecast and some basic understanding of snow crystals and how strong and weak layers’ form within a snow pack, also on how to search and dig out a victim and look after them. Glencoe Mountain has a state of the art training park for folks to practice with their avalanche beacons and digging and the ski patrol are always happy to give advice. I run some avalanche training up at Glencoe so please contact me via my web site for more information.

Get the forecast. Never go out without reviewing the weather for the day ahead and always look at the Scottish avalanche service forecast (SAIS) and take heed of the risk level and the forecasters observations. The bulk of avalanche incidents do not happen when the risk level is high but when its lower as folk assume it’s safe. Always bear in mind there is never no risk, just a lower risk.

Get the big picture and become a good observer of the precipitation, wind loading and conditions around you and underfoot, and add that to the information from the avalanche forecast and be prepared to change your objectives. The avalanche forecast is an area forecast and a Corrie or mountain may well have very different avalanche risk from local wind and weather effects. Look for “Red Flag" signs of recent avalanches, cracking or collapsing snow, new snow and drifting snow, also rapid thaw conditions. If these are observed, then change your route to a safer one or cancel your day and retreat.

Stay out of harm’s way. With the big picture, you will be looking around you and adjusting your risk assessment constantly. If a mountaineer look above you as someone may trigger a cornice collapse which takes you out. You may commit yourself into enclosed terrain where, if an avalanche spontaneously triggers you have nowhere to run. A ski tourer might skin up into similar terrain and be trapped. Or, if dropping into a Corrie you could be taken into a terrain trap as mentioned before. If its misty or a whiteout you have no way of knowing who or what is below you and if it does avalanche your friends cannot see you from above and may be unaware.

Terrain Trap - No where to go and buried deeply!

Important Considerations Before the Point of No Return, or Dropping In

Angle. Most avalanches are triggered on slopes roughly between 30 and 50 degrees. Below 30 degrees’ victim triggered slab avalanches are less common and above this angle slopes purge more frequently. The "Sweet Spot" where most avalanches are triggered is about 40 ish degrees with over 90% of victim triggered slides occurring in a 7-degree range bracketing that sweet spot. You can conclude from this that angle is an important part of slope assessment and subtle changes of angle on a given slope can have major consequences, therefore route choice and awareness of slope angle is important. Modern phone apps make judging the angle much easier. Rule of thumb for me personally is that as the avalanche forecast risk for a given altitude and aspect goes up - then the angle and altitude of what you ski comes down.

Anchors. What is the snowpack connected to? Have you been following the weather and avalanche forecast? Are there weak layers within the snowpack? Tree's and rocks can hold a slope as your friend or can be weak spots as your enemy where sun, heat, graupel or hoar frost has gathered. Subtle angle changes create trigger points at these places. Tree's are also natures cheese grater if you get taken into them. Ask yourself what the slope you are on is linked into from the underlying snowpack. Unstable snowpacks can often propagate a collapse into nearby slopes and draw an avalanche into lower angled terrain.

Aspect. Which compass direction does the slope you want to ski or travel face. Like angle, subtle changes in aspect can take you from a safe slope onto a loaded one. Carry a compass and learn about "slope aspect" i.e. which way it faces, as both a navigation and safe travel tool.  The SAIS forecast gives you the necessary hazard warning for compass direction but you need to apply it on the ground accurately. Some phone apps can help with this and even give you the area forecast 

Altitude. You can see by looking at the SAIS forecast that the hazard risk is most often greater with altitude, even in Scotland. The rate of snow deposition is higher with height, and the wind is also stronger increasing side loading of slopes. On dodgy days stay lower as well as skiing lower angled slopes

Complexity. As mentioned above. Be aware of subtle changes in angle and aspect and that localised instabilities are hidden and like a landmine can link one triggered mine to a chain reaction and a small slide gathering surrounding instabilities into a major avalanche event. Learn to read mapping for subtleties of terrain features and how snow may be affected, and think safety by pre-imagining what could go wrong. If it's a complex route, then it’s often unsafe as there are too many unknowns. Learn to know what you don't know!

Commitment. Always have a plan "B" so that if conditions change or are not what you expected you have another safer option. Commitment to a slope can mean no bail out options, i.e. having nowhere to go.  If you look at the pros on YouTube they choose their line so they can bale out onto a spine and have good runouts, and that's where the next "C" comes into play - consequences.

Consequences. If it’s an amber light's on in your head so you’re in a go/no go process, then add consequence into the thought mix. Are there crags, hollows, stream beds, tree's or any other terrain features that could shred you or trap you if there is an avalanche.

Micro terrain can have macro consequences 
So, as a final thought. Get the gear, get the training, get the forecast, get the big picture, and stay out of harm’s way. 

Davy Gunn
Avalanche Educator and Instructor

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