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 www.crankitupgear.com 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.
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| 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.
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Micro terrain can have macro
consequences
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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.
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Davy Gunn
Avalanche Educator and Instructor
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