Friday 27 March 2020

Plenty of snow for 2020.

For the past few years I have written a post about the amount of snow on the Scottish hills, usually some time during April. Although not quite there yet, I thought given current events and perhaps the lack of opportunity to return to the hills for a while, I thought it would be a good time to write a piece about this winter's snow cover.

However, before discussing this season, I thought I would have a look back at what I wrote last year, which can be found here, and compare with what actually occurred. I had said  "I think it would take a combination of an unusually cold snowy spring followed by a cool dry summer for any snowpatches to survive through to next winter. I don't think it is likely they will survive this year, but am hoping to be proved wrong about that." Well, I was proved wrong, but only just, as one tiny remnant of the the Sphinx patch over in the Cairngorms did survive to be buried by this winter snow fall.

Ben Nevis on the 7th of February 2020. Not looking particularly snowy. 
I am glad to say that this year the things are looking a lot more positive than they did this time last year. Due being in Antarctica working on the Thwaites project this year (see my previous blog posts), I missed the beginning of the winter. However, it was generally mild, stormy and wet, and I don't seem to missed much in terms of winter conditions during December and January.

I finally made it back to the UK on the 9th of February, just in time for my train from London to the Highlands to to be cancelled due to Storm Ciara. Snow cover at that time was pretty poor for the beginning of February, and it was looking like could be another lean year for the snow patches. However, Storm Ciara, Storm Dennis and the following few weeks of unsettled weather dumped a lot of precipitation on the West of Scotland. The Met Office West of Scotland rainfall total for the month of February was 339.8mm, which is 237% of the 1980-2010 average. Interesting despite rainfall being over double average the, sunshine was not too far of average with 59.4 hours; 92% of the mean value.
Coire an Lochan on the 20th of March 2020. Loads of snow!
 Although not particularly cold, it was cold enough for the majority of this precipitation to fall as snow on the hills. With the winds being consistently between the South and the West, the North and East facing coires and hollows where the long lying snowpatches lie really filled in well. Weather wise March started off on a similar note before settling down around the middle of the month. By then there was a great deal of snow on the hills.

In the past I have posted a series of images of the South side of Coire Lochan of Aonach Mor, see the link near the beginning of this post. These pictures are generally taken in April rather than March. However, with but with the long range forecast being relatively cool and dry the snow quantity is unlikely to be significantly different in early April that that shown in the picture above.

To summarise the results of a comparison with other years, there is more snow now in Coire an Lochan any other year since at least 2005 with the exception of 2013/14. Below is a photo from March 2014, what do you think? I don't think there is much in it in terms on snow quantity.
A picture from the March 2014. I would say generally pretty similar in terms of snow quantity to March 2020.  
Over on nearby Ben Nevis most years a patch survives in Observatory Gully, the large bowl/gully in the centre of the pictures below. The locations of this patch is about two thirds the way up the gully, just below where it narrows significantly. Comparing the two pictures below, one from the 22nd of March 2020 and the other from March 2014, it looks like this area of Ben Nevis had a more snow during 2014. However, there are other areas of Ben Nevis where the amount on snow looks very similar.
Ben Nevis on the 22nd of March. A lot of snow, although not quite as much as 2014.  I would say that the Observatory Gully patch is very likely to survive the summer, and that the Point Five patch, which is also visible in this shot, has a fair chance.
Ben Nevis in March 2014. Loads of snow in the Lochaber hills that year, which led to a good number of survivals. 
This post has focused of the hills around Lochaber as that is where I am based. I have not been over to the Cairngorms for a while, but the likes of this post by Iain Cameron suggests things are looking pretty snowy over there was well.

So what does this mean in terms of snowpatch survivals? The first of the two main factors that affect this is how much snow there is at the end of the winter, which this year there is a lot of. The second is what happens weather wise through the spring, summer and autumn, and this can also have a significant effect. Although less snow fell in the winter of 2014/15 as compared  to 2013/14,  more snow patches survived during the summer of 2015 than 2014. This was mainly due to a cold and snowy April and May (I went ski touring that year in early June). On the other hand although the winter of 2017/18 was a reasonable one in terms of snow fall, but only one patch survived the long hot summer that followed.

So in summary, it is a promising start,  and that with the the exception of the winter of 2013/14 there is more snow on the Lochaber hills than any time in the past fifteen or so years. I would say it is very likely that snow will survive on Ben Nevis and Aonach Beag this year. As for the fate of more marginal patches like the one found in Coire an Lochan of Aonach Mor, this will depend very much on what the weather does for the next seven months or so.

Coire an Lochan March 2020. Notice how the edge is roughly straight between where I took the picture and the figure as compared to summer where the edge really cuts in. 
Coire an Lochan in summer. The longest lying snow sits on the rocky slab reflecting the sunlight. 
The top of Easy Gully. Notice there is very little sign of the rocky rib on the right.  
The top of Easy Gully in the summer time. The fact that the rocky rib which is so obvious here is almost gone at the moment gives an idea of how much snow there is here at the moment.