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The Scottish Avalanche Information Service (SAIS) has reported rapidly changing conditions in the high Scottish mountains and avalanches occurring in shorter spaces of time. Fluctuating weather caused by significant storms brings about short periods of ‘proper winter’. These are often followed by rising temperatures and subsequent snow loss, and the instability of conditions on higher summits means that avalanche forecasts can change quickly.
The SAIS provides daily avalanche risk forecasts via their website and app from mid-December to mid-April, with the website being the main source of dissemination of snow and avalanche reports for the area. Forecasters use internationally recognised criteria to assess the avalanche risk in areas of Scotland including Glen Coe, Lochaber, the Cairngorms, Creag Meagaidh and Torridon, covering some of the UK’s highest mountains such as Ben Nevis and Ben Macdui, and popular summits such as Cairn Gorm, Liathach and Buachaille Etive Mòr. Forecasters carry out field observations by digging pits into areas of snow cover to identify layers of weakness that could cause an avalanche.
the snow line that was quite low in the past, is now much higher so we are not seeing those cues that we generally got to start thinking about any avalanche hazard
Rapid changes in conditions high in Scotland’s mountains have been apparent over the past few weeks, with days of heavy snowfall followed by higher temperatures and significant snow loss. Met Office data showed the January and February temperature on the summit of Cairn Gorm, had on average been two degrees higher over the last 30 years than it had been during the previous 30.
Diggins said that it was likely that receding snow lines on high Scottish mountains was a sign of climate change, and that this could also inhibit people’s ability to identify early signs of potential avalanche risk.
‘What we are seeing generally speaking, is the snow line that was quite low in the past, is now much higher so we are not seeing those cues that we generally got to start thinking about any avalanche hazard.’
Dr Mike Spencer who works on financial and climate challenges with the Smart Data Foundry at the University of Edinburgh, said that recent research within the Snow Survey of Great Britain suggested Scottish winters are changing. The dataset collected from the 1940s until the mid 2000s found that the number of days with snow lying had decreased since the 1990s. Dr Spencer told the BBC:
‘Since the snow survey ended there have been a handful of very snowy winters, but many winters the snow cover has been less consistent than in the past.
‘This changeable weather is likely to mean periods of intense precipitation alternating with drought conditions – something we’re already seeing more frequently. In the mountains rising temperatures are likely to mean less days of precipitation falling as snow, and when it does the duration it lies for will be reduced.’
He said climate models suggested Scotland was still likely to see winters with very heavy snowfall, but that these were expected to become less frequent due to warming average temperatures.