|Understanding the SAIS forecast as acting on it could save your life|
This is the most difficult danger level for back country skiers and boarders to assess snow stability. Many of the usual indicators such as cracks, settling, whumpfing and signs of recent avalanche are absent, especially at the lower end of the moderate level. Key indicators are any recent snowfall, and wind deposition. Snow pack tests may help assess stability.
Conditions are generally favorable for travel providing routes are chosen carefully. The snow pack is only moderately bonded on some steep slopes. Areas of danger are usually restricted to certain types of terrain such as bowls and gullies. The altitude, aspect and type of terrain where danger can be expected are usually detailed in the Avalanche Forecast. Remote triggering is unlikely, so you only need to be concerned about the steepness of nearby terrain features.
|29th March 2013 using the older SAIS Graphic for localised considerable hazard|
|Persistent Weak Layer March 2013|
|Large Slab Triggered off persistant weak layer 30th March 2013|
Fatal Avlx x 1 Skier Glencoe
Conditions have become much less favorable. The snow pack is only moderately or poorly bonded over a much larger area of the terrain. Human triggering is possible by a single skier on steep slopes and aspects mentioned in the Avalanche Forecast. Remote triggering of avalanches is possible, so the maximum steepness of the slope above you should be used when deciding if you want to continue.
|New SAIS graphic as stripes for localised "considerable"|
Reports such as the above showing stripes as areas of localised "considerable" risk to North and South within a moderate NW to SW aspect and considerable risk NE to SE. This is the sort of thing that it's easy to become complacent about as its a common feature of the Scottish winter. You might very obviously if you have any sense, stay well clear of the NE to SE aspects but wander into a high risk situation on descent on the N to S aspects. The majority of avalanche incidents in Europe occur in these moderate to considerable forecast days as they occur most frequently in the season and folk become complacent (the familiarity heuristic) and that's why route choice approaching a climb and thinking about descent options prior to leaving and during a trip as wind and weather change should become part of your thinking.
Conditions have become dangerous, most often as a result of significant amounts of new snow, snowfall accompanied by wind or the snow pack becoming isothermal and threatening wet-snow avalanches. The snow pack is poorly bonded over large areas and human triggering is likely on steep slopes (steeper than 30°). Remote triggering is likely and large natural avalanches are to be expected.
Extreme danger levels are rare in Scotland as usually this level is associated with buildings and roads or alpine villages under threat, and usually the result of unusually large amounts of new snow. The snow pack is weakly bonded and unstable. Numerous large avalanches are likely. The weight of the new snow can trigger avalanches on layers buried deep in the snow pack. Natural avalanches can release on slopes of less than 30° Back country touring is not recommended and often impossible. Avoid all avalanche terrain and keep well away from avalanche path run outs.
In psychology "Groupthink" or "Risky Shift" behaviour is well known in groups and most of us will be aware that we have given in to it or even encouraged it. I strongly believe that in avalanche incidents in Scotland this groupthink or risky shift has become the biggest education issue and maybe why we see large group incidents or group events as occured in the Cairngorms when two seperate groups were avalanched last winter. Much has been made of the quick response from folk training in the corrie who helped. And good on them. What I am about to say is not a reflection on these helper folks choices, as I am sure they stayed in safe terrain. The "however" bit though is that just by being there and numbers increase with lots of MRT's training, and groups under instruction, then a larger "Groupthink" takes place. Groups less experienced or not under instruction maybe feel safe, what McCammon labels as Social Facilitation. I would call this a "risky shift". It's often this way in the climbing and skiing honey pots such as the Northern Corries where folk gather. Aonach Mor or ScRL in Glencoe are other places. Even if the waggon wheel of death shows Red on these slope aspects, they are still the places to be seen by the instructor masses who are now at the height of their annual gatherings with paying students. These are the places instructors are familiar with, and therefore where less experienced folk feel safer with an apparent safety in numbers. They maybe went there when they were on a course. Group thinking on a large scale perhaps.
No matter what we do, mountains and people are unpredictable. As a a keen off the piste skier I have to accept that luck is also in there as well, as on good snow days I am first in the que and having gone through the forecasts, stability tests you are only left with how the snow feels under you ski's and gut instincts. Sometimes it's a very subtle thing where in the morning it feels wrong, and by afternoon the snow "feels" safe. I don't know how the feck that would stand up in court! I also know its taken 40 years and I still can't always be sure it all won't go tits up one day. I also know that it pays to voice your opinion when in a group, and make your own choice, not getting swept along by the group and it's most vocal leader. Beware Risky Shift!
If you need an airbag you have fucked up but might survive. If you need your transceiver you have fucked up and probably won't!