Thursday, 7 February 2013
Landmines and Avalanches
A lad on uk.climbing doesn’t quite understand the circles in the avalanche forecast and how to apply them to the avalanche risk so it made me ponder. My take is to think of them as featherweight landmines blown by the wind, lurking in the eddies, the colour of them is the sensitivity of the pressure plate to you the trigger. If there are enough of them the explosion will propagate setting of others, or if the surrounding slope is weak enough then it will slide with it.
When a slice or aspect of the SAIS “wagon wheel” is all orange or red then you would avoid that slope –wouldn’t you? If you think there are mines in there, you must choose your path carefully or play Russian Roulette with God. It’s not less dangerous just because its moderate just less obvious and it's just a question of load/pressure to reach the trigger point. If the visibility is bad, or you are crap at navigating and/or make a poor route choice if tired then BOOM!
Reports such as the above showing circles or areas of "considerable" risk within a moderate NW to E is the sort of thing that it's easy to become complacment about as its a common feature of the Scottish winter. You might very obviously if you have any sense stay well clear of the West to South East apsects but wander into a high risk situation on descent on the NW to East aspects. The majority of avalanche incidents in Europe occur in these moderate to considerable forecast days as they occur most frequently 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.