Multi-year snow.

21st January 2017

It was a lovely clear day in Lochaber. The snowpack remains relatively limited in extent, and what does exist is very hard and icy. The avalanches hazard remains low.

The South side of Coire an Lochan.

The North side of Coire an Lochan.

Carn Mor Dearg and Ben Nevis.

The North-East Face of Aonach Beag the site of one of the more permeant patches of snow in Scotland, it has only melted once in the past ten years (in the Autumn of 2011). What is interested is the low altitude at which it sits, around 920 meters. This is about 200 meters lower than the snow patches that regularly survive throughout elsewhere in the country (the two other main sites are on Ben Nevis and Braeriach).

The reason is survives so well at this low an altitude is due to a number of factors. The patch itself sits below a depression in the large face above which funnels spindrift, stuffs and avalanches down onto it, so the snow builds up to a great depth. Some old dirty avalanche debris could be seen sitting on top of the snow patch (see pictures below). Some of the other reasons it survives so well are that it sits on soil rather than scree or rock (which makes it difficult for the air/water to get underneath to melt it out from below), and that due to it’t location it is sheltered from the worst of the weather, and gets very little direct sunlight.

I had a look at it when the first snows fell back in late October after which it was soon buried by November snowfall. At that time it was 50m by 25m by 3m deep. Today the multi-year snow was buried by this years snow fall, but not very deeply. I suspect that unless this winter/spring bucks up it’s idea in terms of snowfall, Aonach Beag snow patch won’t be making it through to next winter.

Aoanch Beag today (21/1/2017). The location of the multiyear snow is around where the brown avalanche debris at the bottom of the face is. 

A picture taken from roughly the same point in early November when the first snows of this winter arrived. I have highlighted the multiyear snow in red. The patch was about 50m by 25m. Will any multiyear snow make it to next winter? 



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